And today's little bit of time-wasting lead-free nonsense ...
Arfa Daily
the Quad name on it, I wasn't even sure that they were still going. Anyway,
this thing always worked in that the amplifier kept producing output, but
there was, at the very least, a background 'rustle' and at worst an
alarmingly loud crackle, that can't have been doing the internal bass driver
any good. Not affected by volume setting, so output or PSU. Nothing really
conclusive to be seen on a 'scope. When it was doing it, you could 'see' it
virtually anywhere, including on the output stage power rails, which were
bouncing around all over the place. It had a 'feel' of an intermittent
output transistor about it. Nothing physical such as heat, cold or vibration
would provoke it, so I initially rejected thoughts of bad joints. There are
four output Tr's in it - 2 x PNP and 2 x NPN , paralleled up, so I removed
one pair. No difference. Still worked perfectly well, and still had the
random crackle. So I swapped the first two transistors back in. No change.
Some time was then spent trying to prove where the noise was coming from,
without any positive results, Eventually, I decided that it might actually
be a bad joint. There was no indication that the board was built with
lead-free solder, other than the fact that the joints were conical and dull.
I set about doing a blanket re-solder, and quickly ran into trouble. I don't
know what on earth sort of solder they had used, but even on small joints,
my temperature controlled bench iron was struggling. I even wound it up full
to 450 deg, and it still wasn't good. On larger joints like the smoothing
caps and the very chunky rectifier diodes, it wasn't having any of it at
all. Eventually, I had to dig out my 45 year old 140 watt Weller gun. At
least that made short work of reflowing the joints, but of course, you've
got to then be twice as careful about running joints into one another, as
the tip is really too big for this sort of job.
In the end, when it was all back together, it was silent, so I have to
conclude that it *was* a bad joint. But what makes it so frustrating from a
commercial 'let's make some money from this repair' point of view, is that
unlike conventional leaded solder joints when they go bad, you just can't
provoke lead-free bad joints to show themselves by any of the time-tested
and trusted methods.
I hate the stuff with a passion >:-(
Arfa
William Sommerwerck
This is one issue I won't disagree with you on. We're just seeing the
beginning of serious servicing problems.
N_Cook
news:Qnf4p.45514$837....@newsfe19.ams2...
Is one of your inducers an engraving tool with an insert of a nylon bolt
with "sharpened" end/tip? to pcb only , no direct contact to any SMD of
course as likely to flip them off.
Unfortunately you have to monitor the o/p with phones because of the noise
of the engraver. So what sort of solder do you think it was ? high Cu and
tin ? at those sorts of temp very high probability of temp induced Si
failures. Manufacture date?
JW
wrote in Message id: <Qnf4p.45514$837....@newsfe19.ams2>:
ObAOL: Me too! In the last few weeks alone I repaired several custom A/D
converter boards where they were inoperative until you put a slight
pressure a 44 pin PLCC dual port ram chip located between the micro and
the PLD. Looking at all the pins under a stereo microscope which has 25x
magnification revealed no bad solder joints, every joint looked flawless.
Yet when I resoldered the chip (with leaded solder) the boards worked
perfectly. I'd like to round up the folks who started this nonsense and
drop 'em in a large vat of molten no-lead solder, which is about the only
thing it'd be good for.
On the plus side, I have not yet seen any failures that could be
attributed to whisker growth.
JW
Message id: <iitj24$n0g$1...@news.eternal-september.org>:
Hi N_cook,
Have you ever noticed that your quoting is broken? If you're interested in
fixing it, check this web page:
http://home.in.tum.de/~jain/software/outlook-quotefix/
Arfa Daily
>>
>> In the end, when it was all back together, it was silent, so I have to
>> conclude that it *was* a bad joint. But what makes it so frustrating from
> a
>> commercial 'let's make some money from this repair' point of view, is
>> that
>> unlike conventional leaded solder joints when they go bad, you just can't
>> provoke lead-free bad joints to show themselves by any of the time-tested
>> and trusted methods.
>>
>> I hate the stuff with a passion >:-(
>>
>> Arfa
>>
>
> Is one of your inducers an engraving tool with an insert of a nylon bolt
> with "sharpened" end/tip? to pcb only , no direct contact to any SMD of
> course as likely to flip them off.
> Unfortunately you have to monitor the o/p with phones because of the noise
> of the engraver. So what sort of solder do you think it was ? high Cu and
> tin ? at those sorts of temp very high probability of temp induced Si
> failures. Manufacture date?
