Date: Sun, 27 Feb 2011 16:56:45 -0500
Reply-To: David Beierl <dbeierl@ATTGLOBAL.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: David Beierl <dbeierl@ATTGLOBAL.NET>
Subject: Re: Spare ECU
In-Reply-To: <BFD6D765B863461B93F62C26423550B7@customerPC>
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At 03:51 PM 2/27/2011, HotelWestfalia wrote:
>Yup, you were telling about this before, to fix them under
>magnifying glass. I'm just not sure how I find the crack if it's not visible.
>Is the soldering not holding the leg of the item or it is not
>holding on the board or it's just cracked in half? If your info is
>well conveyed, we might be confident enough to fix it.
Look at these, read the captions...
https://picasaweb.google.com/dbeierl/SolderFatigue#
Every one of those joints except the last one has failed and will
continue to deteriorate internally. Not one is visible to the naked
eye and *at least to my 60-y/o eyes* not under a 10x microscope (much
stronger than a 10x hand lens which is equivalent to a ~3x
microscope). *Probably* none of them is actively causing a problem
right now, but if you have a hundred or so on a board the odds start
to mount up.
Really gross failures can be seen by eye, and if bad enough you can
see the lead move when you push gently on the component. But a joint
can fail electrically without such evident signs. Depending on the
circuit, the joint failure could cause an attached transistor to fail
from voltage spikes.
What makes things harder is that I'd be ashamed to say that I ran the
wave-solder line for the 2.1l ECUs, especially the Bosch ones; or for
the Bosch 1.9l ones. The couple of T-A 1.9l ECUs I've looked at have
had excellent initial solder and much better mechanical design than
the Bosch. Millee's Sally ('85 with T-A) had gross fatigue on every
pin of the external connector but none at all anywhere else. My '84
Bosch ECU had several function-affecting solder failures while I had
it, and repairing them was difficult because the component leads were
oxidized and would not accept solder.
Working on the Westy LED panel would be easy for a beginner. The
temp gauge, not bad. The ECU - my general take on that is that if
you have to ask how then you should probably stay away from it.
As far as I can see this is analogous to computers, i.e. very
expensive. You can pay someone else lots of money or you can pay the
universe lots of sweat/practice/time and maybe seventy five or a
hundred bucks for soldering gear and supplies. Someone with some
money to invest could set up a service to run these boards back
through a wave soldering line. That would be a good answer, but a)
not foolproof and b) you wouldn't like what it would cost,
either. There'd be a fair amount of hand work involved still. The
022D boards also have surface-mount components on the solder side of
the board so they'd need a lot more hand work and component replacement.
Most (all?) of the ten or so ECUs I've studied that I didn't
personally remove from a vehicle had been repaired at some previous
time. The new clean solder is obvious compared to the nasty looking
poor quality wave solder. However these were functional repairs of
maybe five or ten joints at most - under the microscope I found a
hundred or so in each that had failed but might or might not yet be
causing problems. One of those dropped out for an instant every time
the rear wheels went over a sharp bump (that was the OE one in my
'89, and I found and reflowed 125 or so joints. One has been in
service for many months with no problem. One was placed in service,
worked for a week and failed with bizarre symptoms.
I have not seen any board cracks or foil cracks in any ECU I've looked at.
A class-action suit against Bosch or VW probably would be a waste of
time. But I think that if these ECUs had been mounted with internal
or external vibration-absorbing mounts we wouldn't be seeing these
problems. Thermal cycling is an issue, but I think vibration is the
killer here. Filling the case with an insulating gel would have done
it too, I think. And the harness connection is much too stiff and
has too much leverage; and of course it's gotten a great deal stiffer
as the vinyl jacket has hardened over the years.
:(
d
