Golden Rules of Troubleshooting

[Cursitor Doom]

Anyone care to share their experience on the correct approach to
troubleshooting? I'll kick off by suggesting:

1. Assume nothing.

Perhaps we can assemble a list of golden rules....

[N_Cook]

First analysis instrument to use on removing the case cover - your nose

[pf...@aol.com]

a) Assume nothing.
b) The nose knows.
c) The complexity of the problem is in inverse proportion to the symptoms displayed.
d) That one problem has been found and fixed does not imply that all problems have been either found or fixed.
f) First cause may be intermittent. What is observed may be secondary.

Peter Wieck
Melrose Park, PA

[Cydrome Leader]

smell test is good.

check power, fuses, probe around for expected voltages. For example if
there's any sort of linear regulator check output, input, check voltages
on ICs. I deal with old stuff so there's always some 7400 series logic so
+5 is expected to be all over the place.

Look for burned parts, puffy caps, probe anything in areas with
heat-discolored circit boards, check and resolder and suspect joints by
parts that warms up. Diode check is a great feature on DMMS.

If you're dealing with suspect dried up caps, just solder a new one on
the solder side of the board and see if that helps at all. I like to add
parts on the bottom of the board, get things working then position parts
where they belong if all good.

If these things appear OK, then you have to narrow the problem down and
dig around into what the circuit should do vs. what's happening.

For intermittent problems tap the hell of boards, cable assemblies etc.
Check power supply voltages with the device cold AND after it warms up.

Just came across a machine that would crash fairly often, The problem
appears to be a mix of loose sensor and power connectors, a power supply
that drops voltage as it warms up, plus a dead cooling fan in the
electronics section. Just to keep things interesting, nothing warms up
that much with the service panels removed.

[N_Cook]

There is problem with "twizzling" for intermittant soder joint failure,
if it is a PbF board. Its too easy to temporarily "fix" a failed joint.
I start with light touching stuff with a bird feather, while switched
on. Then firmer twizzling.
Then hot air or freezer spray.
Then if I auapect a PbF failure ,an adapted engraver tool with a shaped
nylon bolt in place of the engraving tip, to rattle the board, listening
on headphones , if an audio amp.

[Cydrome Leader]

I'm pleased to say I don't really deal with PbF stuff. How often do you
find bad joints that looked OK (well, as good as PbF looks) and did have
weird cracking or separating from the part lead?

Do you do repairs with real solder or that fake tin stuff?

[Jon Elson]

Well, usually that is a very good rule, and saves time chasing what you
THINK the problem must be, when in fact it is something novel you haven't
seen before.

But, then, I have repaired a few thing recently, where past experience told
me what the most likely failure was, and that was the correct thing to fix.

Jon

[Phil Allison]

** Troubleshooting is like a maze, there are many starting points and blind alleys to negotiate on your the way to the goal.

Unfamiliar equipment requires a more cautious approach than familiar items.

Always observe the fault carefully *before* starting disassembly and find out what functions work and what do not.

Owner's descriptions are often misleading or fail to mention important issues, but you still need to find out what prompted that description.

Bench tests need to simulate actual use or worst case use, but beware of simulating abuse.

When stuck on a problem, take a break and start over a day or so later.




.... Phil

[whit3rd]

On Monday, December 14, 2015 at 6:07:52 AM UTC-8, Cursitor Doom wrote:
> Anyone care to share their experience on the correct approach to
> troubleshooting?

Make a block diagram. It may only be a mental picture, but it's an important
step toward tracking a symptom down.

I taught a class of technicians once, from a local factory... the
block-diagram-exercise got them talking amongst themselves more
productively than any other lesson.

[Mark Zacharias]

This thread, to me, represents the best of what newsgroups like this are
for.

1. The aforementioned "assume nothing". (probably should have been ALL CAPS)

2. Correlate stated or observed malfunction with:
a.) Visual inspection and yes, often smell checks.
b.) Power supply checks.
c.) Again, check for mechanically intermittent connections.

3. Don't assume too much from DC voltage checks with a multimeter. A 'scope
can often give you the best "eyes" into what the circuit is actually doing.

Nevertheless, a good multimeter can give really great information
interpreting voltage drops, finding leaky or shorted nodes, bias issues,
etc.

Too many people just start off re-capping for example, assuming this fixes
almost everything. I'm sick to death of hearing this from customers who have
been on the internet.

Another thread here, I see...

Mark Z.

[Ken]

later." I cannot tell you how many problems I solved while doing that.
Sometimes getting just getting away from the problem allows clearer
thought.

[N_Cook]

Posting a query to some "social media" may not ellicit the solution but
some suggesting will often set you thinking in a different train. Its so
easy to decide in your own mind that the problem must be in some
particular narrow area and you totally overlook a completely valid
alternative area.

[Tim R]

Most important, assume nothing. As soon as you think you know what is wrong, it is impossible not to ignore contrary evidence.

I work with some engineers who are good designers because they keep their brain fixed on the goal and work through every obstacle. They THINK they are also good troubleshooters but they are wrong, obstinately frustratingly wrong, for the same reason. They KNOW what is wrong too early, and nothing shakes their belief.

Second. When anybody tells you the symptoms, listen. When they tell you why, STOP! Don't listen. It will probably be theoretically impossible, and then you end up doubting the symptoms. Sorry but this is especially a problem with techs and mechanics. They observe correctly but theorize contrary to the laws of physics, so you need to stop listening when they get to that point.

[John Robertson]

Capacitors?

<ducking>

I must confess we do replace almost all electrolytic caps that are more
than about 30 years old in our vintage game monitors and amplifiers
(video/pinball/jukebox) as this saves a tremendous amount of
troubleshooting time. It is true that perhaps 60% of the caps replaced
are fine, but the rest are marginal at best and make all sorts of errors
creep in that would take hours to find otherwise.

</ducking>

While we are in there we check resistors on
collectors/emitters/plates/cathodes as they often drift out of value.
However those we only change if off more than 10%

John :-#)#

--
(Please post followups or tech inquiries to the USENET newsgroup)
John's Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9
(604)872-5757 or Fax 872-2010 (Pinballs, Jukes, Video Games)
www.flippers.com
"Old pinballers never die, they just flip out."

[Ralph Mowery]

"John Robertson" <sp...@flippers.com> wrote in message
news:v72dnRqUANBaru3L...@giganews.com...

