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Water-damaged PCB repair Answered

So water leaked in to the General Electronic Module (GEM) on my pickup and now it's acting all funny. A/C runs when the ignition is off, randomly switching to 4L, airbag light chattering on and off, etc. I want to try and repair it. My intuition is that it just acts up when there's stray conductivity between traces/elements, so if I give it a good clean and keep it dry it should work like new.

However, I noticed upon pulling it apart that there's some corrosion taking place. Can anyone suggest a good way to repair these traces/SMD resistors? I have a soldering iron but heavily oxidized things don't take solder well in my experience. Or should I just put some lacquer on it and not worry about it?




20 days ago

She's currently using a QSC K10 which is excellent , but more and more is being asked to perform in powerless locations.
Looking for some advice on battery powered options. Here's how I see it:
  • buy a new battery powered speaker
  • buy a power station (but how much wattage would I need? And how many amp hours etc for 30mins of playing?)
  • buy an inverter and hook up a couple of car batteries in parallel...
The K10 maxes out at 2000w but I doubt we ever need more than 1/3 of that (~600w) for a ceremony.
I'm thinking 2 X 40ah car batteries would give me 80ah X 12v = 960watthours
If I went down this path and used an inverter could I use a modified sine wave? Or would that buzz / screw with sound ?
I'm pretty tight on cash at the moment so would like a solid option that keeps price down.
Any advice appreciated

4 weeks ago

If it is acting up then you still have moisture left somewhere - or already corroded parts that resulting in failure while trying to use it.
General approach goes like this:
Get destilled or at least demineralised water.
Fill a suitable container with it and submerge your electronics in it.
Move it around to ensure water is really getting into all cavitities.
As it was saltwater repeat this at least twice with fresh water.
The get rid of the water and trapped moisture when done fill a container or bag with methylated spirit and submerge your electronics in it.
Move it around or gently shake it if in a bag.
After 5 to 10 minutes remove and swing it around a bit to drive out drops.
Let sit in a warm place for about an hour so ALL leftover alcohol is evaporated.
Alcohol binds well with water, so it helps to also evaporate the water that is still left in trace amounts.

The corrosion I see in your pics is from short term salt damage and no problem, the pitting you see is salt - this will be gone after cleaning it as above.
A soft brush helps to speed things up in areas you can access with ease.
If all works fine after this then protecting the electronics with some varnish is a double sided solution.
Sure it will help to some extend to prevent future water damage if you drown it again.
But it can also mess with heat distribution.
The added layer acts like a coat and will hinder proper air cooling to some degree.