Root cause insight into the common BMW blower motor resistor failures

[Bimmer Owner]

Does anyone have insight into what is the root cause (and repair) of the
FSU failure that plagues almost every 1997 to 2003 BMW?
http://www.bimmerfest.com/forums/attachment.php?attachmentid=126060&d=1194115994

Also, does anyone have an idea HOW TO TEST a "repaired" FSU?

The "blower motor resistor", which also goes by FSR (Final Stage Resistor)
or by FSU (Final Stage Unit), is known to fry itself in almost every single
E46 (3-series), E39 (5-series), and E38 (7-series) BMW.
http://www.bimmerfest.com/forums/showthread.php?t=143393

The problem with replacing this ~$100 part is that the new replacement FSU
fries itself just as often as the old one did, so you end up repeatedly
replacing your fried FSU every few years or so.
http://www.bimmerfest.com/forums/showthread.php?t=528566

That's fine for most people (although the DIY is a PITA) - but I ask
this newsgroup whether anyone has any insight into WHAT is actually
breaking - and - why?
http://www.bimmerfest.com/forums/showthread.php?t=309399

Here is the best (admittedly sketchy) wiring diagram we have so far:
http://www1.picturepush.com/photo/a/12467819/img/12467819.png

[jim beam]

that looks like a linear semiconductor controller - an incredibly
antiquated concept for a modern car.

old resistor packs for fans were open wire that sat in the fan's air
stream for cooling. they were generally very reliable if their alloy
wasn't too susceptible to salt.

that unit looks like it still sits in the air stream with that honking
great heat sink and i estimate it's trying to dissipate >100W. that can
only mean it's a linear controller because a modern pwm device can
control high motor currents with very little heat dissipation <10W.

bottom line, a linear controller is always going to get hot and end up
frying itself over time. the only thing you can do is either replace it
with another unit that will ultimately meet the same fate, or undertake
a significant modification.

for the latter, you can try putting an even bigger heat sink on it - but
i doubt there's a lot extra room available. you can also "pwm" it. i
built a similar unit to deal with a linear controller over-heat issue on
my 89 civic.

<http://www.flickr.com/photos/38636024@N00/5068043855>
<http://arduino.cc/en/Tutorial/PWM>

depending on how much time you want to spend on a project like that, pwm
can control superbly and offers benefits like motor speed not being so
susceptible to supply voltage [engine idle voltage drop] etc.

the down side of pwm is that it can generate electrical noise. [poor
stereo installations can be particularly susceptible.] the ideal
solution is to implement pwm with "soft switching", but that's getting
quite advanced.


--
fact check required

[the will]

Blower motor drawing too much amperage taking it out. Change the
blower motor anytime?

[Nate Nagel]

On 03/21/2013 06:55 AM, the will wrote:
> Blower motor drawing too much amperage taking it out. Change the
> blower motor anytime?
>

My thought as well. Have you measured current draw on a new blower
motor and compared it to one that is installed in a car where the FSU
has failed? that would tell you whether there's any merit to this idea
or not.

nate

--
replace "roosters" with "cox" to reply.
http://members.cox.net/njnagel

[jim beam]

On 03/21/2013 03:55 AM, the will wrote:
> Blower motor drawing too much amperage taking it out.

if it were an adequately designed unit, it should tolerate that and worse.

> Change the
> blower motor anytime?

analyze the actual problem - don't just waste money replacing stuff. a
$30 dvm will diagnose this for you, and you should already own one if
you have any ambition to repair any modern vehicle.


--
fact check required

[Scott Dorsey]

Nate Nagel <njn...@roosters.net> wrote:
>On 03/21/2013 06:55 AM, the will wrote:
>> Blower motor drawing too much amperage taking it out. Change the
>> blower motor anytime?
>
>My thought as well. Have you measured current draw on a new blower
>motor and compared it to one that is installed in a car where the FSU
>has failed? that would tell you whether there's any merit to this idea
>or not.

My inclination is to do exactly the same thing I do with the cooling system
issues: blame German engineers who seem to believe that their climate is
typical of the entire world.

I don't see why it is so hard to unpot one of these things and repair them
directly, especially if it's a semiconductor failure. Put a bigger transistor
in there.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[jim beam]

On 03/21/2013 04:52 AM, Nate Nagel wrote:
> On 03/21/2013 06:55 AM, the will wrote:
>> Blower motor drawing too much amperage taking it out. Change the
>> blower motor anytime?
>>
>
> My thought as well. Have you measured current draw on a new blower
> motor and compared it to one that is installed in a car where the FSU
> has failed? that would tell you whether there's any merit to this idea
> or not.

for an "engineer", you're simply not of this planet.


--
fact check required

[Nate Nagel]

Did you have any suggestions for the OP, or did you just show up to
snipe without contributing anything as per usual?

You do know that most electrical/electronic components have a maximum
current rating, yes? And that electric motors tend to draw more current
when the bearings are going or they are otherwise subjected to loads
higher than that for which they were designed? Does any of this sound
remotely familiar to you?

Really, what the will suggested seems to be a logical first step.

[jim beam]

On 03/21/2013 06:47 AM, Scott Dorsey wrote:
> Nate Nagel <njn...@roosters.net> wrote:
>> On 03/21/2013 06:55 AM, the will wrote:
>>> Blower motor drawing too much amperage taking it out. Change the
>>> blower motor anytime?
>>
>> My thought as well. Have you measured current draw on a new blower
>> motor and compared it to one that is installed in a car where the FSU
>> has failed? that would tell you whether there's any merit to this idea
>> or not.
>
> My inclination is to do exactly the same thing I do with the cooling system
> issues: blame German engineers who seem to believe that their climate is
> typical of the entire world.

that's not going to fix it though. and the germans sell a LOT of these
vehciles in the middle east - it's a good deal hotter there than here.
they know exactly what they're doing.

>
> I don't see why it is so hard to unpot one of these things and repair them
> directly, especially if it's a semiconductor failure. Put a bigger transistor
> in there.

unpotting is a nightmare - it will take much less time to build your own
pwm controller. who knows, maybe you can switch the existing unit???!!!


--
fact check required

[jim beam]

On 03/21/2013 06:59 AM, Nate Nagel wrote:
> On 03/21/2013 09:55 AM, jim beam wrote:
>> On 03/21/2013 04:52 AM, Nate Nagel wrote:
>>> On 03/21/2013 06:55 AM, the will wrote:
>>>> Blower motor drawing too much amperage taking it out. Change the
>>>> blower motor anytime?
>>>>
>>>
>>> My thought as well. Have you measured current draw on a new blower
>>> motor and compared it to one that is installed in a car where the FSU
>>> has failed? that would tell you whether there's any merit to this idea
>>> or not.
>>
>> for an "engineer", you're simply not of this planet.
>>
>
> Did you have any suggestions for the OP, or did you just show up to
> snipe without contributing anything as per usual?

<https://groups.google.com/group/rec.autos.tech/msg/1870e822d74b0a5c?dmode=source&output=gplain&noredirect&pli=1>

retard.

>
> You do know that most electrical/electronic components have a maximum
> current rating, yes? And that electric motors tend to draw more current
> when the bearings are going or they are otherwise subjected to loads
> higher than that for which they were designed? Does any of this sound
> remotely familiar to you?

don't lecture me on electronics nate.

>
> Really, what the will suggested seems to be a logical first step.

if you don't know what the FUCK you're doing and don't know how to use a
dvm.


--
fact check required

[Bimmer Owner]

On Thu, 21 Mar 2013 09:47:31 -0400, Scott Dorsey wrote:

> I don't see why it is so hard to unpot one of these things and repair them
> directly, especially if it's a semiconductor failure.
> Put a bigger transistor in there.

Here are pictures from the last half dozen who tried that approach:
http://www2.picturepush.com/photo/a/12470740/img/12470740.jpg
http://www4.picturepush.com/photo/a/12470742/img/12470742.jpg
http://www2.picturepush.com/photo/a/12470745/img/12470745.jpg
http://www4.picturepush.com/photo/a/12470747/img/12470747.jpg
http://www5.picturepush.com/photo/a/12470748/img/12470748.jpg
http://www2.picturepush.com/photo/a/12470750/img/12470750.jpg

Most who try to unpot fail, mainly due to damage caused to the
surface-mount circuit board during the initial mechanical degooping
step.

Those deft few who avoid knocking off the surface-mount components
with the debriding chisel, are left with a badly bruised board,
where some have said they've resoldered solder cracks (see pics).

One problem with "put a bigger xtor" is that nobody on this planet
has produced a decent circuit diagram of the FSU.

Does anyone here have access to an FSU circuit diagram?

[jim beam]

On 03/21/2013 08:04 AM, Bimmer Owner wrote:
> On Thu, 21 Mar 2013 09:47:31 -0400, Scott Dorsey wrote:
>
>> I don't see why it is so hard to unpot one of these things and repair them
>> directly, especially if it's a semiconductor failure.
>> Put a bigger transistor in there.
>
> Here are pictures from the last half dozen who tried that approach:
> http://www2.picturepush.com/photo/a/12470740/img/12470740.jpg
> http://www4.picturepush.com/photo/a/12470742/img/12470742.jpg
> http://www2.picturepush.com/photo/a/12470745/img/12470745.jpg
> http://www4.picturepush.com/photo/a/12470747/img/12470747.jpg
> http://www5.picturepush.com/photo/a/12470748/img/12470748.jpg
> http://www2.picturepush.com/photo/a/12470750/img/12470750.jpg
>
> Most who try to unpot fail, mainly due to damage caused to the
> surface-mount circuit board during the initial mechanical degooping
> step.
>
> Those deft few who avoid knocking off the surface-mount components
> with the debriding chisel, are left with a badly bruised board,
> where some have said they've resoldered solder cracks (see pics).

if people priced their time and ignored the damage in which attempts to
unpot invariably result, it's cheaper to just buy a new one.