> Capacitors?
>
> <ducking>
>
> I must confess we do replace almost all electrolytic caps that are more
> than about 30 years old in our vintage game monitors and amplifiers
> (video/pinball/jukebox) as this saves a tremendous amount of
> troubleshooting time. It is true that perhaps 60% of the caps replaced are
> fine, but the rest are marginal at best and make all sorts of errors creep
> in that would take hours to find otherwise.
>
>

It all depends on the cost and how much later down time you want to take a
chance on.

At work we had a 200 HP motor drive control that quit and we called in a
factory repair man. He determined that 2 large diodes ( arund 600 volt and
100 amp or so) were bad. AS this was a 3 phase unit , there were 3 diodes.
I told him to replace the 3 rd one as it may have had some stress on it and
may fail later. He said he would but it was $ 50 for the diode. I told
him that at what we were paying him and the ammount of production it would
cost that $ 50 was nothing worth even thinking about.

[Ralph Mowery]

"Ken" <K...@invalid.com> wrote in message news:n4p0le$58i$1...@dont-email.me...

>>
> "When stuck on a problem, take a break and start over a day or so
> later." I cannot tell you how many problems I solved while doing that.
> Sometimes getting just getting away from the problem allows clearer
> thought.
>
>

That often works. If possiable after working on a problem for a while, as
someone else to take a look at it. Don't even tell him what you have done
or checked.

I found that it is beter for me when asked for help to not even listen to
what others have checked. It does pay to listen to see what parts they may
have changed out. Then check those parts to make sure they are good and
installed correctly.

I have done two things that rate as my worst boners. First was a problem
with a SCR temperature controler. Thought I had repaired it, but when
turning on the power it would blow a fuse. Did that 3 times and I just
could not understand it. The next fuse I installed, I checked it and it was
bad. Turned out when I checked the parts bin that half of the new ones were
bad.

Another one was when I replaced a part that came with about 20 feet of 5
wire cable of about # 20 wire. I used the old wire to pull the new wire
through the conduit. Some how I got distracted for a while and then when I
connected the wires, I had forgotten to cut off the old wire. That ment I
connected one end of the old wire back up and the other end was not
connected to anything. I asked someone else to see what it was that I had
done wrong as I knew it must be something simple that I over looked. He
took one look in the junction box and asked why there was so much wire in
it. Then found out what I had did wrong.

[jf...@my-deja.com]

On Tuesday, December 15, 2015 at 7:37:47 AM UTC-8, John Robertson wrote:
>
> Capacitors?
>
Back in the old days, McIntosh used to have clinics where owners could have their equipment restored up to specifications for free. I remember watching them start by routinely replacing all of the cathode bypass electrolytics; they would then check and replace the tubes, as neceeary. They rarely had to go farther (but would if required).

[Jeff Liebermann]

There is no correct approach. There are only approaches that work
under specific circumstances. Like the universal solution to all
problems, and the answer to all questions (42), the correct approach
are only useful after you found the solution.

1. That which you know to be functional, beyond any need of checking,
is usually the problem.

2. Solutions found after midnight are best forgotten as they are
likely to be the product of temporary insanity.

3. Things go better if you have a schematic, gallon of coffee, a
working unit to compare, and a parts unit to cannibalize.

4. While it is theoretically possible to work on two problems at one
time, it is much easier to fix problems in the order they appear. I
like to fix the little things first.

5. Nothing is considered fixed until after it is cleaned. If you
can't fix it, at least make it look like it's been fixed.

6. Approximately half the disassembly videos on YouTube are wrong,
useless, dangerous, or out of focus.

7. For a good collection of counterfeit parts, just buy them on eBay.

8. Your most valuable tool is a visual inspection, often with a
magnifying glass. This helps identify exploded, incinerated, or
overheated components. It also shows where the previous repairs were
performed, a sure sign of problems to come.

9. Always ignore the symptoms and theories of the customer. They're
often misleading and will usually waste your time chasing down false
theories. Test the unit yourself to confirm the symptoms. I often
find a very different set of problems or that the buzzwords in the
original description were misused.

10. Fix everything that you find, even if the customer hasn't
complained about it. If it's wrong, even slightly, they'll be back to
complain and you might end up fixing it for free.

11. Take photographs of before and after. Treat is as if it were
evidence in a lawsuit or insurance investigation. I also take a photo
of the insides of the customers laptop, and use it for wallpaper on
their desktop. The reactions are "interesting" and help fortify my
exorbitant rates. The photos also help when I can't recall how to put
it back together.

12. Never do what cannot be undone. For computahs, make an image
backup of the hard disk both before and after the repair. Image
backup programs are now very fast and Terabyte USB 3.0 hard disk
drives are cheap.

13. No repair is complete without a culprit. The first step to doing
a repair is to blame someone or something. This is an important part
of the repair as most customers are worried that they may have done
something wrong (such as buying a piece of junk). By blaming someone
else, this eases their guilty conscience.

14. Never let the customer see you reading the instruction manual.
They will immediately suspect that you don't know what you're doing.

15. Beware of spare parts left over after reassembly.

More later. I'm late (as usual).

--
Jeff Liebermann je...@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

[Cursitor Doom]

On Tue, 15 Dec 2015 07:37:42 -0800, John Robertson wrote:

> I must confess we do replace almost all electrolytic caps that are more
> than about 30 years old in our vintage game monitors and amplifiers
> (video/pinball/jukebox) as this saves a tremendous amount of
> troubleshooting time.

Does it, though? I mean, you could save even more time by just running
all the caps through an ESR meter test and just replacing those that
fail. Given how fragile some of those old PCB traces can be, I'd only
want to replace the caps that really way out of spec.

[John Robertson]

Um, we use temperature controlled soldering irons and the traces on most
of our arcade grade games stand several soldering cycles...

The Bob Parker design ESR meter (which we've been selling since 1999)
doesn't handle small value caps (under 10UFD) very well, and on the
monitors a bunch are 4.7ufd or less.

There are only about fifteen caps in the average monitor, and it takes
about an hour to pull the chassis, replace the caps, do the ring/LOPT
test, check the fuse, reinstall and start the burn-in process. Then it
goes away for five to ten years.

Amps can be worse, particularly early stereo tube amps where all the
parts are connected on standoffs - those can take three to five hours to
recap. They don't come back for ten to twenty years after a recap and
resistor check (tubes too of course).

[John-Del]

I used to do a local vendor's arcade monitors, and I can tell you that a cap that might pass an ESR test may destroy the vertical output on power up when left to sit in an unheated warehouse a week or so during it's route rotation.

I always recapped arcade monitors because of the wild temp extremes they would often see.

[Jon Elson]

Jeff Liebermann wrote:


> 3. Things go better if you have a schematic, gallon of coffee, a
> working unit to compare, and a parts unit to cannibalize.
>

Oh wow! This one is up there with Murphy's law!

