Repair Circuit Board tracing?

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redknife

Chris
Corporate Member
I bought the Woods Remote control outlet for the shop. https://www.amazon.com/gp/product/B001Q9EFUK/ref=oh_aui_detailpage_o05_s00?ie=UTF8&psc=1
Used it once and left it in my pants pocket and it went through the washer/dryer.
Now the remote stays on. The off button temporarily turns the remote light off but as soon as you let go it goes on again.
Looking at the PCB for the remote control, there is evidence of trauma to the PCB copper tracing leading to one of the chip pins:
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Kind of weird that there would be a gouge there because the remote case was still intact. The copper is clearly peeled back, though.
Here are broad views for perspective.
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Would an application of solder work to bridge the gap or other suggestion from electronic gurus?

Whole thing cost $11 so this is an exercise in not being wasteful vs futility.
 

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Phil S

Phil Soper
Staff member
Corporate Member
That trace that is open looks like it was scratched open, possibly a manufacturing step required to make it work. Much cheaper to scratch one trace off than redo the entire board. That trace was there to apply ground to one of the chip pins - It would help me if you could get a photo showing the numbers on that chip.

Just a guess here - I am thinking your switches are still wet and conducting some. Try putting it in the sun for a day and see if it does not dry out and start working or option B would be put it in a closed bag of rice for a few days or just order a new one
 

redknife

Chris
Corporate Member
That trace that is open looks like it was scratched open, possibly a manufacturing step required to make it work. Much cheaper to scratch one trace off than redo the entire board. That trace was there to apply ground to one of the chip pins - It would help me if you could get a photo showing the numbers on that chip.
Thanks. I guess it would make more sense as a manufacturing interruption.

Here is the chip (AUT980202-B1 AUT1631):
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I'll try drying it more.
 

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nn4jw

New User
Jim
I agree that the the gouge you see on the circuit board was intentional and has nothing to do with your problem. Both of Phil's suggestions are good. I prefer the rice idea so as not to overheat the chip. I also suggest that you blow off the switches with some compressed air before burying the board in rice without the case. Leave it in there for 4-5 days and then a few more if it still has the problem.

Good luck.
 

ehpoole

Administrator
Ethan
I agree that the the gouge you see on the circuit board was intentional and has nothing to do with your problem. Both of Phil's suggestions are good. I prefer the rice idea so as not to overheat the chip. I also suggest that you blow off the switches with some compressed air before burying the board in rice without the case. Leave it in there for 4-5 days and then a few more if it still has the problem.

Good luck.

Actually, if you have an oven that can be reliably set to somewhere between 150-200F (double check with a thermometer first) then you can go ahead and bake the circuit board for about 8 hours. Spend the first half as close to 150F as you can get, then spend the remainder at something shy of 180-200F (staying just a bit below the boiling point of 212F). This will drive out any remaining water very effectively, though there is a chance that corrosion may have set in if the board was powered at the time it was washed (i.e. battery installed). It is also a good idea to first wash the board with either distilled or deionized water to help remove any remaining salts and surfactants prior to drying.

Very seldom will a temperature below 212F (100C) cause any damage to circuit board components, though higher temperatures than such can damage some plastics used in switches, potentiometers, sensor packages, etc. But most electronics can safely operate with junction temperatures as high as 125C (Celsius), of higher, without any damage whatsoever, so bringing things just below 100C (212F) keeps one well within the safe zone. The reason we wish to stay a bit below the boiling point of 212F/100C is to avoid suddenly flashing off moisture, as we want to to escape gracefully as a vapor, so we begin at a much lower temperature for a number if hours to drive off most moisture, then raise things to 180-200F to finish driving off moisture.

I also concur that the cut trace was intentionally removed during production and not the cause of your fault.
 

Charles Lent

Charley
Corporate Member
If it's turning back on as soon as you release the stop button, the on button is likely stuck on or shorted and there's nothing wrong with the stop button. You could try disconnecting the start button to see if the problem goes away. If it does, a new start button might be all it needs A jumper across the two contacts, touched briefly, could function in place of the start button for testing purposes. If the rest of the circuit then functions properly, a new start button would be all you would need.

Cleaning in distilled water should not hurt it, but the start button might have leaked a little soapy water into it and getting it back out is quite unlikely with any washing process. The soap in the water as well as any minerals will make a conductive path through the switch that will remain even if the water that brought it dries up. Only complete removal of these minerals and soap will restore the function, if this is what is actually causing the problem.

Be certain that it's totally dry before trying to use it. Don't reconnect that land pattern. It was scratched off for a reason, likely a manufacturing change due to an error in the circuit board design..



Charley
 
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ehpoole

Administrator
Ethan
If it's turning back on as soon as you release the stop button, the on button is likely stuck on or shorted and there's nothing wrong with the stop button. You could try disconnecting the start button to see if the problem goes away. If it does, a new start button might be all it needs A jumper across the two contacts, touched briefly, could function in place of the start button for testing purposes. If the rest of the circuit then functions properly, a new start button would be all you would need.

Cleaning in distilled water should not hurt it, but the start button might have leaked a little soapy water into it and getting it back out is quite unlikely with any washing process. The soap in the water as well as any minerals will make a conductive path through the switch that will remain even if the water that brought it dries up. Only complete removal of these minerals and soap will restore the function, if this is what is actually causing the problem.

Be certain that it's totally dry before trying to use it.



Charley

I suspect there is very likely water in the stuck button (they are water resistant but not water tight), which is why a thorough rinse in distilled water and a good gentle bake are worth trying -- both to help clear out the conductive salts and drive moisture out of everything.

However, if you need to replace the button odds are good that I will have a suitable spare if you can give me suitable metric or imperial mils dimensions of the tactile switch -- square package dimensions HxWxL, plus the height of the button above the switch housing, as well as the spacing from the inside of one pair of leads (on the same side) to the outside of the next (or center if lead to center of lead, same thing), which will give the lead pitch value. The dimensions are important as they may be either imperial or metric and the exact height of the push button top is fairly critical if it is to reinstall and function properly in the original housing as the switches come in many height choices.

Good luck regardless. We all have such moments!
 
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