>
> One problem with "put a bigger xtor" is that nobody on this planet
> has produced a decent circuit diagram of the FSU.
>
> Does anyone here have access to an FSU circuit diagram?

you don't need it any more than you need the circuit diagram of a chip's
internals - all you need is its function parameters - which you pretty
much already have.

you might be able to pwm the unit itself thus pretty much removing the
heat component thereby prolonging its life [literally] exponentially.


--
fact check required

[Bimmer Owner]

On Thu, 21 Mar 2013 03:55:47 -0700, the will wrote:

> Blower motor drawing too much amperage taking it out.
> Change the blower motor anytime?

This is an interesting approach, given that the vast majority of
bimmer owners do NOT replace the blower motor - they replace the FSU.

While the blower motor replacement procedure is a major PITA, one
'can' test the leads from the FSU harness connector pins #5 and #1
which are power and ground respectively to the blower motor.

Again, we don't have a circuit diagram, but it has been said that
the blower motor takes about 6 amps (variously, depending on the speed)
but it would take a test jig to test that in operation.

To my knowledge, nobody has created that test jig (although I know
of only one attempt, which failed):
http://www.bimmerfest.com/forums/showthread.php?t=678534&highlight=fsu

It's easy enough to test the resistance of the blower motor though,
and those results have come out at about 0.4 to 0.6 ohms.

It would be expensive to change a blower motor on a whim, so, how
would YOU suggest the blower motor be tested in situ?

[Nate Nagel]

On 03/21/2013 10:41 AM, jim beam wrote:
> On 03/21/2013 06:59 AM, Nate Nagel wrote:
>> On 03/21/2013 09:55 AM, jim beam wrote:
>>> On 03/21/2013 04:52 AM, Nate Nagel wrote:
>>>> On 03/21/2013 06:55 AM, the will wrote:
>>>>> Blower motor drawing too much amperage taking it out. Change the
>>>>> blower motor anytime?
>>>>>
>>>>
>>>> My thought as well. Have you measured current draw on a new blower
>>>> motor and compared it to one that is installed in a car where the FSU
>>>> has failed? that would tell you whether there's any merit to this idea
>>>> or not.
>>>
>>> for an "engineer", you're simply not of this planet.
>>>
>>
>> Did you have any suggestions for the OP, or did you just show up to
>> snipe without contributing anything as per usual?
>
> <https://groups.google.com/group/rec.autos.tech/msg/1870e822d74b0a5c?dmode=source&output=gplain&noredirect&pli=1>

link times out?

>
> retard.
>
>
>>
>> You do know that most electrical/electronic components have a maximum
>> current rating, yes? And that electric motors tend to draw more current
>> when the bearings are going or they are otherwise subjected to loads
>> higher than that for which they were designed? Does any of this sound
>> remotely familiar to you?
>
> don't lecture me on electronics nate.

ooh, or what? ITG gonna kick my ass? Sorry, I'm more interested in
helping the OP than your delicate little feelers.

>>
>> Really, what the will suggested seems to be a logical first step.
>
> if you don't know what the FUCK you're doing and don't know how to use a
> dvm.
>

WTF is that supposed to mean?

OP can dissect the thing all he wants but it doesn't do him a damn bit
of good to know *what* has failed unless he knows *why* it failed.

[Scott Dorsey]

Bimmer Owner <donta...@mymail.com> wrote:
>
>It's easy enough to test the resistance of the blower motor though,
>and those results have come out at about 0.4 to 0.6 ohms.

Static resistance doesn't tell you anything, but operating current measured
with a DMM would tell you a lot.

>It would be expensive to change a blower motor on a whim, so, how
>would YOU suggest the blower motor be tested in situ?

I've never tested one, but I put a drop of turbine oil on the motor bearings
every five years or so. I do the same on the window and seat motors too.

I'd imagine if you listen carefully and have good hearing you can tell if the
motor is binding at all, but many people do not.

[Bimmer Owner]

On Wed, 20 Mar 2013 23:17:36 -0700, jim beam wrote:

> analyze the actual problem - don't just waste money replacing stuff.

That's exactly what we've done - yet - we need help since nobody to
date has figured out HOW to test an FSU that is fried.
http://www.bimmerfest.com/forums/showthread.php?t=678534

Note: It appears to be an active component, but it probably does
dissipate 100W.

[Bimmer Owner]

On Thu, 21 Mar 2013 08:14:12 -0700, jim beam wrote:

> it's cheaper to just buy a new one.

To be clear, that's what 99.99999999% of the BMW owners do.
But that's not the point of this thread.

The point of this thread is to get a handle on WHY they are all
failing.

Specifically, how to figure that out is the question.

[Bimmer Owner]

On Thu, 21 Mar 2013 11:45:54 -0400, Scott Dorsey wrote:

> Static resistance doesn't tell you anything, but operating current
> measured with a DMM would tell you a lot.

It 'can' be done, but would require a test jig inserted inline
as the FSU is deeply ensconced under the dash while the blower motor
is even more deeply so.

> I've never tested one, but I put a drop of turbine oil on the
> motor bearings every five years or so.

While that preventive work might be prudent, the sheer effort
to remove the entire dash simply to access the blower motor
would be problematic.

Still, if the problem is that the blower motor is merely using more
current as it gets older, why wouldn't a NEW FSU burn up within a
few weeks of insertion?

[Ismo Salonen]

On 03/21/2013 06:04 PM, Bimmer Owner wrote:
> Still, if the problem is that the blower motor is merely using more
> current as it gets older, why wouldn't a NEW FSU burn up within a
> few weeks of insertion?

If the unit is near its limits it might just get very hot and parts
start aging very fast -> semiconductors will just fail after a little
while. The new unit should fail sooner than the old one but who knows
who soon, maybe after a few years. Peugeot's ( and Citroen) used just
one huge pnp darlington which failed quite often , it was working too
near its operating limits.

(just my 2 cents)
ismo

[Scott Dorsey]

In article <kif3r7$252$1...@dont-email.me>, jim beam <m...@privacy.net> wrote:
>>
>> I don't see why it is so hard to unpot one of these things and repair them
>> directly, especially if it's a semiconductor failure. Put a bigger transistor
>> in there.
>
>unpotting is a nightmare - it will take much less time to build your own
>pwm controller. who knows, maybe you can switch the existing unit???!!!

Unpotting is fun, it's a nice change in the day to just sit down for a couple
hours with a dremel tool and a dental pick.

But I agree, building an aftermarket controller replacement would not be
a tremendously difficult thing to do, and it might be a highly profitable
one.

[Scott Dorsey]

Bimmer Owner <donta...@mymail.com> wrote:
>On Thu, 21 Mar 2013 09:47:31 -0400, Scott Dorsey wrote:
>
>> I don't see why it is so hard to unpot one of these things and repair them
>> directly, especially if it's a semiconductor failure.
>> Put a bigger transistor in there.
>
>Here are pictures from the last half dozen who tried that approach:
> http://www2.picturepush.com/photo/a/12470740/img/12470740.jpg
> http://www4.picturepush.com/photo/a/12470742/img/12470742.jpg
> http://www2.picturepush.com/photo/a/12470745/img/12470745.jpg
> http://www4.picturepush.com/photo/a/12470747/img/12470747.jpg
> http://www5.picturepush.com/photo/a/12470748/img/12470748.jpg
> http://www2.picturepush.com/photo/a/12470750/img/12470750.jpg

These are kind of sloppy jobs. But it's clear there are two TO-3 devices
there which have been removed in all of those photos.

>One problem with "put a bigger xtor" is that nobody on this planet
>has produced a decent circuit diagram of the FSU.

Well, has anyone got docs on that mystery IC there? It's from Elmos
Semiconductor, but it's not a standard Elmos part number on it, so it's
almost certainly a custom, since it doesn't look like anything in their
standard book.

[Scott Dorsey]

Bimmer Owner <donta...@mymail.com> wrote:
>On Thu, 21 Mar 2013 11:45:54 -0400, Scott Dorsey wrote:
>
>> Static resistance doesn't tell you anything, but operating current
>> measured with a DMM would tell you a lot.
>
>It 'can' be done, but would require a test jig inserted inline
>as the FSU is deeply ensconced under the dash while the blower motor
>is even more deeply so.

I don't know the wiring diagram on that particular model, so I don't know
where you would need to break in to measure just the current of the blower
without anything else. But it does not seem terribly insurmountable,
especially seeing that BMW is very good about breaking everything out into
connectors all over.

>> I've never tested one, but I put a drop of turbine oil on the
>> motor bearings every five years or so.
>
>While that preventive work might be prudent, the sheer effort
>to remove the entire dash simply to access the blower motor
>would be problematic.

Well, that's partly why I drive a 2002 and an E28, everything is much
easier to get to.

>Still, if the problem is that the blower motor is merely using more
>current as it gets older, why wouldn't a NEW FSU burn up within a
>few weeks of insertion?

You would expect that, indeed.

[tm]

"Scott Dorsey" <klu...@panix.com> wrote in message
news:kifmfo$7l$1...@panix2.panix.com...

> Bimmer Owner <donta...@mymail.com> wrote:
>>On Thu, 21 Mar 2013 11:45:54 -0400, Scott Dorsey wrote:
>>
>>> Static resistance doesn't tell you anything, but operating current
>>> measured with a DMM would tell you a lot.
>>
>>It 'can' be done, but would require a test jig inserted inline
>>as the FSU is deeply ensconced under the dash while the blower motor
>>is even more deeply so.
>
> I don't know the wiring diagram on that particular model, so I don't know
> where you would need to break in to measure just the current of the blower
> without anything else. But it does not seem terribly insurmountable,
> especially seeing that BMW is very good about breaking everything out into
> connectors all over.
>

Just measure the battery current with and without the blower running.

Turn every thing else off.


QED

[Bimmer Owner]

On Thu, 21 Mar 2013 16:59:01 -0400, tm wrote:

> Just measure the battery current with and without the blower running.
> Turn every thing else off.

