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Posted to sci.electronics.repair
Mark
 
Posts: n/a
Default Water damaged Keyfob

Hi,

I wonder if you can make any suggestions on my problem.

I have a high frequency gate opener key fob issued by work.
Unfortunately it was left in a jacket that went in the washing machine
and afterwards the keyfob no longer worked.

I took it apart and cleaned up the circuit board with alcohol (tape
head cleaner) and let it dry for a day. On testing it it didn't work
so I decided to clean it again and through a complete slip of the mind
I put it together and tried it while still wet and it showed signs of
life. I thought the second clean had done the trick. I let it dry and
tried it again but it didn't work. I applied some alcohol to it to wet
it (component side) and it showed signs of life.

Therefore when the board/components are wet it shows signs of life but
nothing when dry. The unit is pretty straight forward, a single
surface mount I, surface mount resistors and a couple of transistors,
a pot, a crystal, one component which I don't recognise and two 3v CR
batteries. The pcb is double sided and a visual check shows all tracks
look complete and ok and not corroded by the water.

I'm an enthusiast who has built circuits before but I don't have in
depth knowledge or test equipment.

Can anyone shed any light on this? Why it works when wet?

Thanks,

Mark.