[moved] Partly wet circuit board.

[JustinN]

I'm a complete newb in the area although I have saved a number of people's iPhone logic boards after being submerged in saltwater a few times.

I have a deer feeder we use in the our property to feed the local deer. I went to refeed and do regular maintenance and I noticed the weather protection piece was filled with water (no telling how long). To my suprise the battery connections were a lil bad but after a little tweaking it worked fine. All the buttons worked and i was able to reprogram the timers. I walked out a week later and noticed the timer had gone off. It showed the time on the lcd, but the program button wouldnt work while the + and _ as well as the test button would work. I assume the water level didnt go higher than the program button.

I took it apart and found corrosion on the back of test button. I attempted to clean it with isopropyl along with a toothbrush and I had no results. While being disconnected from the battery the lcd still showerd power but i assume the capacitor just kept holding the charge. I removed the circuit board from the panel order to see if there was corrision on the front. I had to remove the brown board (pins connected to lcd) in order to get a screw out and pull it from the panel. Once i did this the lcd shut off. I cleaned the corosion, placed it back together and i can not get anything to show on the LCD. Much less get the buttons to work like the test feature.

Any Ideas?

Any help would be appreciated.

 

[SLK001]

As a general rule, water and electronics don't mix well. Check to see if the battery has enough voltage to power the unit. Also, the relay may be full of water. Check to see if the switch still works. As a last resort, use a hair dryer and gently warm the PCB to ~150F to help drive off the water.

Rain water is generally fairly pure and pure water is a poor conductor, but ionic contamination could have occurred and made your feeder a pile of used parts.

 

[Relayer]

Hello JustinN,
Make sure the membrane has been re-aligned correctly when you reassembled the unit.
See below:

Regards,
Relayer

 

[JustinN]

I'm not exactly sure why, but my post have not been appearing or has been deleted. Currently, I have the lcd working. It required a lot more pressure than I realized. I've heated up the board and was unsuccesfull the top 3 buttons work but the bottom one does not. what other suggestions are there?

 

[Relayer]

Hello JustinN,
Check the picture below:



(Edit: The arrow on the far right is supposed to be a dark blue, but almost looks violet)
There is a good chance that the corrosion has eaten some of the tracks on the circuit board.
You need to perform a continuity check between the points shown in the picture.
As for the violet (larger) arrow, you need to trace the via indicated to the other side of the PCB.
Follow it along, checking for continuity, as well as trace it to a component/s it will go to. More than likely a pull-up
resistor and possibly to an SMD transistor . You would need to check the resistor to make sure it hasn't gone high or open circuit.
You will also need to check the transistor as well, if there is one.
From what I can see from the photo, it almost looks like the track just below the "Prog" button land has been
eaten away.
If you don't have access to a multi-meter to check for continuity, see if you can borrow one form a friend
or run down to your local electronics shop and ask them to perform the check.
If you do find a track eaten away, it can be repaired using a single strand of wire from a multi-strand wire.
Please let us know how you get on.
Regards,
Relayer

 

[SLK001]

I've looked at your switch contacts and I don't see any significant corrosion. Sometimes the conductive rubber part of the switch will breakdown and become much less conductive. Try shorting the particular switch with a small piece of aluminum foil and see if it will now work. As a last resort, you might have to replace the rubber switches with real push button switches.

 

[Mattylad]

When you have it all working again (consistently) I would suggest a coating of PCB lacquer to protect it more, obviously not on the switch or LCD contacts etc.