That's a pretty good idea.

Of course, it's impossible to turn everything off, as the computer
won't go to sleep for 16 minutes after the car is shut and armed,
but, still - with the blower consuming something like 5 or 6 amps,
we should be able to measure at least that.

The problem, even with the car's additional electronics powered up,
is HOW MUCH of a difference are we expecting between an older blower
motor current draw and a new one?

Are we looking for a 1 amp difference, for example?

[mrob...@att.net]

Followups set to sci.electronics.repair .

In sci.electronics.repair Bimmer Owner <donta...@mymail.com> wrote:
> Does anyone have insight into what is the root cause (and repair) of
> the FSU failure that plagues almost every 1997 to 2003 BMW?

At a guess, one or both of the big power transistors that are inside the
FSU are failing. If the failure is that the blower motor doesn't run at
all, they are probably failing open. If the failure is either that the
blower motor runs at maximum speed, or a fuse blows, then they are
probably failing shorted. The blower motor probably draws more current
as it ages, and it may eventually be exceeding the power-handling
capability of the transistor(s). When the motor is switched off, it may
also generate a bit of a voltage spike, which may be above the voltage
rating of the transistor(s).

A possible solution is to replace the transistor(s) with ones with a
higher power rating in the same package. Another approach is to improve
the heat-sinking, maybe by adding metal to the existing fins. Or, cut
off the existing fins, bolt it to a huge slab of metal, and relocate the
entire thing away from the blower duct.

As a crutch, you could drop the voltage to the FSU a little bit. This
would slow down the blower, but also might tend to keep the voltages
and currents down to what the transistors can handle. You would need
to know the maximum current you would expect the FSU to draw; this
probably happens when the charging system voltage is at is maximum,
the blower motor is stone cold, and you turn it from "off" to "max".
Then, buy a big rectifier diode with a rating of a few amps more than
that, and splice it in to the power wire to the FSU. This will drop
the voltage by a volt or two all the time. Or, you could put a power
resistor in line instead; this will cause a variable voltage drop
depending on how much power the FSU and blower is drawing at the time.

Keep in mind that in the winter, keeping the windshield clear is a
safety function, so don't drop the blower speed too much.

> Also, does anyone have an idea HOW TO TEST a "repaired" FSU?

The tricky part depends on the nature of the control signal to the FSU.
If it's a simple analog voltage, that is easy to generate on the bench
with a potentiometer. If it's some kind of digital bus (CAN?), it is
*possible* to generate that on the bench, but it's probably easier to
get the dashboard heater control out of a junked car and let it generate
the signal.

To load the FSU, you can either use a power resistor that draws about
the same amount of current as the blower motor on "high" (a headlight
lamp might qualify), or an actual blower motor. The resistor will be
"better behaved" than a real motor.

For a power supply, it depends on how much current the blower motor
needs. You can get relatively inexpensive 13.8-volt power supplies in
ranges up to several amps, designed for running "12 V" equipment on the
bench. Samlex is one manufacturer but there are others. If it needs
more than 10 A or so, it's probably cheaper to just use a real car
battery and charge it when it's not being used.

You should probably arrange it so that there is some air blowing on the
FSU under test. If you are using a real blower motor, you can make a
duct out of cardboard. If not, use something like a 12 V computer case
fan to move a little air across the FSU.

It may also be interesting to have some kind of thermometer on the FSU
case while it is under test.

A good way to figure out what the FSU is actually doing is to probe a
working car with an oscilloscope. This will show you immediately how
the FSU is controlling the blower motor speed, as well as what the
control signal looks like. You can stick a straight pin *through* the
wire insulation as a test point, and then seal up the hole with
electrical tape or silicone sealant.

As has been mentioned, it would be also interesting to cut one of the
blower wires and measure the current drawn by the blower motor. For
extra credit, do this on a new car (or a newly-installed blower motor)
and then compare to a blower motor in a car that has just had its FSU
fail.

> The problem with replacing this ~$100 part is that the new replacement
> FSU fries itself just as often as the old one did, so you end up
> repeatedly replacing your fried FSU every few years or so.

On one hand, you would like stuff not to break. On the other hand,
spending $100 every two or three years on a car that starts around
$36,000 new is maybe not out of the realm of possibility. (Perspective:
that's one tire or 25 to 30 gallons of gas.)

These cars are apparently sold worldwide. If the FSUs sell for cheaper
in a lower-cost country, enough to offset shipping and taxes, import a
box full of them and make money. :)

Matt Roberds

[Ashton Crusher]

The simple answer is that they are under-designed for the conditions
under which they apparently are regularly subject to.

[Ashton Crusher]

If one replaces one of these perhaps it would be advisable to put a
fuse in the blower motor lines (it sounds like those can be gotten to
easily unlike the motor itself). If it's being blown by intermittent
high current draws the fuse could protect the $100 FSU. Another
option would be, at least for those who can live without the highest
blower setting and who think excess current draw is the culprit, would
be to put a power resistor in the blower motor line to limit the
current a bit. On the cheap pedestrian cars I drive the whole speed
control is just a trio of power resistors placed in the air flow to
help cool them. If they burn out (which is rare) they can sometimes
be fixed with a pop rivet.

[Bimmer Owner]

On Thu, 21 Mar 2013 15:03:45 -0700, Ashton Crusher wrote:

> If it's being blown by intermittent high current draws the
> fuse could protect the $100 FSU.

That's an interesting idea. The FSU supposedly consumes the
most power when the blower motor is set to the LOW settings
(simply because it has to dissipate the power as heat), so,
we could prevent excess current by fusing... say with a 10A
fuse, the blower motor (which is said to consume 5 to 6 A).

[Bimmer Owner]

On Thu, 21 Mar 2013 21:56:49 +0000, mroberds wrote:

> If the failure is that the blower motor doesn't run at all, they are
> probably failing open. If the failure is either that the blower motor
> runs at maximum speed, or a fuse blows, then they are probably failing
> shorted.

Actually, I was remiss in not stating that the blower motor generally
fails by acting weirdly, often said to "have a mind of its own", and,
most often by a parasitic current draw overnight that kills the battery.

[Mark]

> > If the failure is that the blower motor doesn't run at all, they are
> > probably failing open.  If the failure is either that the blower motor
> > runs at maximum speed, or a fuse blows, then they are probably failing
> > shorted.
>

i guess they call replacing a simple resistor with a bunch of
transistors.... "progress"

i'd replace the module with a bunch of power resistors and maybe a PTC
(self resetting) fuse

Mark


Mark

[Bimmer Owner]

On Thu, 21 Mar 2013 15:16:46 -0400, Scott Dorsey wrote:

> there are two TO-3 devices there which have been removed
> in all of those photos.

I don't know what a "TO-3" device is, but nobody removed anything
in those photos other than the goop that covered the circuit board.

> has anyone got docs on that mystery IC there? It's from Elmos
> Semiconductor, but it's not a standard Elmos part number on it

Focusing just on that Elmos Semiconductor AG IC from this thread:
http://www.bimmerfest.com/forums/showthread.php?t=309399
It looks like the PN is ELMOS, 10901D, 667A 1302A

It might be a generic or a special chip; I can't find it on the web:
http://www.elmos.com/produkte/automotive/motor-control/dc-motor-ics.html

[Bimmer Owner]

On Thu, 21 Mar 2013 21:56:49 +0000, mroberds wrote:

> It may also be interesting to have some kind of thermometer

> on the FSU case ...

That seems like an EXCELLENT idea, if we can put some kind
of temperature indicator in the FSU tines, then we can observe
what the temperature is in situ - which might tell us something
about what is overheating these things (assuming heat is the culprit).

[cl...@snyder.on.ca]

On Thu, 21 Mar 2013 16:59:01 -0400, "tm" <No_on...@white-house.gov>
wrote:

Just put your ammeter into the heater blower fuse connector and you
get the current of the blower motor.

[tm]

"Bimmer Owner" <donta...@mymail.com> wrote in message
news:kig343$pdf$2...@news.albasani.net...

Are you sure it is not already a pulse width regulator? Those transistors
look like they are TO-220 packages, not TO-3.
PWM has been around longer than SMT parts.

Maybe it is transients from the motor that are causing the failures.

Another place you could measure the current is by putting an ammeter in
place of the blower motor fuse.


tm

[cl...@snyder.on.ca]

So the crafty germans are using a high tech solid state resistor
instead of a PWM speed controller???

If I had one and it blew I think I'd be designing a PWM controller to
take it's place. Need to find out what kind of signal the controller
expects, but that shouldn't be too difficult.

[tra...@optonline.net]

On Mar 21, 5:58 pm, Ashton Crusher <d...@moore.net> wrote:
> On Thu, 21 Mar 2013 16:00:13 +0000 (UTC), Bimmer Owner
>

> <dontask...@mymail.com> wrote:
> >On Thu, 21 Mar 2013 08:14:12 -0700, jim beam wrote:
>
> >> it's cheaper to just buy a new one.
>
> >To be clear, that's what 99.99999999% of the BMW owners do.
> >But that's not the point of this thread.
>
> >The point of this thread is to get a handle on WHY they are all
> >failing.
>
> >Specifically, how to figure that out is the question.
>
> The simple answer is that they are under-designed for the conditions
> under which they apparently are regularly subject to.

That isn't necessarily the case. For example,t hey could be correctly
designed, rated for the application, etc but have a manufacturing
defect in just one of the components.

A better questions is why BMW apparently doesn't give a damn
to do the failure analysis to find out what's wrong. I have a friend
who has an X5 and had this problem with the blower resistors.
Even worse, the only symptom was it was draining the battery
and it took a huge number of hours to track it down.