And, unless you are the manufacturer of said device, much of the above will
never be available.

Jon

[Cydrome Leader]

I've stared at well written service manuals (these actually exist, but
tend to be old) that just made no sense until the next day, or after a
break. Not a fan of touching service manuals with diry hands either.

[Cydrome Leader]

I helps to try to figure out what a device should do when it is working.
Extracting this information is sometimes really hard when people are
fixating on what's broken and keep talking in circles.

[Ralph Mowery]

"Cydrome Leader" <pres...@MUNGEpanix.com> wrote in message
news:n4q6qt$2tt$2...@reader1.panix.com...

>> I helps to try to figure out what a device should do when it is working.
> Extracting this information is sometimes really hard when people are
> fixating on what's broken and keep talking in circles.

I got a call at the plant I worked at from an equipment operator. When I
got there he said an indicator light would not come on. He had changed
bulbs and even swappend a glowing one with the one that would not come on to
show me it was not the bulb.

I asked him about the equipment as I did not know anything about it. He
said he presses one button and a light comes on , then he presses the second
button and another light comes on, but now the second light would not come
on. As this was just in a control room and the equipment could be located
anywhere in the plant I asked him several times about the equipment and all
I could get out of him was he just pressse the buttons and the lights should
come. He did not seem to know where the equipment was, just the indicator
lights..

[Jeff Liebermann]

On Tue, 15 Dec 2015 15:49:13 -0600, Jon Elson <jme...@wustl.edu>
wrote:

Gallons of coffee are available at your local supermarket.

I practice what I preach. If really want something to work, I buy 3
of them, and cannibalize one or two for parts to make one of them
work. I also buy or download the manuals:
<http://802.11junk.com/jeffl/pics/home/slides/BL-shop5.html>
Notice that there are three HP8620C sweep generators, and three
SSI/Wavetek 3000b service monitors in the photo.

If the schematics once existed, they will eventually appear on
someones web pile. The sellers of manuals seem to be very good at
obtaining obscure manuals. I've posed schematics for some of the
stuff I've helped design on my web pile. Much more difficult are
schematics with voltages and waveforms. That used to be standard
practice until about the 1970's, but has lost favor probably because
it requires the schematics to be printed in color.

[Ralph Mowery]

"Cydrome Leader" <pres...@MUNGEpanix.com> wrote in message

news:n4q6hr$2tt$1...@reader1.panix.com...

>
> I've stared at well written service manuals (these actually exist, but
> tend to be old) that just made no sense until the next day, or after a
> break. Not a fan of touching service manuals with diry hands either.

Where I worked we had a copy machine in the shop and I would usually copy
the important pages of the service manual to take with me. Usually had them
already copied in a book I kept so I could fine the important pages quick
and took a copy of that with me.

The electrical blue prints for much of the wiring and some equipment was on
a computer and we had a large plotter so could run off what we needed to
take with us.
Sometimes I would make notes on the copies and leave them in the electrical
cabinet, or just write inside the cabinet with a marking pen.

[Jeff Liebermann]

On Tue, 15 Dec 2015 07:37:42 -0800, John Robertson <sp...@flippers.com>
wrote:

>I must confess we do replace almost all electrolytic caps that are more
>than about 30 years old in our vintage game monitors and amplifiers
>(video/pinball/jukebox) as this saves a tremendous amount of
>troubleshooting time. It is true that perhaps 60% of the caps replaced
>are fine, but the rest are marginal at best and make all sorts of errors
>creep in that would take hours to find otherwise.

<http://802.11junk.com/jeffl/pics/repair/slides/bad-caps.html>
I also do pre-emptive replacements on caps. Worse, if I find a cap
that is bulging or fails an ESR test, I replace *ALL* the caps that
are the same brand and value. Also, if I find a string of parallel
caps, and one is bad, I automatically assume that all of them are
either bad, or will soon fail. That may seem extreme, but I spend
more time extracting and replacing motherboards boards than I do
fixing them. It's easier and cheaper to replace everything that is
suspicious, than to deal with returns, rework, complaining customers,
reputation issues, etc. If the customer returns with the same
problem, but from a different cap, I have to do the rework for free,
which wipes all my profit from the initial repair. Do it right and do
it all the first time.

However, it also helps to pay attention. Do you see a problem here?
<http://802.11junk.com/jeffl/crud/GX520-bad-caps.jpg>

[Sjouke Burry]

On 16.12.15 2:47, Jeff Liebermann wrote:
> On Tue, 15 Dec 2015 07:37:42 -0800, John Robertson <sp...@flippers.com>
> wrote:
>
>> I must confess we do replace almost all electrolytic caps that are more
>> than about 30 years old in our vintage game monitors and amplifiers
>> (video/pinball/jukebox) as this saves a tremendous amount of
>> troubleshooting time. It is true that perhaps 60% of the caps replaced
>> are fine, but the rest are marginal at best and make all sorts of errors
>> creep in that would take hours to find otherwise.
>
> <http://802.11junk.com/jeffl/pics/repair/slides/bad-caps.html>
> I also do pre-emptive replacements on caps. Worse, if I find a cap
> that is bulging or fails an ESR test, I replace *ALL* the caps that
> are the same brand and value. Also, if I find a string of parallel
> caps, and one is bad, I automatically assume that all of them are
> either bad, or will soon fail. That may seem extreme, but I spend
> more time extracting and replacing motherboards boards than I do
> fixing them. It's easier and cheaper to replace everything that is
> suspicious, than to deal with returns, rework, complaining customers,
> reputation issues, etc. If the customer returns with the same
> problem, but from a different cap, I have to do the rework for free,
> which wipes all my profit from the initial repair. Do it right and do
> it all the first time.
>
> However, it also helps to pay attention. Do you see a problem here?
> <http://802.11junk.com/jeffl/crud/GX520-bad-caps.jpg>
>
>

A blue one with a headache.

[Jeff Liebermann]

On Wed, 16 Dec 2015 03:27:36 +0100, Sjouke Burry
<burrynu...@ppllaanneett.nnll> wrote:

>> However, it also helps to pay attention. Do you see a problem here?
>> <http://802.11junk.com/jeffl/crud/GX520-bad-caps.jpg>

>A blue one with a headache.

The "bad-caps" is in the URL, so that's rather obvious. However,
that's the result, not the problem. The cause is quite obvious once
you see it. I posted the picture previously and Phil Allison caught
the problem almost instantly. I didn't.

