Leopold FC980C Repair Help

Hello, I’ve had a FC980C for years now that I love, but I accidentally got a few drops of water on it a few days ago. At the time, I didn’t notice that it had happened, and it seeped down onto the PCB, and I noticed that I could no longer press my “enter” key.

I unplugged my keyboard and soaked up a couple of drops of water with a cotton swab, and let it dry, but that enter key still doesn’t work at all. All the other keys are functional and working fine.I’d like to figure out how I can fix it if possible. I cleaned the areas I thought might be affected with isopropyl 91%.

I took a couple of pics. The key is #43.

I’m not great at electronics, but I have a multimeter and I thought that maybe if it’s just the enter key, perhaps it’s some trace that got messed up? Does anyone know how I could go about troubleshooting what is wrong? Also, does anyone know what this white seal is and if it can be taken off without damaging anything?

Any advice on how I could go about fixing this is greatly appreciated. I love this keyboard!

Here is the back side:

are you sure you got the capacitive spring back in it when you tested it? :man_shrugging:

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Yeah, I think I’ve done that and swapped springs and domes with 2-3 other keys multiple times. I’ve been trying to learn how these capacitive sensors work. I’d be down to try to do some continuity tests to try to find if something is shorted or whatever, but I don’t have enough knowledge of what I’m looking at.

oof first off sorry that happened to you.

can’t help on traces/multimeter thing cause i can’t speak to that but 1. don’t try to peel off the white pad or scratch it up–water won’t affect that. probably went into the connector there or something else is happening. like pixel said, reseating the spring is a must. and idk if you’re doing it onto the pcb and laying the dome on top–try putting the dome and spring into the plate and then putting the pcb on top next. that will help ensure that the spring and dome are as centered as possible.

not sure why only the enter key is affected though, can’t really see or tell that anything is off from the front and back view of the key you’ve provided here.

Alright, I won’t mess with the white pad. Do you happen to know what it is though?

Yeah, it’s like you say that I was putting the spring on the PCB, then the dome on top, then laying the plate, but I will try the other way around.

The enter key being the only thing affected is really odd. Also, the enter key being so close to the connector really makes me glad that it is only the enter key messed up. If water did go into the connector, I would expect that more keys would be nonfunctional…but I honestly, don’t know.

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its the silk screen for the pad. i do not recommend modifying or messing with it at all. continue to check the entire board for any leftover water and also check the spring for anything that might be stuck on it, or even inside the dome.

try aligning the other way around and good luck. you can also test for registration by hooking up the whole pcb and daughterboard to power and touching the pad with your bare fingers. it should ** actuate.

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Look at the two traces that goes out of the pad of the enter key and see where they go.
If it goes to a vias then there is a trace on the other side that follows the signal route.

Very often vias are destroyed by spillage and signal is broken. You can check with your multimeter for continuity of the two traces connected by a via (you may need to gently scrap the solder mask to access the copper layer of your traces.


Okay, this morning, I checked the board for more water and didn’t find any. I checked the springs and domes and made sure they were clean. I aligned things in various ways and tried to see if anything would register. I tried to just put my finger on the sensor to see if it registered at all, and none of these options worked.

I tried to follow the trace and test those vias to see if any were broken, but they were so tiny, I couldn’t get anything to register. Even the smallest gauge wire I have can’t seem to go through the via, so I may have to do what Rico said and scrape off just a bit of the solder mask. I’ll try to do that when I get some time.

I found some notes about the board here, but I’m still not 100% understanding how the row and column designations work. I thought maybe if I could understand it, I could see if capacitance was being measured for the enter key.

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