While you're all wondering about that problem, might as well
add the fancy aux radiator fan to the list. This car had that go
and now the replacement one has failed again. And the
symptom there is, again, it drains the battery even when the
car is off. That fan is a real POS. Instead of just a simple
fan motor, it's a fan that's variable speed, driven by a PWM
signal. So, instead of just a motor, that fan sitting in front
of the hot radiator has electronics in it. A real genius of a
design. And for what? Like the fan can't just be on or off?
Only reason I can think of is that they want to save a few
watts of power to try to get better fuel economy. And for
that their customers get to shell out $500 for a new fan
every few years.

[tra...@optonline.net]

On Mar 21, 8:08 pm, cl...@snyder.on.ca wrote:
> On Thu, 21 Mar 2013 22:54:59 +0000 (UTC), Bimmer Owner
>

The dopes at BMW aren't any better at PWM's either.
They use a PWM signal to control the aux fan on the radiator.
You, know, the one that comes on if the cooling temp gets
too high or the AC is on, etc. Apparently just a simple on/off
motor wasn't good enough. So they made another one of
their German electronic miracle gadgets that's part of the
fan motor. That's right, electronics sitting right next to the
hot radiator.....

On the TV show All in The Family, the meathead was arguing
about Nixon and Watergate with Archie. Archie told the meathead
that Nixon's mistake was when it involved electronics, ie bugging,
taping, etc, that he should have used the Japanese, not Germans,
ie Haldeman, Ehrlichman, etc. I think Archie was on to something.

[bob haller]

On Mar 20, 11:08 pm, Bimmer Owner <dontask...@mymail.com> wrote:
> Does anyone have insight into what is the root cause (and repair) of the
> FSU failure that plagues almost every 1997 to 2003 BMW?

>  http://www.bimmerfest.com/forums/attachment.php?attachmentid=126060&d...

>
> Also, does anyone have an idea HOW TO TEST a "repaired" FSU?
>

> The "blower motor resistor", which also goes by FSR (Final Stage Resistor)
> or by FSU (Final Stage Unit), is known to fry itself in almost every single
> E46 (3-series), E39 (5-series), and E38 (7-series) BMW.
>  http://www.bimmerfest.com/forums/showthread.php?t=143393

>
> The problem with replacing this ~$100 part is that the new replacement FSU
> fries itself just as often as the old one did, so you end up repeatedly
> replacing your fried FSU every few years or so.

>  http://www.bimmerfest.com/forums/showthread.php?t=528566
>
> That's fine for most people (although the DIY is a PITA) - but I ask
> this newsgroup whether anyone has any insight into WHAT is actually
> breaking - and - why?
>  http://www.bimmerfest.com/forums/showthread.php?t=309399
>
> Here is the best (admittedly sketchy) wiring diagram we have so far:
>  http://www1.picturepush.com/photo/a/12467819/img/12467819.png

I had a dodge caravan that fried its heater AC motor speed control
resistor repeatedly....

the connector to the wiring harness detoriates from the high current
and the voltage drop causes the connector to heat up and the entire
assembly fails.

Oddly enough I repair roll laminators that apply plastic film to paper
think menus:)

laminators experience similiar failures so I did the following.

Purchased a new resistor block, soldered wires on all the connectors
putting a heavy wire on each one.... Put a pigtail on each one.
Installed resistor block. Its screwerd to the fire wall.

Cut the plug assembly off the harness, stripped all wires, twisted
them together and installed wire nuts on each one.

had the van for years with zero problems for this part:)

[jim beam]

On 03/21/2013 12:05 PM, Scott Dorsey wrote:
> In article <kif3r7$252$1...@dont-email.me>, jim beam <m...@privacy.net> wrote:
>>>
>>> I don't see why it is so hard to unpot one of these things and repair them
>>> directly, especially if it's a semiconductor failure. Put a bigger transistor
>>> in there.
>>
>> unpotting is a nightmare - it will take much less time to build your own
>> pwm controller. who knows, maybe you can switch the existing unit???!!!
>
> Unpotting is fun, it's a nice change in the day to just sit down for a couple
> hours with a dremel tool and a dental pick.

i'd rather repair light bulbs.

>
> But I agree, building an aftermarket controller replacement would not be
> a tremendously difficult thing to do, and it might be a highly profitable
> one.

well, it cost me about $18 in parts to retrofit the linear dash light
dimmer on my civic with a pre-built arduino unit. a custom unit could
come in substantially less than that, if in sufficient quantity.


--
fact check required

[jim beam]

On 03/21/2013 09:00 AM, Bimmer Owner wrote:
> On Thu, 21 Mar 2013 08:14:12 -0700, jim beam wrote:
>
>> it's cheaper to just buy a new one.
>
> To be clear, that's what 99.99999999% of the BMW owners do.
> But that's not the point of this thread.
>
> The point of this thread is to get a handle on WHY they are all
> failing.

i already told you - it's overheating. semiconductors don't like heat.

>
> Specifically, how to figure that out is the question.

knowing how the light bulb blew doesn't fix it.


--
fact check required

[jim beam]

On 03/21/2013 06:01 PM, tra...@optonline.net wrote:
> On Mar 21, 5:58�pm, Ashton Crusher <d...@moore.net> wrote:
>> On Thu, 21 Mar 2013 16:00:13 +0000 (UTC), Bimmer Owner
>>
>> <dontask...@mymail.com> wrote:
>>> On Thu, 21 Mar 2013 08:14:12 -0700, jim beam wrote:
>>
>>>> it's cheaper to just buy a new one.
>>
>>> To be clear, that's what 99.99999999% of the BMW owners do.
>>> But that's not the point of this thread.
>>
>>> The point of this thread is to get a handle on WHY they are all
>>> failing.
>>
>>> Specifically, how to figure that out is the question.
>>
>> The simple answer is that they are under-designed for the conditions
>> under which they apparently are regularly subject to.
>
> That isn't necessarily the case. For example,t hey could be correctly
> designed, rated for the application, etc but have a manufacturing
> defect in just one of the components.

but that's not going to apply to multiple different unit manufacturers,
over long periods of time.

>
> A better questions is why BMW apparently doesn't give a damn
> to do the failure analysis to find out what's wrong.

um, because it's a profit center? either they charge you $100 for a $6
unit, or you get fed up with the vehicle and buy a new one. that latter
is the psychology of their target market.

> I have a friend
> who has an X5 and had this problem with the blower resistors.
> Even worse, the only symptom was it was draining the battery
> and it took a huge number of hours to track it down.
>
> While you're all wondering about that problem, might as well
> add the fancy aux radiator fan to the list. This car had that go
> and now the replacement one has failed again. And the
> symptom there is, again, it drains the battery even when the
> car is off. That fan is a real POS. Instead of just a simple
> fan motor, it's a fan that's variable speed, driven by a PWM
> signal. So, instead of just a motor, that fan sitting in front
> of the hot radiator has electronics in it. A real genius of a
> design. And for what? Like the fan can't just be on or off?

indeed - a very good point. which begs the question, if they can pwm
the aux fan, wtf can't they do it with the blower fan???

> Only reason I can think of is that they want to save a few
> watts of power to try to get better fuel economy. And for
> that their customers get to shell out $500 for a new fan
> every few years.

bmw are designed, root and branch, to be expensive to maintain and own
after the warranty period. they spend a lot of money on r&d to achieve
that. and even more on advertising to convince their target that the
extra cost is justified for membership of the "ultimate marketing
tagline" club.


--
fact check required

[jim beam]

On 03/21/2013 08:22 AM, Nate Nagel wrote:
> On 03/21/2013 10:41 AM, jim beam wrote:
>> On 03/21/2013 06:59 AM, Nate Nagel wrote:
>>> On 03/21/2013 09:55 AM, jim beam wrote:
>>>> On 03/21/2013 04:52 AM, Nate Nagel wrote:

>>>>> On 03/21/2013 06:55 AM, the will wrote:
>>>>>> Blower motor drawing too much amperage taking it out. Change the
>>>>>> blower motor anytime?
>>>>>>
>>>>>

>>>>> My thought as well. Have you measured current draw on a new blower
>>>>> motor and compared it to one that is installed in a car where the FSU
>>>>> has failed? that would tell you whether there's any merit to this
>>>>> idea
>>>>> or not.
>>>>
>>>> for an "engineer", you're simply not of this planet.
>>>>
>>>
>>> Did you have any suggestions for the OP, or did you just show up to
>>> snipe without contributing anything as per usual?
>>
>> <https://groups.google.com/group/rec.autos.tech/msg/1870e822d74b0a5c?dmode=source&output=gplain&noredirect&pli=1>
>>
>
>
> link times out?

then use the message id within the link, retard.


>
>>
>> retard.
>>
>>
>>>
>>> You do know that most electrical/electronic components have a maximum
>>> current rating, yes? And that electric motors tend to draw more current
>>> when the bearings are going or they are otherwise subjected to loads
>>> higher than that for which they were designed? Does any of this sound
>>> remotely familiar to you?
>>
>> don't lecture me on electronics nate.
>
> ooh, or what? ITG gonna kick my ass? Sorry, I'm more interested in
> helping the OP than your delicate little feelers.

no, don't lecture me on stuff that you clearly don't have the first clue
about.

see above. retard.


>
>>>
>>> Really, what the will suggested seems to be a logical first step.
>>
>> if you don't know what the FUCK you're doing and don't know how to use a
>> dvm.
>>
>
> WTF is that supposed to mean?

it means that, if you know what you're looking at, a dvm can tell you
most of what you need to know here.


>
> OP can dissect the thing all he wants but it doesn't do him a damn bit
> of good to know *what* has failed unless he knows *why* it failed.

all he needs to know, retard, is that the unit failed and that he needs
to replace it. just like a light bulb.

more than that though, i also told the op how they can go about
establishing a permanent solution, but you're too fucking retarded to
read that or understand it.


--
fact check required

[jim beam]

On 03/21/2013 04:12 PM, Bimmer Owner wrote:
> On Thu, 21 Mar 2013 21:56:49 +0000, mroberds wrote:
>
>> It may also be interesting to have some kind of thermometer
>> on the FSU case ...
>
> That seems like an EXCELLENT idea,

won't save the unit, just a frozen motor.