>
>
I tend to use a Biro pen, a hot air rework station (turned down to 100 deg
or so), a can of freezer, and the butt end of a bloody great screwdy. Oh
yes. And a lump hammer ... :-)
Seriously though, with normal leaded joints, I've never found it necessary
to use anything other than 'gentle' methods to pin a bad joint down to
within a square cm of board, which is what makes lead-free joint problems so
incredibly frustrating. I get them all the time where you've only got to
look sideways at the board, and the joint will go bad, and yet no amount of
provocation will bring it on when it's right, nor get it back when it's
wrong. And when you do eventually find it, the component is often hanging
out of the board - except you can't actually see that it is until you tug on
it, or come to re-solder it, when the solder flies away from the component
leg to form a ring on the pad, leaving the leg looking as though it's never
been soldered in its life ... And how many times do these lead-free bad
joint jobs bounce a couple of weeks later ? Can you imagine the implications
if the rotten stuff ever does find its way into avionics and other
life-preserving areas ? New programme on Discovery ? "Aircrash
Investigation - The Lead-Free Years" ?
As to the Quad. It was from their "Lite" series. The owner's user guide says
"03 - 05 Issue 1" inside its front cover so I'm guessing maybe 2005 ?? which
is before the 'official' lead-free introduction cut off point of June 2006,
but a number of manufacturers - notably Sony for instance - were
manufacturing with the stuff well in advance of that date. There is also a
note in the back cover about EC compliance requirements that it conforms to,
but they are about EMC and voltage safety. No mention of lead-free.
I suppose it's possible that the thing was not built with lead-free, but it
certainly looked and behaved like the stuff. Which brings us back to a point
often made by Mr Cook. How do you tell for sure when the board isn't
categorically marked ?
I really don't know what alloy had been used on this. Only that it had
trouble melting on the end of my normal continuous-use
temperature-controlled bench iron, even when set at max. It did melt ok with
the 140 watt Weller gun on it, but even with that, it only 'flowed' fairly
normally. Anyone who has ever used one of these beasts, will know that under
normal circumstances, a small joint will be pretty much boiled on the tip
...
Arfa
N_Cook
news:4tp4l6pmkg3pose3s...@4ax.com...
> On Tue, 8 Feb 2011 17:50:39 -0000 "Arfa Daily" <arfa....@ntlworld.com>
> wrote in Message id: <Qnf4p.45514$837....@newsfe19.ams2>:
>
> >A big heavy Quad sub. It's been so long since I've seen anything new with
> >the Quad name on it, I wasn't even sure that they were still going.
Anyway,
> >this thing always worked in that the amplifier kept producing output, but
> >there was, at the very least, a background 'rustle' and at worst an
> >alarmingly loud crackle, that can't have been doing the internal bass
For simple 2 land devices like Rs and Cs , apply the tweezers across the
long axis or short axis? flat good metal/metal contacts generally shortwise
but full-on solder contact lengthwise although spherical/flat contacts until
initial solder melt.
have you tried cut finger-nail clipping test - oh no a reason to save nail
clippings. Sometimes running a point-ended clipping along the run of PLCC
pins , the "note" will change with poor soldered pins compared to the rest
N_Cook
>
I wonder if there is a "one-time" formulation of solder, low temp initial
use, then higher temp if reworked, or some sort of chemical de-eutectic
process over time.
The earliest PbF i've found was 2001 Yamaha unit
JW
Message id: <iiu1ks$8jl$1...@news.eternal-september.org>:
No I haven't heard *that* one yet. What will people say at work when they
see a dish full of clippings? :) Perhaps a plastic probe of some sort
might also work...
lsmartino
(...)>
> I hate the stuff with a passion >:-(
>
> Arfa
I agree. I just repaired the control card of my room air conditioner.
The PCB was marked as ROHS. The failure was that the swing motor wasn
´t working properly. It would work sometimes, and sometimes not, until
it didn´t turned on no matter what. Testing the motor for continuity
revealed that the internal wiring was ok, so the problem was in the
control card. Testing of the relay which turns on/off the motor showed
nothing relevant, prodding the relay showed nothing too and to the
naked eye the relay looked like it was well soldered to the board
without signs of arcing. Nonetheless I decided to remove the relay and
solder it back... and problem solved :-/
I don´t know for sure what happens to lead free solder joints over
time, but seems to me that over time the solder joint becomes some
sort of insulator, even if it seems OK both physically and
mechanically.
FWIW, a swing motor just consumes 4W at 220 VAC. It´s almost equal in
power and size as a turntable motor for a microwave oven.
N_Cook
>
... And how many times do these lead-free bad
> joint jobs bounce a couple of weeks later ? Can you imagine the
implications
> if the rotten stuff ever does find its way into avionics and other
> life-preserving areas ? New programme on Discovery ? "Aircrash
> Investigation - The Lead-Free Years" ?
>
From an electronics engineer within an exempted industry, noy just allowed
to use leaded solder but contractually must use tradional materials in there
entirety. His company does not automatically believe documentation that
comes with components specified as being non-RoHS. They test whether the
tinning is 100 percent tin or traditional and not rely on
fraudulent/erroneous paperwork. The implication is that other exempted
end-users would not be so stringent