[Allodoxaphobia]

On Tue, 15 Dec 2015 17:47:13 -0800, Jeff Liebermann wrote:
>
> However, it also helps to pay attention. Do you see a problem here?
> <http://802.11junk.com/jeffl/crud/GX520-bad-caps.jpg>

Either the (out of focus) black capacitors are installed backwards
or the board is mis-labled with the "+" signs.

Jonesy
--
Marvin L Jones | Marvin | W3DHJ.net | linux
38.238N 104.547W | @ jonz.net | Jonesy | FreeBSD
* Killfiling google & XXXXbanter.com: jonz.net/ng.htm

[Jeff Liebermann]

On 16 Dec 2015 03:21:01 GMT, Allodoxaphobia

<knock_you...@example.net> wrote:

>On Tue, 15 Dec 2015 17:47:13 -0800, Jeff Liebermann wrote:
>>
>> However, it also helps to pay attention. Do you see a problem here?
>> <http://802.11junk.com/jeffl/crud/GX520-bad-caps.jpg>

>Either the (out of focus) black capacitors are installed backwards
>or the board is mis-labled with the "+" signs.
>Jonesy

Yep, you got it. Electrolytic capacitors are identified by a wide
stripe on the negative end. To make it easy to hand insert
electrolytics, the PCB is usually silk screen with a wide white area
around the corresponding negative wire. Usually, except for this find
Dell motherboard, that marks the positive lead instead with a wide
white area. To their credit, they added "+" marks, which I missed.
Having replace plenty caps on boards where the negative terminal is
marked, I didn't think to look for the "+" sign, and so installed it
backwards. The computer actually ran for a day or so, before it
started acting funny and blew the tops open. I initially thought I
had a batch of bad caps, so I replaced them a 2nd time, inserting them
backwards again. I knew I was in trouble when the caps got rather
warm. In desperation, I posted the photo to this newsgroup and got an
instant response. Only then did I notice that the PCB silk screen
markings were backwards.

Like I said, it pays to pay attention when re-capping.

[Michael A. Terrell]

Jeff Liebermann wrote:
>
> However, it also helps to pay attention. Do you see a problem here?

> ?http://802.11junk.com/jeffl/crud/GX520-bad-caps.jpg?


85C?

[John Robertson]

On 12/15/2015 6:43 PM, Jeff Liebermann wrote:
> On Wed, 16 Dec 2015 03:27:36 +0100, Sjouke Burry
> <burrynu...@ppllaanneett.nnll> wrote:
>
>>> However, it also helps to pay attention. Do you see a problem here?
>>> <http://802.11junk.com/jeffl/crud/GX520-bad-caps.jpg>
>
>> A blue one with a headache.
>
> The "bad-caps" is in the URL, so that's rather obvious. However,
> that's the result, not the problem. The cause is quite obvious once
> you see it. I posted the picture previously and Phil Allison caught
> the problem almost instantly. I didn't.
>
>
>

Do you mean where someone mixed 85C caps (that failed) with 105C caps,
that look OK?

[John Robertson]

Oh...that was too obvious. Missed it!

John :-#(#

[jurb...@gmail.com]

>"Does it, though? I mean, you could save even more time by just >running all the caps through an ESR meter test and just replacing >those that fail. Given how fragile some of those old PCB traces can >be, I'd only want to replace the caps that really way out of spec. "

Not so much that, but the ones that matter. For example you could draw a graph of the dissipation of a vertical deflection IC (or transistors for that matter)against the ESR of the boost cap. Usually 100 - 330 uF in value these boost the Vcc to the ouptu stage during retrace. When the cap ESR rises the output circuit operates in linear mode longer to try and compensate. Usually, its dissipation is quite a bit higher before you see anything on the screen like a compression at the top or a foldover. It over heats and burns out and about 80 % of the time the tech finds it with a foldover after replacing the IC or transistors.

So there are CERTAIN ones you want to just replace or at least check. But things are out there with hundreds of caps and it might be impractical to change them all.

And another thing, I would highly recommend getting the unit working properly before recapping. Then, recap in steps, rechecking proper operation in between every one.

Maybe some people are lucky, but I have been where Murphy's law was strictly enforced. And Murphy himself told me "You make your own luck". (the story of Murphy is something I will post eventually but it belongs in another place)

[Dave Platt]

In article <1aj17bp99gqdjcv4v...@4ax.com>,

Jeff Liebermann <je...@cruzio.com> wrote:

>>> However, it also helps to pay attention. Do you see a problem here?
>>> <http://802.11junk.com/jeffl/crud/GX520-bad-caps.jpg>
>
>>A blue one with a headache.
>
>The "bad-caps" is in the URL, so that's rather obvious. However,
>that's the result, not the problem. The cause is quite obvious once
>you see it. I posted the picture previously and Phil Allison caught
>the problem almost instantly. I didn't.

Are *all* *four* of those large caps installed backwards?!?

Yah. Amazing you didn't have a chassis full of oily linguine there.

[Jon Elson]

Jeff Liebermann wrote:

> On Tue, 15 Dec 2015 15:49:13 -0600, Jon Elson <jme...@wustl.edu>
> wrote:
>
>>Jeff Liebermann wrote:
>
>>> 3. Things go better if you have a schematic, gallon of coffee, a
>>> working unit to compare, and a parts unit to cannibalize.
>
>>Oh wow! This one is up there with Murphy's law!
>>
>>And, unless you are the manufacturer of said device, much of the above
>>will never be available.
>
> Gallons of coffee are available at your local supermarket.
>

I know where to find coffee, although I don't drink it.

> I practice what I preach. If really want something to work, I buy 3
> of them, and cannibalize one or two for parts to make one of them
> work. I also buy or download the manuals:
> <http://802.11junk.com/jeffl/pics/home/slides/BL-shop5.html>
> Notice that there are three HP8620C sweep generators, and three
> SSI/Wavetek 3000b service monitors in the photo.
>

Manuals for test gear are usually available. But, for a lot of consumer
gear, automotive modules and industrial gear, they may NOT be! That can be
a real headache.

Old CNC control gear used to have fabulous manuals, with a theory manual
three times as big as the schematics.

But, on later gear, you were lucky to get drawings of the cables, some
configuration charts, and that was ALL that was ever allowed outside the
factory. So, you had to reverse engineer how a lot of stuff worked to
figure out what was wrong with it.

A woking unit to compare to is REALLY a huge help, when available.

Jon

[Shaun]

"Cursitor Doom" wrote in message news:n4miat$8a6$1...@dont-email.me...