> if we can put some kind
> of temperature indicator in the FSU tines, then we can observe
> what the temperature is in situ - which might tell us something
> about what is overheating these things (assuming heat is the culprit).

you can run the unit out of the fan housing - hold it in your hand and
you'll soon find out if it's getting hot or not.


--
fact check required

[jim beam]

On 03/21/2013 08:57 AM, Bimmer Owner wrote:
> On Wed, 20 Mar 2013 23:17:36 -0700, jim beam wrote:
>
>> analyze the actual problem - don't just waste money replacing stuff.
>
> That's exactly what we've done - yet - we need help since nobody to
> date has figured out HOW to test an FSU that is fried.
> http://www.bimmerfest.com/forums/showthread.php?t=678534

it's like testing a dead light bulb.


>
> Note: It appears to be an active component, but it probably does
> dissipate 100W.

it dissipates Vd x Im where Vd = voltage drop across the unit output,
and Im = current drawn by motor. it will indeed get hotter when running
the motor slower because of the greater voltage drop across the unit.
that's why pwm is the better solution - the semiconductors are either
fully on [minimal heat dissipation] or fully off [minimal heat
dissipation]. the only time they get to dissipate heat is during
switching which is a sub-millisecond event and a tiny percentage of the
base time.


--
fact check required

[jim beam]

what he said.


--
fact check required

[jim beam]

indeed.


--
fact check required

[Nate Nagel]

On 03/21/2013 10:07 PM, jim beam wrote:
> On 03/21/2013 09:00 AM, Bimmer Owner wrote:
>> On Thu, 21 Mar 2013 08:14:12 -0700, jim beam wrote:
>>
>>> it's cheaper to just buy a new one.
>>
>> To be clear, that's what 99.99999999% of the BMW owners do.
>> But that's not the point of this thread.
>>
>> The point of this thread is to get a handle on WHY they are all
>> failing.
>
> i already told you - it's overheating. semiconductors don't like heat.
>

Yeah, we know that.

*why* is it overheating?

>
>>
>> Specifically, how to figure that out is the question.
>
> knowing how the light bulb blew doesn't fix it.

But it may make the replacement last longer.

nate

--
replace "roosters" with "cox" to reply.
http://members.cox.net/njnagel

[Scott Dorsey]

All the standard Elmos part numbers begin with an E.

My guess is that the number on the chip is 10901D and that the other
two numbers are date and batch codes.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[jim beam]

On 03/21/2013 07:23 PM, Nate Nagel wrote:
> On 03/21/2013 10:07 PM, jim beam wrote:
>> On 03/21/2013 09:00 AM, Bimmer Owner wrote:
>>> On Thu, 21 Mar 2013 08:14:12 -0700, jim beam wrote:
>>>
>>>> it's cheaper to just buy a new one.
>>>
>>> To be clear, that's what 99.99999999% of the BMW owners do.
>>> But that's not the point of this thread.
>>>
>>> The point of this thread is to get a handle on WHY they are all
>>> failing.
>>
>> i already told you - it's overheating. semiconductors don't like heat.
>>
>
> Yeah, we know that.
>
> *why* is it overheating?

because it's linear, retard. if you don't know what they means, fuck
off until you find out.

>
>>
>>>
>>> Specifically, how to figure that out is the question.
>>
>> knowing how the light bulb blew doesn't fix it.
>
> But it may make the replacement last longer.

putting facts in front you dumb ass all day long doesn't make you any
smarter.


--
fact check required

[Bimmer Owner]

On Thu, 21 Mar 2013 19:15:16 -0700, jim beam wrote:

> that's why pwm is the better solution

Does pulse width modulation cause radio EMI?

[jim beam]

it can if the radio isn't very noise resistant and the switching is
"hard". you won't typically hear it on the fm bands, but you might on
the am.

you can make a pwm unit "soft switch" and kill pretty much all of the
electrical noise it would otherwise generate and incur only a very small
heating penalty.


--
fact check required

[Nate Nagel]

On 03/21/2013 10:25 PM, jim beam wrote:
> On 03/21/2013 07:23 PM, Nate Nagel wrote:
>> On 03/21/2013 10:07 PM, jim beam wrote:
>>> On 03/21/2013 09:00 AM, Bimmer Owner wrote:
>>>> On Thu, 21 Mar 2013 08:14:12 -0700, jim beam wrote:
>>>>
>>>>> it's cheaper to just buy a new one.
>>>>
>>>> To be clear, that's what 99.99999999% of the BMW owners do.
>>>> But that's not the point of this thread.
>>>>
>>>> The point of this thread is to get a handle on WHY they are all
>>>> failing.
>>>
>>> i already told you - it's overheating. semiconductors don't like heat.
>>>
>>
>> Yeah, we know that.
>>
>> *why* is it overheating?
>
> because it's linear, retard. if you don't know what they means, fuck
> off until you find out.

so "because it's linear" it by nature overheats to the point of failure?
Odd, I'm pretty sure that that controller worked initially on, well,
all of the vehicles in which it was originally installed.

The question is, is it overheating to the point of failure because the
designer cut things too fine (in which case designing a better part
would be the right approach), or is it because there's another issue
somewhere else *causing* a part that would otherwise have acceptable
service life to fail (in which case replacing it with a stock
replacement and fixing the underlying issue would be the most economical
thing to do)?

>
>
>>
>>>
>>>>
>>>> Specifically, how to figure that out is the question.
>>>
>>> knowing how the light bulb blew doesn't fix it.
>>
>> But it may make the replacement last longer.
>
> putting facts in front you dumb ass all day long doesn't make you any
> smarter.

IKYABWAI.

It would really be just like you to spend all day designing a more
robust controller, building it, watching it too burn up, and then
realize that the problem was something else, like a chronic problem with
dry fan motor bushings, windings dragging on the case, something like that.

But sure, don't check the obvious stuff, just go into your long-winded
sometimes technically correct and sometimes not babble, I know that
anything I say won't stop you anyway.

[Scott Dorsey]

In article <kigfbd$nq7$2...@dont-email.me>, jim beam <m...@privacy.net> wrote:
>On 03/21/2013 07:23 PM, Nate Nagel wrote:
>>
>> *why* is it overheating?
>
>because it's linear, retard. if you don't know what they means, fuck
>off until you find out.

Nothing wrong with linear motor control, it's just inefficient and
produces a lot of heat. I used to work in a place with a 1.2 MW DC
motor whose field coil voltage was controlled by a couple rooms full
of cast-iron resistors. The resistance array lasted nearly 80 years
before the whole facility was taken down.

As long as you keep within the safe operating area of the semiconductors,
you're fine. If you exceed them, bad things happen. But we don't know
if the semiconductors are failing on these things, or if it's just
ordinary RoHS solder failures; the RoHS crap doesn't like thermal cycling
so well.

[Scott Dorsey]

It can if it's not properly filtered. And the reason why I think beam is
correct about this being a linear control is that there is no filtration
in there.

My guess is that the cost of proper filtering and shielding makes the pwm
controller cost more than the linear controller in this case, which is
probably why they went the linear route.

[jim beam]

On 03/21/2013 07:53 PM, Nate "anosognosic" Nagel bleated:
<snip drivel>

>
> It would really be just like you to spend all day designing a more
> robust controller, building it, watching it too burn up, and then
> realize that the problem was something else,

um, no, it would be me building something that worked first time. and
that has stayed working.

but you wouldn't know that because you're an unspeakable hamster brained
retard that hasn't got the slightest clue the FUCK they're talking
about, much less the ability to click on a link and READ it.

> like a chronic problem with
> dry fan motor bushings, windings dragging on the case, something like that.

which are entirely fucking different, and don't fucking disappear after
the controller has been changed.

>
> But sure, don't check the obvious stuff, just go into your long-winded
> sometimes technically correct and sometimes not babble, I know that
> anything I say won't stop you anyway.

i wish something would stop you. like self-awareness.


--
fact check required

[jim beam]

On 03/21/2013 08:08 PM, Scott Dorsey wrote:
> In article <kigfbd$nq7$2...@dont-email.me>, jim beam <m...@privacy.net> wrote:
>> On 03/21/2013 07:23 PM, Nate Nagel wrote:
>>>
>>> *why* is it overheating?
>>
>> because it's linear, retard. if you don't know what they means, fuck
>> off until you find out.
>
> Nothing wrong with linear motor control, it's just inefficient and
> produces a lot of heat.

right, but what's the point in using 140W to run a 60W motor? and
/certainly/ not when the devices to do so are so cheap and abundant. i
can see doing it back in the day when there weren't any other options,
but today there are, and there have been for 20+ years.

> I used to work in a place with a 1.2 MW DC
> motor whose field coil voltage was controlled by a couple rooms full
> of cast-iron resistors. The resistance array lasted nearly 80 years
> before the whole facility was taken down.
>
> As long as you keep within the safe operating area of the semiconductors,
> you're fine. If you exceed them, bad things happen.

right. but again, we're dealing with mba's here. as an engineer,
you're going to design with reliability and a safety margin built in.
as an mba, you're going to cut and keep cutting until it meets "business
objectives".

> But we don't know
> if the semiconductors are failing on these things, or if it's just
> ordinary RoHS solder failures; the RoHS crap doesn't like thermal cycling
> so well.

very true. but at the end of the day, that's still heat. and a linear
semiconductor controller is just stooopid when a wire coil will do the
same job more reliably and at a fraction of the cost.


--
fact check required

[jim beam]

On 03/21/2013 08:10 PM, Scott Dorsey wrote:
> Bimmer Owner <donta...@mymail.com> wrote:
>> On Thu, 21 Mar 2013 19:15:16 -0700, jim beam wrote:
>>
>>> that's why pwm is the better solution
>>
>> Does pulse width modulation cause radio EMI?
>
> It can if it's not properly filtered. And the reason why I think beam is
> correct about this being a linear control is that there is no filtration
> in there.

it's the heat sink that's the dead give-away. a pwm controller heatsink
would be 1/10th the capacity. or less.

