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Boom Diggity 6th February 2012 07:56 PM

Water Damaged PCB ?
 
2 Attachment(s)
Hello,
I have 2 orion GX amplifiers that I would like to try and repair. Before I begin, I would like to know if these PCB's are even worth repair. I've never seen the copper traces bubbled up as they are on both of these amps. The first pic shows the bubbling. If they are repairable, the second pic shows a missing diode on the 280 GX. I believe it is for reverse polarity protection. It was burned beyond recognition. I am not sure how to size this diode, for replacement.

zxgravediggerxz 6th February 2012 08:56 PM

Man, that bubbled copper does NOT look good.

Those bubbled traces are lifted off the substrate by the looks of it, I would not recommand you trying to fix it. The traces are being held in place by the conformal coating that is over them and you can probably peel off those traces if you make a small incesion somewhere and just pulled. Than if you try to fix it and remove components you will probably lift the pads.

Who knows, there also might be moisture or water underneath those traces.

I would say that this board is gone sadly, I would say junk it. It will be too dangerous to power up.

Replacing components without a schematic or reference (previous diode used) is very hard unless you can trace the circuits and connections, and figure out what goes trough the diode... even then you might not be able to figure out what it is. Best to find a picture of the internals, maybe online.

It is really crazy to see this. How did this happen? Did you soak the boards in water?

firechief 6th February 2012 09:05 PM

Are you sure that is water? I have seen boards with solder re-flow problems that looked like that.. It may be usable. Try pulling up a trace. Chose one that will be easy to repair.

c2cthomas 6th February 2012 09:10 PM

Here is a link to some photo's that might be of some help. I'm looking around for more stuff too.
Old-school n rare ORION 280GX dual mono (build to meet military quality standard)....

Usually PWB's that have become delaminated will also show damage near the edge of the traces and pads. A quick poke with a sharp probe or soldering iron will show you quickly if the runs are delaminated or have solder waves on them - sometimes extra solder is applied to provide for extra current carrying capacity and sometimes it is caused by a flaky wave solder machine. If the PWB had become delaminated due to water exposure I would expect to see more corrosion present on the component leads as well as some swelling of the fiberglass material the board is made from.

If the tracks have become delaminated there are ways to repair them - but it a VERY time consuming process!!! From the photo's I think you have excess solder and you need to check that out before proceeding any farther.

Good luck with this project - those were good amps back in the day.

grimberg 6th February 2012 11:29 PM

I think the heat inside the amplifier softened the varnish which detached from the copper and sagged. After it cooled down the stretched varnish hardened again, keeping the bubbles.
If my theory is correct, you should be able to poke through one of those bubbles.

kevinkr 7th February 2012 12:16 AM

I think what you might find is solder underneath the solder mask. I have seen something like this before - sometimes it is even deliberate in order to increase current carrying capacity of the traces. (One of my former employers used this technique) Looks like hell, but works fine. I think this pcb may also have a thin conformal coat applied which may be a bigger problem.

Enzo 7th February 2012 12:31 AM

I agree, that just looks like excess solder on the copper under the solder mask.

After wave soldering, many boards are run through what amounts to a dishwasher to clean off the residues. Water hurts boards when they are powered, but for the most part, won;t damage the board.

marce 7th February 2012 02:01 PM

I cocur wit the last two comments, in the old days PCBs had tin lead over the copper and under the resist, this would bubble during wave soldering causing fun when PCB's had to fit in card guides.

Boom Diggity 7th February 2012 06:22 PM

Thanks everyone for the posts. I myself have never seen this before. Albeit, I haven't dabled in repair as of yet. I'll poke around. I got both of these dead amps from a friend of a friend, no telling what happened. I assume they might have been a boat, in a bad installation. Don't want to invest time and money for nothing. I've got others I can tinker with after poking around the traces. Looks bad to me.


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