Anyone care to share their experience on the correct approach to
troubleshooting? I'll kick off by suggesting:

1. Assume nothing.

2. If at first you don't succeed, destroy any evidence that you even tried!


3. Try Percussive maintenance first. If it works after you bang it, it has
intermitant connections, or components.


Shaun

[Shaun]

"Cursitor Doom" wrote in message news:n4miat$8a6$1...@dont-email.me...

Anyone care to share their experience on the correct approach to
troubleshooting? I'll kick off by suggesting:

1. Assume nothing.

Check all user accessible parts and power components, like transistors and
Diodes.
After the visual check of the components for burnt parts or over heated
parts and a smell test; I would flip the board over and inspect all the
solder joints usually with a magnifying lens and and check for cold or
fractured solder joints. When I'd find one I usually remove the old solder
with a solder sucker or wick and then re-solder the joint making sure the
component lead gets lots of heat during the solder process and I use real
solder. Parts or the board around components that got hot often had bad
solder joints from heating and cooling.

Shaun - serious post.

[pf...@aol.com]

Amen to that- the working unit to compare!

I finished the Dynaco ST120 from hell last night. It came to me "fuzzy in one channel". And it was.

First run-through: One output transistor in the 'good' channel, one output and one driver in the other, still fuzzy. I wound up ohming out every part, comparing to the good channel. Six drifted resistors later, I got to the 5.1V zener diode. Bingo. It had become a 94 ohm resistor.

Given that these beasts blow up by the numbers, I generally install sockets for the outputs, and do the TIP mod once ALL else is under control.

Peter Wieck
Melrose Park, PA

[Jeff Liebermann]

On Wed, 16 Dec 2015 11:34:43 -0800, dpl...@coop.radagast.org (Dave
Platt) wrote:

>In article <1aj17bp99gqdjcv4v...@4ax.com>,
>Jeff Liebermann <je...@cruzio.com> wrote:
>
>>>> However, it also helps to pay attention. Do you see a problem here?
>>>> <http://802.11junk.com/jeffl/crud/GX520-bad-caps.jpg>
>>
>>>A blue one with a headache.
>>
>>The "bad-caps" is in the URL, so that's rather obvious. However,
>>that's the result, not the problem. The cause is quite obvious once
>>you see it. I posted the picture previously and Phil Allison caught
>>the problem almost instantly. I didn't.

>Are *all* *four* of those large caps installed backwards?!?

Yep. When I do something wrong, I'm consistent. As I previously
ranted, when I find one bad cap of a type and value, I replace *ALL*
the caps of the same type and value. My time is more expensive than
the extra caps.

>Yah. Amazing you didn't have a chassis full of oily linguine there.

Actually, the machine ran quite nicely for a day or two the first time
I put the caps in backwards. Eventually, it started acting strangely
so I retreived it from the customers. All 4 caps were bulging. So, I
replaced all 4 caps again, putting them in backwards again. That's
when I noticed that they were getting hot, which prompted my initial
Usenet posting. I too would have expected at least a small explosion,
but nothing happened.

[John Robertson]

Nice that there were no explosions - I'm sure your customer would have
been nonplussed.

(ducking from the coffee explosion)

John ;-#)#

[Ralph Mowery]

"Jeff Liebermann" <je...@cruzio.com> wrote in message
news:ndt57bhk8bil21l66...@4ax.com...

>
> Yep. When I do something wrong, I'm consistent. As I previously
> ranted, when I find one bad cap of a type and value, I replace *ALL*
> the caps of the same type and value. My time is more expensive than
> the extra caps.
>
>>Yah. Amazing you didn't have a chassis full of oily linguine there.
>
> Actually, the machine ran quite nicely for a day or two the first time
> I put the caps in backwards. Eventually, it started acting strangely
> so I retreived it from the customers. All 4 caps were bulging. So, I
> replaced all 4 caps again, putting them in backwards again. That's
> when I noticed that they were getting hot, which prompted my initial
> Usenet posting. I too would have expected at least a small explosion,
> but nothing happened.

Interisting it ran at all.

It is easy to get into a bad pattern of doing things. A coworker and I were
repairing some flouresence lights in the plant. Got to one and put in new
tubes and it did not come on. This did not phase us as we often will get a
bad tube or so as there are thousands in the plant we often will replace
over 100 tubes in a day. Sometimes we get bad tubes so put in another set
and still no light. Decided it was the ballast, so replaced that. Still no
light. Knew we had power as there were about 20 other lights in the room.
Replaced the ballast 2 more times and sitll no light. This ballast had been
replaced before as there were several places where the wires were spliced
together with wire nuts. One would thing with only 8 wires it would be easy
to get it going. Got time to go home. I went up the next day by myself
and decided to try one more time. This time I removed all the wires and
instead of just going by the color of the wires, actually trace the wiring
out. This time it lite just fine.

What we were doing wrong was just matching the wire colors and as it had
been replaced before the colors did not go to the same place.

[Chuck]

Peter,

Who in their right mind would still be using one of these? They were
considered to be an awful amps back in the 70s. One I saw burned down
a house. The carbon resistors caught fire and there happened to be a
curtain draped across the top of the amplifier. After seeing this
amp, I refused to work on them.

---
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus

[Jeff Liebermann]

On Wed, 16 Dec 2015 20:13:52 -0600, "Shaun" <stereo...@gmail.com>
wrote:

>"Cursitor Doom" wrote in message news:n4miat$8a6$1...@dont-email.me...
>

>1. Assume nothing.

1a. Trust nobody (except your certificate authority).
1b. Believe no one.
1c. Presume nothing.
1d. Ignore fashionable explanations.
1e. Distrust authority.
1f. Ignore all advice.
1g. Test all new replacement components.

>2. If at first you don't succeed, destroy any evidence that you even tried!

I never make the same mistake twice. Five or six times is my average.

>3. Try Percussive maintenance first. If it works after you bang it, it has
>intermitant connections, or components.

Nope. Clean the device first. Depending on the type of filth, that
can be blowing off the dust with compressed air, or washing with a
household cleaner to remove fingerprints, dirt, crud, slime, food,
whatever. Cleaning allows you time to inspect the device, where you
might visually find the problem. Often, the problems go away with the
filth. Customers don't believe that anything has been repaired unless
it's clean.

Instead of beating on the box, try turning it upside down and shaking.
If you hear something rattle around, you've either found the problem,
or what's left of some component. Loose screws and spare parts on new
electronics are amazingly common.