>
> My guess is that the cost of proper filtering and shielding makes the pwm
> controller cost more than the linear controller in this case, which is
> probably why they went the linear route.

i think the cost of that honking great heatsink significantly exceeds
the cost of a couple of extra inductors and caps.


--
fact check required

[Bimmer Owner]

On Thu, 21 Mar 2013 20:01:20 -0400, clare wrote:

> Just put your ammeter into the heater blower fuse connector and you
> get the current of the blower motor.

That's an interesting idea.

http://www3.picturepush.com/photo/a/12475041/img/12475041.jpg

The fuse for the blower motor is called the "infamous F76" for a reason.
http://bimmerfest.com/forums/showthread.php?t=674612

It's a 40 amp fuse under the glovebox but it's in a really inaccessible
spot; however, it's right side up, so, the wires going INTO it are
visible from the tips of your feet under the glove box.

So that's a possibility; but you'd have to cut the wires.
http://www5.picturepush.com/photo/a/12475043/img/12475043.jpg

[Ashton Crusher]

On Thu, 21 Mar 2013 22:54:59 +0000 (UTC), Bimmer Owner
<donta...@mymail.com> wrote:

>On Thu, 21 Mar 2013 15:03:45 -0700, Ashton Crusher wrote:
>
>> If it's being blown by intermittent high current draws the
>> fuse could protect the $100 FSU.
>
>That's an interesting idea. The FSU supposedly consumes the
>most power when the blower motor is set to the LOW settings
>(simply because it has to dissipate the power as heat), so,
>we could prevent excess current by fusing... say with a 10A
>fuse, the blower motor (which is said to consume 5 to 6 A).

Hmm, it did look like it had quite a heat sink. I had assumed it used
PWM to change speed, which should not generate much heat but my
assumption might be wrong (or my understanding of PWM...) A solid
state design that gets hot on purpose seems like a poor design to me.

[tra...@optonline.net]

On Mar 21, 10:25 pm, klu...@panix.com (Scott Dorsey) wrote:

If you google for 10901D it comes back with hits to
Chinese chip brokers that show it as an Elmos 16
pin surface mount chip. Which is consistent with what's
in the picture of the failed module, it has 16 pins.
But I could not find any data sheet on the part either.

[Bimmer Owner]

On Fri, 22 Mar 2013 05:20:37 -0700, tra...@optonline.net wrote:

> If you google for 10901D it comes back with hits to Chinese chip brokers
> that show it as an Elmos 16 pin surface mount chip.

I found the same. The chip is listed here:
http://www.jotrin.com/product/parts/10901D

But there is no datasheet there.

[Bimmer Owner]

On Fri, 22 Mar 2013 05:20:37 -0700, tra...@optonline.net wrote:

> If you google for 10901D it comes back with hits to Chinese chip brokers
> that show it as an Elmos 16 pin surface mount chip.

I found a Russian language description of it here:
http://tinyurl.com/crg2sms
http://kazus.ru/schematics/electrical-engineering/search/go/?text=%D0%C5%C3%D3%CB%DF%D2%CE%D0%20ELMOS%2010901D&nohistory=1&h=1

[Bimmer Owner]

On Fri, 22 Mar 2013 12:31:09 +0000, Bimmer Owner wrote:

> I found a Russian language description of it here:
> http://tinyurl.com/crg2sms

Here is a google translation

REGULATOR ELMOS 10901D
Car Voltage Regulator
Category: Car
Source: Radioland country Electronics
Temperature controller cabin air KAMAZ

Source: Plans radiokonstruktsy
Simple Temperature compensated voltage regulator.
Controller together with thyristor-transistor electronic ignition unit
with a long spark, ensuring the rapid start-ups at various operating
conditions, allowed to increase battery life of up to nine years.

Source: For the life of a soldering iron ...
Regulator for automotive windshield

Source: MASTER KIT
The controller measures the wiper-this control is designed to use regular mode switch blades and is contactless.

Source: For the life of a soldering iron ...
Temperature compensated voltage regulator device in some ways superior designs.
The controller can be used as a universal device is suitable not only for
mounting on any car, but everywhere, where the generator rotor speed is
variable (eg, wind power).
Choose the appropriate control elements, it can be easily adapted to work
with any voltage (up to 400V) and excitation current (tens of amperes).

Source: For the life of a soldering iron ...
Voltage regulator 2012.3702, 22.3702, 221.3702

Source: For the life of a soldering iron ...
Voltage regulator 201.3702

Source: For the life of a soldering iron ...
Voltage Regulator 13.3702

Source: For the life of a soldering iron ...
Voltage regulator RR132A, 1112.3702

[Bimmer Owner]

On Fri, 22 Mar 2013 12:31:09 +0000, Bimmer Owner wrote:

> I found a Russian language description of it here:

Googling for the Russian text, I find they appear to have
the same problem with the same FSU over here:
http://www.elektroda.pl/rtvforum/viewtopic.php?p=8838466#8838466

[jim beam]

you don't need to know this stuff any more than you need to know the gas
excitation voltage in a broken fluorescent tube. because you're not
going to unpot the thing and replace the chip. because it's probably
not the chip in the first place.

not trying to be rude - just trying to get you focused on the relevant
stuff - that the two options are:

1. continue replacing the existing [under-rated, low tech] unit.
2. build and deploy a pwm unit instead.

#1 is really not /that/ expensive, particularly if you factor in time,
even if it is part of the bmw marketing susceptibility tax.

#2 is a much better time investment - it certainly has a much better
return than figuring out that the existing unit is not repairable later
rather than sooner.


--
fact check required

[jim beam]

On 03/21/2013 09:31 PM, Bimmer Owner wrote:
> On Thu, 21 Mar 2013 20:01:20 -0400, clare wrote:
>
>> Just put your ammeter into the heater blower fuse connector and you
>> get the current of the blower motor.
>
> That's an interesting idea.
> http://www3.picturepush.com/photo/a/12475041/img/12475041.jpg
>
> The fuse for the blower motor is called the "infamous F76" for a reason.
> http://bimmerfest.com/forums/showthread.php?t=674612
>
> It's a 40 amp fuse

you don't want to try and use a 10/20A meter in the slot of a 40A fuse.
you probably already know that, but just saying.

> under the glovebox but it's in a really inaccessible
> spot; however, it's right side up, so, the wires going INTO it are
> visible from the tips of your feet under the glove box.
>
> So that's a possibility; but you'd have to cut the wires.
> http://www5.picturepush.com/photo/a/12475043/img/12475043.jpg
>

--
fact check required

[andrew s]

jim beam wrote on Fri, 22 Mar 2013 07:04:19 -0700:

> #1 is really not /that/ expensive, particularly if you factor in time,
> even if it is part of the bmw marketing susceptibility tax.

I don't know how many bmws are out there, but let's say it's a million
and then multiply that million by 100 dollars, and then let's see how
much it is in terms of expense.

[tra...@optonline.net]

On Mar 21, 11:22 am, Bimmer Owner <dontask...@mymail.com> wrote:
> On Thu, 21 Mar 2013 03:55:47 -0700, the will wrote:
> > Blower motor drawing too much amperage taking it out.
> > Change the blower motor anytime?
>
> This is an interesting approach, given that the vast majority of
> bimmer owners do NOT replace the blower motor - they replace the FSU.
>
> While the blower motor replacement procedure is a major PITA, one
> 'can' test the leads from the FSU harness connector pins #5 and #1
> which are power and ground respectively to the blower motor.
>
> Again, we don't have a circuit diagram, but it has been said that
> the blower motor takes about 6 amps (variously, depending on the speed)
> but it would take a test jig to test that in operation.
>
> To my knowledge, nobody has created that test jig (although I know
> of only one attempt, which failed):http://www.bimmerfest.com/forums/showthread.php?t=678534&highlight=fsu
>
> It's easy enough to test the resistance of the blower motor though,
> and those results have come out at about 0.4 to 0.6 ohms.
>
> It would be expensive to change a blower motor on a whim, so, how
> would YOU suggest the blower motor be tested in situ?

If it's just a typical DC motor with two leads, apply 12V and
it should run full speed. You could also measure how many amps it
draws when running. That is, IF it's just an ordinary motor.

[cl...@snyder.on.ca]

Why would you have to cut the wires????
Simply remove the fuse and connect the ammeter. You guys make your
lives so difficult

[tra...@optonline.net]

> lives so difficult- Hide quoted text -
>
> - Show quoted text -

It's kind of amazing the fuse is 40 amps, no? I mean a 1 hp
motor draws ~1500W And this heater blower is 480W?
Seems like a lot to me.....

[jim beam]

in this thread it's been said it draws 6A running. x 12V, that's 72W.

but the reason you have 40A is you have very high current start-up
transients. on a cold day with a gale blowing outside the car, and some
snow in the system, you could be into the 30's without too much problem.
so you need an amperage that will still blow in the event of short
circuit, but which will tolerate the above.


--
fact check required

[R. Mark Clayton]

Have you got a link to these "common problems" you keep posting about?


"Bimmer Owner" <donta...@mymail.com> wrote in message
news:kidtio$bco$1...@news.albasani.net...
> Does anyone have insight into what is the root cause (and repair) of the
> FSU failure that plagues almost every 1997 to 2003 BMW?
> http://www.bimmerfest.com/forums/attachment.php?attachmentid=126060&d=1194115994

=========

> Almost every BMW E39 (5-series) and E38 (7-series) and E46 (3-series)
> has shorts that develop in the trunk wiring loom - all in the same spot!

[Wild_Bill]

I think it's already been suggested, but if the car were my own vehicle, I'd
be content with a multi-position switch for the blower motor.. this is a
very reliable method.

