Electronics > Beginners
Inverter as a boat anchor?
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jerryk:
I have a friend that keeps having inverter mishaps, the spoils of which he passes to me. The photos show the latest disaster.  It was new last year but got exposed to salt water while it was on.  A major part of the damage is in the photos below.  Boards are again covered in conformal coating to make repair prospects more distant.  I think this thing is just toast but may practice on dealing first with corrosion then strip the conformal coating on some of the boards and see if how far I am willing to go.

Beyond that I may salvage some of the parts.  Is the transformer any good given the extent of the corrosion?  Is there anyone that sees this as repairable given the proper level of skills?

Jerry
james_s:
That doesn't look too bad, I've certainly repaired stuff that was in worse shape. Desolder the affected parts and scrape the coating off with a piece of stiff plastic or use a brass brush in a rotary tool. Do the initial desoldering outside or with some decent ventilation since the coating will probably stink.
Zero999:
If it wasn't for the conformal coating, it would be a lot worse. After you've done the repair, I'd recommend covering it with a layer of conformal coating, which is necessary as it's clearly used in an application were it might get wet.
jerryk:
I am making some progress and feeling a little more optimistic about the prospect of this turning into a repair.  The FET's were difficult to remove but I did manage to remove the damaged row of them and got things cleaned up.  So far the rest of the inverter board tests out ok as far I can tell.

Next question is what to do with the rusty transformers.  This is salt exposure so it seems to have had a real impact to the cores of these guys.  I also can see in the main transformer signs of salt/corrosion residue in the outer windings under the outer tape layer.  Not much but enough that I don't want to leave it.  I'm not sure if I might chase the salt further into the windings or if I should even worry about it.  Should I try to wash the transformers in distilled water followed by IPA soak?  Can I take the wire brush wheel on my bench grinder to the rust on the outside and then revarnish?

I've attached some photos of the rust I'm up against and the progress made on the inverter board and the mcu after cleaning.

Thanks for the help.

Jerry
james_s:
Rinse out the salt with clean water, let it dry thoroughly, varnish if desired. The cores you can either leave alone or you can wire brush them and coat with paint or varnish but the rust on the iron is cosmetic and won't affect operation.
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