[pf...@aol.com]

Ah, they ain't no how as bad as all that these days. Between the various mods, Factory and susequent, they have been rendered pretty bullet-proof, very stable, and as simple SS amps go, fairly melifluous. They were made in the uncounted tens of thousands, and uncounted thousands survive. With a few hours of simple work and not much cost, a decent 50+ watt amp may be had. As it happens, I keep two (full mods) that see very rough service, and have done so in one case for 2 years of 24/7 use in a desert climate, not conditioned. 100F+ from may to November. It now sits in my shop system seeing about 3 hours per week, these days.

Who would put a curtain over an amp capable of frying an egg in the first place?? That smacks of terminal idiocy.

[Cydrome Leader]

Give him credit for at least swapping out indicator bulbs.

[Cydrome Leader]

There always seems to come a point when people stop updating the stickers
inside the cabinet or the service books with all updates, past problems
and more importantly field modifications and why they were done. This
seems to happen around the time the safety switches start wear out and get
bypassed or panels and covers start to go missing.

[Jeff Liebermann]

On Tue, 15 Dec 2015 18:31:14 -0500, "Ralph Mowery"
<rmower...@earthlink.net> wrote:

>Sometimes I would make notes on the copies and leave them in the electrical
>cabinet, or just write inside the cabinet with a marking pen.

What? You don't like my method of documenting changes?
<http://members.cruzio.com/~jeffl/k6bj/K6BJ%20Repeater/slides/Documentation.html>
I think it's been like that since at least 2001.

Incidentally, I use a special ink for the purpose, that fades to
invisibility in about a year. It helps keep the manuals nice and
clean.

[Mark Zacharias]

<pf...@aol.com> wrote in message
news:a117378b-ecb2-4aaf...@googlegroups.com...

Personally I wouldn't use an ST-120 simply because I find capacitor-coupled
amps to sound muddy, and yeah - I hated working on the things. Piece of crap
really.

Prefer direct-coupled amps (with a competent protection circuit!) although I
do like an autoformer coupled McIntosh...

Mark Z.

[John-Del]

On Friday, December 18, 2015 at 7:37:37 AM UTC-5, Mark Zacharias wrote:

> Prefer direct-coupled amps (with a competent protection circuit!)

> Mark Z.

Funny how certain things trigger a memory of something forgotten for years. I had a Hitachi brand receiver that the customer said blew out several speakers on one side. I checked the outputs, nothing shorted so I hooked up some cheap TV speakers at low volume and there was no DC to speak of on either side and it was clean and clear. I let it run a couple of hours and suddenly there was a loud hum, pop, and one TV speaker that puked it's voice coil. This was direct coupled amp with no type of speaker protection. Ended up junking it.

[Cydrome Leader]

Jeff Liebermann <je...@cruzio.com> wrote:
> On Tue, 15 Dec 2015 18:31:14 -0500, "Ralph Mowery"
> <rmower...@earthlink.net> wrote:
>
>>Sometimes I would make notes on the copies and leave them in the electrical
>>cabinet, or just write inside the cabinet with a marking pen.
>
> What? You don't like my method of documenting changes?
> <http://members.cruzio.com/~jeffl/k6bj/K6BJ%20Repeater/slides/Documentation.html>
> I think it's been like that since at least 2001.

ha. Love the metal can transistor diagram. At least these aren't drawn on
paper bags or cardboard and then thrown away.

> Incidentally, I use a special ink for the purpose, that fades to
> invisibility in about a year. It helps keep the manuals nice and
> clean.

They should make heated pens for writing on thermal paper.

[Jeff Liebermann]

On Fri, 18 Dec 2015 20:31:53 +0000 (UTC), Cydrome Leader
<pres...@MUNGEpanix.com> wrote:

>Jeff Liebermann <je...@cruzio.com> wrote:
>> On Tue, 15 Dec 2015 18:31:14 -0500, "Ralph Mowery"
>> <rmower...@earthlink.net> wrote:
>>
>>>Sometimes I would make notes on the copies and leave them in the electrical
>>>cabinet, or just write inside the cabinet with a marking pen.
>>
>> What? You don't like my method of documenting changes?
>> <http://members.cruzio.com/~jeffl/k6bj/K6BJ%20Repeater/slides/Documentation.html>
>> I think it's been like that since at least 2001.

>ha. Love the metal can transistor diagram. At least these aren't drawn on
>paper bags or cardboard and then thrown away.

That scribbling wasn't one of mine. I usually draw an isometric
scribbling of the transistor or IC so that one can tell if it's a top
or bottom view. I think the red markings on the various drawings are
mine. Red is useful because it disappears when copied.

>> Incidentally, I use a special ink for the purpose, that fades to
>> invisibility in about a year. It helps keep the manuals nice and
>> clean.

>They should make heated pens for writing on thermal paper.

Ummm... They do. It's called a soldering iron. However, there's a
trick to using a soldering iron for writing. Be sure to grab the
correct end of the soldering iron. The rest is self evident and easy.

[Cydrome Leader]

Jeff Liebermann <je...@cruzio.com> wrote:
> On Fri, 18 Dec 2015 20:31:53 +0000 (UTC), Cydrome Leader
> <pres...@MUNGEpanix.com> wrote:
>
>>Jeff Liebermann <je...@cruzio.com> wrote:
>>> On Tue, 15 Dec 2015 18:31:14 -0500, "Ralph Mowery"
>>> <rmower...@earthlink.net> wrote:
>>>
>>>>Sometimes I would make notes on the copies and leave them in the electrical
>>>>cabinet, or just write inside the cabinet with a marking pen.
>>>
>>> What? You don't like my method of documenting changes?
>>> <http://members.cruzio.com/~jeffl/k6bj/K6BJ%20Repeater/slides/Documentation.html>
>>> I think it's been like that since at least 2001.
>
>>ha. Love the metal can transistor diagram. At least these aren't drawn on
>>paper bags or cardboard and then thrown away.
>
> That scribbling wasn't one of mine. I usually draw an isometric
> scribbling of the transistor or IC so that one can tell if it's a top
> or bottom view. I think the red markings on the various drawings are
> mine. Red is useful because it disappears when copied.

What the color of highlighter that would copy solid black even though you
could still read the original?

The copiers here are just color scanner/printers so they don't have the
same spectral sensitivity as the old machines so I can't test.

>>> Incidentally, I use a special ink for the purpose, that fades to
>>> invisibility in about a year. It helps keep the manuals nice and
>>> clean.
>
>>They should make heated pens for writing on thermal paper.
>
> Ummm... They do. It's called a soldering iron. However, there's a
> trick to using a soldering iron for writing. Be sure to grab the
> correct end of the soldering iron. The rest is self evident and easy.