A heavy duty switch and some over-rated power resistors would likely outlast
many replacement OEM miracle-in-a-box modules.

The parts, wire, a cover for the hole where the original removed module was,
and a Saturday afternoon would likely cover the cost investment.

I'm fairly certain that there are off-the-shelf variable speed modules that
would be an adequate replacement for an automotive blower motor application.

--
Cheers,
WB
.............


"jim beam" <m...@privacy.net> wrote in message
news:kiho9f$960$1...@dont-email.me...

[Clive]

In message
<acc3106a-224e-4a7c...@v8g2000yqe.googlegroups.com>,
"tra...@optonline.net" <tra...@optonline.net> writes
> Instead of just a simple
>fan motor, it's a fan that's variable speed, driven by a PWM
>signal.
If by PWM you mean pulse width modulation, then it would allow for
variable speed, but a DC motor is an inductive load and is not sensibly
controlled by such a system unless there is something in the circuit to
allow the peak voltage generated by the motor at pulse cut of to be
shunted to earth.
--
Clive

[tra...@optonline.net]

On Mar 23, 6:48 am, Clive <cl...@yewbank.demon.co.uk> wrote:
> In message
> <acc3106a-224e-4a7c-a17e-69cfe3e13...@v8g2000yqe.googlegroups.com>,
> "trad...@optonline.net" <trad...@optonline.net> writes> Instead of just a simple

> >fan motor, it's a fan that's variable speed, driven by a PWM
> >signal.
>
> If by PWM you mean pulse width modulation, then it would allow for
> variable speed, but a DC motor is an inductive load and is not sensibly
> controlled by such a system unless there is something in the circuit to
> allow the peak voltage generated by the motor at pulse cut of to be
> shunted to earth.
> --
> Clive

That "something" could be as simple as a diode. PWM is
commonly used to vary the power to a motor. BMW, for
example, uses it on the aux fan motor of the X5. And I
would suspect that it's also used for the blower motor
because you wind up wasting a lot less power that way.
And every little bit of power saved adds up and effects MPG.

[tra...@optonline.net]

On Mar 22, 7:42 pm, "R. Mark Clayton" <nospamclay...@btinternet.com>
wrote:

> Have you got a link to these "common problems" you keep posting about?
>

> "Bimmer Owner" <dontask...@mymail.com> wrote in message

>
> news:kidtio$bco$1...@news.albasani.net...
>
> > Does anyone have insight into what is the root cause (and repair) of the
> > FSU failure that plagues almost every 1997 to 2003 BMW?

> >http://www.bimmerfest.com/forums/attachment.php?attachmentid=126060&d...

>
> =========
>
>
>
> > Almost every BMW E39 (5-series) and E38 (7-series) and E46 (3-series)

> > has shorts that develop in the trunk wiring loom - all in the same spot!- Hide quoted text -

>
> - Show quoted text -

I don't have a link, but we had the blower resistor widget
go on an X5 here. And the aux cooling fan motor has gone
twice. There are plenty of threads online about many people having
those problems. Oh, and don't forget the
nice X5 feature where the cable that they use to hold up the
windows snaps, sending the window crashing down inside
the door, breaking it into a million pieces. Had that happen
twice too, once while the car was just sitting in the driveway.
Other time was driving down the highway.

Then there are their defective rubber parts. Like the boot on
the intake manifold that cracks in just a few years. Or the
CV joint boots. I've had lots of cars with CV boots and
only on the X5 do they fail every 20K miles. I've seen Honda CRVs
that went 200K miles with no failure.

[Clive]

In message
<b15e9629-0f65-4f53...@7g2000yqy.googlegroups.com>,
"tra...@optonline.net" <tra...@optonline.net> writes

>That "something" could be as simple as a diode. PWM is
>commonly used to vary the power to a motor. BMW, for
>example, uses it on the aux fan motor of the X5. And I
>would suspect that it's also used for the blower motor
>because you wind up wasting a lot less power that way.
>And every little bit of power saved adds up and effects MPG.

I agree with all you say.
--
Clive

[jim beam]

On 03/21/2013 08:08 PM, Scott Dorsey wrote:

> In article <kigfbd$nq7$2...@dont-email.me>, jim beam <m...@privacy.net> wrote:
>> On 03/21/2013 07:23 PM, Nate Nagel wrote:
>>>
>>> *why* is it overheating?
>>
>> because it's linear, retard. if you don't know what they means, fuck
>> off until you find out.
>
> Nothing wrong with linear motor control, it's just inefficient and
> produces a lot of heat. I used to work in a place with a 1.2 MW DC
> motor

that must have been interesting - what did that motor do?

> whose field coil voltage was controlled by a couple rooms full
> of cast-iron resistors.

that must have been a sight to see too.

> The resistance array lasted nearly 80 years
> before the whole facility was taken down.

shipped to china? or replaced by pwm controllers?

>
> As long as you keep within the safe operating area of the semiconductors,
> you're fine. If you exceed them, bad things happen. But we don't know
> if the semiconductors are failing on these things, or if it's just
> ordinary RoHS solder failures; the RoHS crap doesn't like thermal cycling
> so well.
> --scott
>


--

fact check required

[jim beam]

ancient news - controller designers and semiconductor manufacturers have
been on top of this from day 1.


--
fact check required

[jim beam]

serious question - why did you buy it?


--
fact check required

[Clive]

In message <kif8k1$ddg$2...@news.albasani.net>, Bimmer Owner
<donta...@mymail.com> writes

>It's easy enough to test the resistance of the blower motor though,
>and those results have come out at about 0.4 to 0.6 ohms.

Motors are not just a resistive load though.
--
Clive

[cl...@snyder.on.ca]

On Sat, 23 Mar 2013 10:48:27 +0000, Clive <cl...@yewbank.demon.co.uk>
wrote:

PWM is the most common method of controlling the speed of DC motors -
a flywheel diode is part of the "system" to handle the inductive
kick-back. Virtually all battery operated variable speed power tools
use PWM. So do virtually all electric bicycles with brush motors and
the vast majority of electric forklifts.

In fact, just about any application of a brush type DC motor that
requires reasonable speed control has switched to PWM control of some
sort over the last 20 years, including power wheel chairs (except
those using 3 phase brushless motors)

[Michael A. Terrell]

jim beam wrote:
>
> it means that, if you know what you're looking at, a dvm can tell you
> most of what you need to know here.


Sure it can, if you're nothing more than a low grade grease monkey.


> fact check required


Your checks always bounce.

--

Politicians should only get paid if the budget is balanced, and there is
enough left over to pay them.

Sometimes Friday is just the fifth Monday of the week. :(

[Michael A. Terrell]

Take a blown fuse and use it for a test connector with a cheap
50-0-50A meter. Then you can just plug it in in place of the fuse to
make the test. You won't even have to worry about the polarity. You
can use a high current shunt, & a digital meter if you want more
accuracy.

[Michael A. Terrell]

Bimmer Owner wrote:
>
> On Thu, 21 Mar 2013 15:03:45 -0700, Ashton Crusher wrote:
>
> > If it's being blown by intermittent high current draws the
> > fuse could protect the $100 FSU.
>
> That's an interesting idea. The FSU supposedly consumes the
> most power when the blower motor is set to the LOW settings
> (simply because it has to dissipate the power as heat), so,
> we could prevent excess current by fusing... say with a 10A
> fuse, the blower motor (which is said to consume 5 to 6 A).


It should generate less heat at low speeds, if it is PWM.

[cl...@snyder.on.ca]

Or just get the special tester that is made to plug into the
fuseblock. Autel makes the MX101 and 201 (10 amp and 20 amp) units for
the lighter duty stuff.

[Michael A. Terrell]

tm wrote:
>
> "Bimmer Owner" <donta...@mymail.com> wrote in message

> news:kig343$pdf$2...@news.albasani.net...

> > On Thu, 21 Mar 2013 15:03:45 -0700, Ashton Crusher wrote:
> >
> >> If it's being blown by intermittent high current draws the
> >> fuse could protect the $100 FSU.
> >
> > That's an interesting idea. The FSU supposedly consumes the
> > most power when the blower motor is set to the LOW settings
> > (simply because it has to dissipate the power as heat), so,
> > we could prevent excess current by fusing... say with a 10A
> > fuse, the blower motor (which is said to consume 5 to 6 A).
> >
>

> Are you sure it is not already a pulse width regulator? Those transistors
> look like they are TO-220 packages, not TO-3.


I've seen 20W power resistors in TO-220 packages.


> PWM has been around longer than SMT parts.
>
> Maybe it is transients from the motor that are causing the failures.
>
> Another place you could measure the current is by putting an ammeter in
> place of the blower motor fuse.
>
> tm

[Michael A. Terrell]

Is that cheaper than roll your own?

[Scott Dorsey]

Michael A. Terrell <mike.t...@earthlink.net> wrote:

>tm wrote:
>>
>>
>> Are you sure it is not already a pulse width regulator? Those transistors
>> look like they are TO-220 packages, not TO-3.
>
> I've seen 20W power resistors in TO-220 packages.

It does indeed look like a TO-220 from the pin spacing (since there are no
actual transistors in the photos, just spots from which they were removed).

But if it had been a PWM device, there would have been some filtering in
there, inductors and capacitors to keep the noise from getting into the
power lines. Designing clean and quiet PWM controllers is not quite as
trivial as some folks have made it out to be.

>> PWM has been around longer than SMT parts.
>>
>> Maybe it is transients from the motor that are causing the failures.

This is possible, if it is the transistors that are failing. I don't see
any big protection diodes in there either.

If it's a RoHS soldering issue, though, I would not be surprised.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Jamie]

A few car manufacturers use resistor wire in the harness leading to
the motor connection at the blower box.

This lowers the Q significantly giving you a voltage drop of course,
but it also reduces electrical noise and helps suppress the wheeling
voltages.

Blower motors in this case are normally designed to operate lets say
8 volts for example, for full RPM.