Too hot and the thermal paper cycles back to white. It does weird things
when heated to the transition temp range.

[Jeff Liebermann]

On Fri, 18 Dec 2015 23:28:59 +0000 (UTC), Cydrome Leader
<pres...@MUNGEpanix.com> wrote:

>What the color of highlighter that would copy solid black even though you
>could still read the original?

I don't know and too lazy to test it on my copier.

Interesting stuff:
<http://www.protectedpaper.com/category_s/17.htm>

>The copiers here are just color scanner/printers so they don't have the
>same spectral sensitivity as the old machines so I can't test.

I have an (old) Canon PC785 mono copier which should work. However, I
don't have any highlighters to try.

>>>> Incidentally, I use a special ink for the purpose, that fades to
>>>> invisibility in about a year. It helps keep the manuals nice and
>>>> clean.
>>
>>>They should make heated pens for writing on thermal paper.
>>
>> Ummm... They do. It's called a soldering iron. However, there's a
>> trick to using a soldering iron for writing. Be sure to grab the
>> correct end of the soldering iron. The rest is self evident and easy.

>Too hot and the thermal paper cycles back to white. It does weird things
>when heated to the transition temp range.

Too hot and the paper catches fire. As I recall, the paper was black
or brown before it started burning. I just tried it with some thermal
receipt printer paper. It didn't go back to white.

[mrob...@att.net]

Cursitor Doom <cu...@notformail.com> wrote:
> Anyone care to share their experience on the correct approach to
> troubleshooting?

Maybe I've been hanging out around too many manager or business types,
but I'd suggest:

Find out if a working new (or used) example of the item in question
is available, and what it costs.

Under a certain amount, it won't pay to spend time fixing it, unless
there are some other circumstances involved. (It was grandma's radio,
or whatever.)

Between that amount and some other, really high amount, it might pay to
spend time fixing it.

Above that really high amount, they are either wanting confirmation that
it is broken, so they can persuade their boss to buy a new one, OR
hoping to blame you for an inability to fix it, so *you* have to buy the
new one.

Just because you're paranoid doesn't mean that they *aren't* out to get
you.

Matt Roberds

[jurb...@gmail.com]

>"OR
>hoping to blame you for an inability to fix it, so *you* have to buy >the
>new one. "

For that, they are going to need weapons. I mean like the government has.

[Ralph Mowery]

<mrob...@att.net> wrote in message news:n52ael$dqs$2...@dont-email.me...

> Cursitor Doom <cu...@notformail.com> wrote:
>> Anyone care to share their experience on the correct approach to
>> troubleshooting?
>
> Maybe I've been hanging out around too many manager or business types,
> but I'd suggest:
>
> Find out if a working new (or used) example of the item in question
> is available, and what it costs.
>
> Under a certain amount, it won't pay to spend time fixing it, unless
> there are some other circumstances involved. (It was grandma's radio,
> or whatever.)
>

That is the way I have looked at lots of things. The repair parts often
cost more than the origional item. At work there was a motor and gear box
of around 1/2 HP. To get a new motor or gear box actually cost within $ 5
of a whole new motor and gearbox. Then the company would have to pay the
mechanic over $ 40 an hour to rebuild the unit as they were always replaced
as a unit.

[MJC]

In article <n51qfp$jqc$1...@reader1.panix.com>, pres...@MUNGEpanix.com
says...

>
> They should make heated pens for writing on thermal paper.

Soldering iron?

Mike.

[jurb...@gmail.com]

MAKE NO PROMISES.

Ever.

[Wond]

On Sat, 19 Dec 2015 01:55:44 -0800, jurb6006 wrote:

> MAKE NO PROMISES.
>
> Ever.

Reminds me of that fellow, Ainit da Troot

[jurb...@gmail.com]

Yup, those words to not emit from my mouth or keyboard.

I have learned how to manage this planet. I also do not get pissed off unless it is really severe provocation. Aggravation is not a choice but anger is. If I kick you in the balls, whether you get pissed off or not you want to kick my ass. If you are not pissed off you want to do it to make the world a better place, which is the same reason I will shoot to kill if someone tries to rob me. But if a baby steps on your balls with those fucking cement baby shoes (no wonder they can't walk) you are not angry. If you can avoid anger in physical pain like that you got no excuse any other time. (I should probably teach an anger management class huh)

I try to do what I say I am gong to do, but II always allow for Murphy's Law. If I say I'll be there at noon I will plan to be there by eleven. Actually I say "I'll be there BY...", not "at".

When you learn electronics, especially service, you pick up a frew things.

My last good job, I go to boss and say I know what is wrong and we got the part. That is all I said, but that stupid fuck would schedule delivery for later that day. Sometimes I felt like cutting his goddam fingers off so he couldn't dial the phone. But see, if something went wrong he was the one to explain it to the customer. Fine with me.

And if they pissed me off I could look at the clock for a couple of minutes and see one more dollar in my pocket. Wanna say something about it I could go to the bathroom.

Got them by the balls, and after a little while they know it. In a way I was the boss. Order some of these, and we need this and that, and get this shit the fuck out of my way before I shoot it or take an axe to it. Some places, they asked ME what I wanted for lunch and they would go get it.

Well I gotta admit there is a reason for that lol.

Rich, a coworker, became a friend. I lived 25 miles from the shop and he lived twice as far. I rode with him to and from work for quite a while. then we sat at my house for a bit and got smoked a bit. We almost died together.

He had this Ford Escort and we were on I-90 in the fast lane, which is the correct lane because the exit to my house was on the left. A semi changed lanes and we were underneath it right along the dividing wall. An extremely stressful situation. He drove expertly and matched speed and piloted the thing perfectly, with the horn blaring all the time. Eventually the semi got out of the fast lane and I said "Get us to the nearest bar". He agreed.

Anyway, we got tight and one day we decided, since we were both "Electrasound graduates" where you DID go out for lunch, that we were going to the Ground Round for lunch.

The boss said "Don't go, you guys won't come back". We went, had surf n turf and a few beers and Rich says "I don't like how he was saying we won't come back". I said "Yeah". And then that lightbulb (a dim one) lit up and one of us said "Know what we should do ?". you know what happened then.

So we sat there for about an hour drinking and then decided to call the shop. Told the boss we need money because we cannot pay the tab ! That was a lie but fuck it. Told him we need someone to bring down about $50. The boss said "I can't leave, I am the only one here".

I have had some really bad times in life, and I have had some really good times in life. In some jobs, the employee is really the boss.

Like construction. Brick layers smoke pot and therefore cannot pass a drug test. Know what the union does here ? They hire one guy who does not smoke it and whether or not he can lay brick, he takes all the drug tests for everybody.

These brickies make around $30 an hour plus super benefits, and that is because they do something that not all that many people can do, at least at their level of performance. They are the boss. As a matter of fact, you offer most of them the foreman position they will refuse. My Father was a pretty damn good job shop machinist (worked with the engineers on the prototype for the first floppy disk making machine) and was offered management positions more than once. He said no, in fact he said fuck no. the reason ? Everyone bitches at you. you got the suits wanting shit that can't be done and employees you have a hard time getting to do what can be done. Middle management is not a good place all the time. And back then the labor market was such that you could not get 100 people to suck donkey dick for two bucks an hour. We had real industry and skilled people were important to the economy.

Things were different then. Now, money is made on paper. They even have paper gold. The world is junk.

One more good reason and I am ready to leave it. Honest Men with real skills have no place in this country anymore.

[John Robertson]

On 12/19/2015 2:53 PM, jurb...@gmail.com wrote:
> On Saturday, December 19, 2015 at 11:18:03 AM UTC-5, Wond wrote:
>> On Sat, 19 Dec 2015 01:55:44 -0800, jurb6006 wrote:
>>
>>> MAKE NO PROMISES.
>>>
>>> Ever.
>>
>> Reminds me of that fellow, Ainit da Troot
>
> Yup, those words to not emit from my mouth or keyboard.
>

> I have learned how to manage (on) this planet. I also do not get pissed off unless it is really severe provocation. Aggravation is not a choice but anger is. If I kick you in the balls, whether you get pissed off or not you want to kick my ass. If you are not pissed off you want to do it to make the world a better place, which is the same reason I will shoot to kill if someone tries to rob me. But if a baby steps on your balls with those fucking cement baby shoes (no wonder they can't walk) you are not angry. If you can avoid anger in physical pain like that you got no excuse any other time. (I should probably teach an anger management class huh)
>

I like your analogy - if your baby/child kicks you and you do not
respond with rage, then why when an adult does? Sounds like a good trick
for anger management.

Perhaps some world leaders (or would be leaders) need to think about that!

Thanks!

[Jeff Liebermann]

On Sat, 19 Dec 2015 01:55:44 -0800 (PST), jurb...@gmail.com wrote:

>MAKE NO PROMISES.
>Ever.

Ok, I promise not to make any more promises.


- If I did everything I promised to do, I'd never get anything done.

- Everyone lies, but that's ok, because nobody listens.

- Do unto others. Then run.

- Troubleshooting: Find the person giving you trouble and shoot them.

- Most embarrassing moment: When the Chinese clone works better
than the original.

- Election time: Promise the voters anything, and then do whatever
the opposition promised to do. It happens every 4 years.

[Cydrome Leader]

Jeff Liebermann <je...@cruzio.com> wrote:
> On Sat, 19 Dec 2015 01:55:44 -0800 (PST), jurb...@gmail.com wrote:

[stuff cut]

> - Most embarrassing moment: When the Chinese clone works better
> than the original.

Anybody have good stories of this?

[Jeff Liebermann]

No. I'm taking the 5th ammendment.
What you don't know, won't hurt me.

[Cydrome Leader]

Jeff Liebermann <je...@cruzio.com> wrote:
> On Mon, 21 Dec 2015 17:23:02 +0000 (UTC), Cydrome Leader
> <pres...@MUNGEpanix.com> wrote:
>
>>Jeff Liebermann <je...@cruzio.com> wrote:
>>> On Sat, 19 Dec 2015 01:55:44 -0800 (PST), jurb...@gmail.com wrote:
>>
>>[stuff cut]
>>
>>> - Most embarrassing moment: When the Chinese clone works better
>>> than the original.
>
>>Anybody have good stories of this?
>
> No. I'm taking the 5th ammendment.
> What you don't know, won't hurt me.

Ha.

Did the unnamed parties steal back some of the enhancements?

[Jeff Liebermann]

On Mon, 21 Dec 2015 21:02:55 +0000 (UTC), Cydrome Leader

<pres...@MUNGEpanix.com> wrote:

>Jeff Liebermann <je...@cruzio.com> wrote:
>> On Mon, 21 Dec 2015 17:23:02 +0000 (UTC), Cydrome Leader
>> <pres...@MUNGEpanix.com> wrote:
>>
>>>Jeff Liebermann <je...@cruzio.com> wrote:
>>>> On Sat, 19 Dec 2015 01:55:44 -0800 (PST), jurb...@gmail.com wrote:
>>>
>>>[stuff cut]
>>>
>>>> - Most embarrassing moment: When the Chinese clone works better
>>>> than the original.
>>
>>>Anybody have good stories of this?
>>
>> No. I'm taking the 5th ammendment.
>> What you don't know, won't hurt me.

>Ha.
>Did the unnamed parties steal back some of the enhancements?

Of course, with my help. But when they wanted some of the money they
paid me back, I diplomatically declined. Business ethics in many
parts of the planet are very different from the US.
[Q] What's the difference between a bribe and a commission?
[A] A bribe is paid in advance. A commission after. Otherwise,
they're the same.

I know of several other cloned products were are better than the
original, but I'm not talking and not worried. A fair chunk of my
income comes from what I euphemistically call "design reviews"[1].

There are also companies that can't even copy a product and get it
right. One favorite is a company that fired its outsourced designers,
only to find that the documentation they had supplied with the product
was fatally inaccurate. The company then had to reverse engineer their
own product. The resulting clone was dead on arrival. I was hired to
fix the problem without changing anything. Right. I traced the
problem to whomever measured the parts misreading the range setting on
the LRC meter. All the values were off by a factor of 10 because
someone had removed the range knob, and replaced it rotated by one
detent. It was obviously not an accident. After that was fixed, I
had to deal with an "improved" PCB that closely matched the schematic,
but not quite. The highlight of the project was when one employee,
with a very guilty conscience, offered me a bribe to not blame him for
any of the problems. I didn't take the money because I thought it
might be a trap. It wasn't.


[1] The difficult part is keeping a straight face. I once worked on
a BlueGoof wireless speaker system, where the designers had placed the
BT chip dead center in the middle of the PCB, located the chip antenna
nearby, and put a shield over both. Range was suppose to be about 30
meters minimum, but was only about 0.5 meters. I couldn't believe it,
but there it was. It was amazingly difficult for me to NOT burst out
laughing during my initial fee negotiations and artificially
protracted circuit analysis. I found plenty of other problems and
mistakes, so they got their money's worth.