I learned this years ago when going through the pain of removing the
blower in an air box of a Chrysler product, only to find there was
nothing wrong with the motor. Symptoms led on to the fact there was
since the output of the speed control circuit was alive and happy but
no obvious connection to the motor. If I had unplugged it from the air
box before pulling that all apart, I would of noticed it.

The problem was the resistor wire in the harness which had open at the
crimp point, also in the harness.

Jamie

[jim beam]

On 03/20/2013 09:13 PM, jim beam wrote:

> On 03/20/2013 08:08 PM, Bimmer Owner wrote:
>> Does anyone have insight into what is the root cause (and repair) of the
>> FSU failure that plagues almost every 1997 to 2003 BMW?
>>

>> http://www.bimmerfest.com/forums/attachment.php?attachmentid=126060&d=1194115994
>>
>>
>> Also, does anyone have an idea HOW TO TEST a "repaired" FSU?
>>
>> The "blower motor resistor", which also goes by FSR (Final Stage
>> Resistor)
>> or by FSU (Final Stage Unit), is known to fry itself in almost every
>> single
>> E46 (3-series), E39 (5-series), and E38 (7-series) BMW.
>> http://www.bimmerfest.com/forums/showthread.php?t=143393
>>
>> The problem with replacing this ~$100 part is that the new replacement
>> FSU
>> fries itself just as often as the old one did, so you end up repeatedly
>> replacing your fried FSU every few years or so.
>> http://www.bimmerfest.com/forums/showthread.php?t=528566
>>
>> That's fine for most people (although the DIY is a PITA) - but I ask
>> this newsgroup whether anyone has any insight into WHAT is actually
>> breaking - and - why?
>> http://www.bimmerfest.com/forums/showthread.php?t=309399
>>
>> Here is the best (admittedly sketchy) wiring diagram we have so far:
>> http://www1.picturepush.com/photo/a/12467819/img/12467819.png
>>
>
> that looks like a linear semiconductor controller - an incredibly
> antiquated concept for a modern car.

well, you live and learn. apparently the reason they use a linear
controller is because it allows the fan to run near silently at low
speed. with pwm control the fluctuating magnetic fields in the motor
coils cause it to vibrate and make a humming noise at the pwm control
frequency.

that doesn't of course get around the fact that the unit in question
here is apparently badly under rated, but the above does at least
explain why it's used.


>
> old resistor packs for fans were open wire that sat in the fan's air
> stream for cooling. they were generally very reliable if their alloy
> wasn't too susceptible to salt.
>
> that unit looks like it still sits in the air stream with that honking
> great heat sink and i estimate it's trying to dissipate >100W. that can
> only mean it's a linear controller because a modern pwm device can
> control high motor currents with very little heat dissipation <10W.
>
> bottom line, a linear controller is always going to get hot and end up
> frying itself over time. the only thing you can do is either replace it
> with another unit that will ultimately meet the same fate, or undertake
> a significant modification.
>
> for the latter, you can try putting an even bigger heat sink on it - but
> i doubt there's a lot extra room available. you can also "pwm" it. i
> built a similar unit to deal with a linear controller over-heat issue on
> my 89 civic.
>
> <http://www.flickr.com/photos/38636024@N00/5068043855>
> <http://arduino.cc/en/Tutorial/PWM>
>
> depending on how much time you want to spend on a project like that, pwm
> can control superbly and offers benefits like motor speed not being so
> susceptible to supply voltage [engine idle voltage drop] etc.
>
> the down side of pwm is that it can generate electrical noise. [poor
> stereo installations can be particularly susceptible.] the ideal
> solution is to implement pwm with "soft switching", but that's getting
> quite advanced.
>
>


--
fact check required

[amdx]

>> that looks like a linear semiconductor controller - an incredibly
>> antiquated concept for a modern car.

>well, you live and learn. apparently the reason they use a linear
>controller is because it allows the fan to run near silently at low
>speed. with pwm control the fluctuating magnetic fields in the motor
>coils cause it to vibrate and make a humming noise at the pwm control
>frequency.

>that doesn't of course get around the fact that the unit in question
>here is apparently badly under rated, but the above does at least
>explain why it's used.

I see many Motor Speed Control Manufacturers upped their PWM
frequency to be between 16 K to 22 K to eliminate much of the noise.
Mikek

[tm]

"amdx" <am...@knologynotthis.net> wrote in message
news:41097$514f2120$18ec6dd7$30...@KNOLOGY.NET...

That would also make the LPF very much smaller.

Even going to 40 to 60 kHz makes the magnetics smaller. We still do not know
what is under the PCB for that unit.

tm

[cl...@snyder.on.ca]

On Sun, 24 Mar 2013 02:28:00 -0400, "Michael A. Terrell"

Definitely not, if you already have a multimeter - but it is easier
for the guys who can't figure out how to do it without butchering the
wiring harness.

[Jamie]

Sure, if you don't mind heating the motor up...

Jamie

[Michael A. Terrell]

That type shouldn't be allowed to own any tools. They generally do
more damage than good. If they do get something to work, it rarely lasts
because they have no clue what because the problem.

I've seen too many vehicles that some idiot cut and patched back
together. One stepvan I bought years ago had a damaged harness and I
talked them down almost $1000 on the price. It was coming off lease
from a fleet, and they wanted to fix it themselves. i pointed out that
if they could repair it properly, it wouldn't be in that condition.

[Michael A. Terrell]

Scott Dorsey wrote:
>
> Michael A. Terrell <mike.t...@earthlink.net> wrote:
> >tm wrote:
> >>
> >>
> >> Are you sure it is not already a pulse width regulator? Those transistors
> >> look like they are TO-220 packages, not TO-3.
> >
> > I've seen 20W power resistors in TO-220 packages.
>
> It does indeed look like a TO-220 from the pin spacing (since there are no
> actual transistors in the photos, just spots from which they were removed).

All those photos only show one side. I full reverse engineering
should be done to draw a full schematic but I've never had my hands on
that module. It would probably take a couple of them, because ot the
potting.

> But if it had been a PWM device, there would have been some filtering in
> there, inductors and capacitors to keep the noise from getting into the
> power lines. Designing clean and quiet PWM controllers is not quite as
> trivial as some folks have made it out to be.

Have you looked at the National Semiconductor (Now part of T.I)
'Simple Switcher' series of controllers? Generally only one inductor
and a couple small electrolytics. A lot simpler than older designs, and
little noise because of the small footprint.

> >> PWM has been around longer than SMT parts.
> >>
> >> Maybe it is transients from the motor that are causing the failures.
>
> This is possible, if it is the transistors that are failing. I don't see
> any big protection diodes in there either.
>
> If it's a RoHS soldering issue, though, I would not be surprised.
> --scott
>
> --
> "C'est un Nagra. C'est suisse, et tres, tres precis."

[Scott Dorsey]

In article <kin5r4$pi1$1...@dont-email.me>, jim beam <m...@privacy.net> wrote:
>
>well, you live and learn. apparently the reason they use a linear
>controller is because it allows the fan to run near silently at low
>speed. with pwm control the fluctuating magnetic fields in the motor
>coils cause it to vibrate and make a humming noise at the pwm control
>frequency.

Yes, this is why you put an integrator stage after the pwm stage, so that
the motor sees nice filtered DC with very little of the PWM leftover.

Problem is that the integrator stage costs money and big electrolytics
tend to have limited life, so auto folks don't like doing that.

>that doesn't of course get around the fact that the unit in question
>here is apparently badly under rated, but the above does at least
>explain why it's used.

It's a cheap, reliable way of doing the job, if it's done right. It's clear
that it wasn't done right, but I'm still waiting to hear what was done wrong.
Given all the RoHS-related failures and the report that touching up solder
joints on the transistors fixes the problem, I am suspicious that it's a
soldering issue made worse by the extreme temperature cycling.

[jim beam]

On 03/25/2013 06:59 AM, Scott Dorsey wrote:
> In article <kin5r4$pi1$1...@dont-email.me>, jim beam <m...@privacy.net> wrote:
>>
>> well, you live and learn. apparently the reason they use a linear
>> controller is because it allows the fan to run near silently at low
>> speed. with pwm control the fluctuating magnetic fields in the motor
>> coils cause it to vibrate and make a humming noise at the pwm control
>> frequency.
>
> Yes, this is why you put an integrator stage after the pwm stage, so that
> the motor sees nice filtered DC with very little of the PWM leftover.
>
> Problem is that the integrator stage costs money and big electrolytics
> tend to have limited life, so auto folks don't like doing that.

you don't want to integrate the output, merely rub the shoulders off the
square waves to get the harmonics down. the whole point and benefit of
pwm is that you have full voltage full power available in each pulse.
that's how you can start and control a motor with high torque at low
rpm. if you integrate or smooth out the motor's supply, you effectively
lose that and the motor won't start or torque the same way or even at all.

>
>> that doesn't of course get around the fact that the unit in question
>> here is apparently badly under rated, but the above does at least
>> explain why it's used.
>
> It's a cheap, reliable way of doing the job, if it's done right.

in this day and age, that's no longer true. motor control is one of the
hot ticket items on the silicon fab agenda, and has been for some time.
there are some great pwm options out there, and for not a lot of money.

> It's clear
> that it wasn't done right, but I'm still waiting to hear what was done wrong.
> Given all the RoHS-related failures and the report that touching up solder
> joints on the transistors fixes the problem, I am suspicious that it's a
> soldering issue made worse by the extreme temperature cycling.

you definitely have a point there, but given the size and shape of that
heat sink, i don't think there's any way that silicon is getting
sufficient cooling, and is clearly way up against its ceiling. whether
that's accident or design is another matter, but the bottom line is that
it's an issue that spans multiple different module manufacturers across
multiple continents with different internal designs - that reduces the
probability of it being rohs and slaps it firmly into the vehicle
manufacturer's lap.


--
fact check required

[jim beam]

interesting.


--
fact check required