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geekhack Community => Keyboards => Topic started by: sbunschu2 on Sat, 05 February 2022, 13:54:32

Title: CU80 lifted pads: How to fix?
Post by: sbunschu2 on Sat, 05 February 2022, 13:54:32

Hi everyone,

I recently got the CU80 but unfortunately a few of the hotswap pads lifted off when I put in the switches. From what I've read so far, this means I have to bridge some connections on the PCB.

Based on the attached picture, I did the following:

 1. Green: switch on the right works fine

 2. dark blue: switch does not trigger

 3. yellow: when I short these pads with tweezers, the green switch triggers.

 4. light blue: Tried soldering a small wire between these pads but it does not work. also, bridging with tweezers rarely triggers the key at all for some reason.

Any help on how to fix this would be appreciated...

Title: Re: CU80 lifted pads: How to fix?
Post by: suicidal_orange on Sat, 05 February 2022, 16:47:00

Welcome to geekhack, sorry it's not under happier circumstances.

You can see the diodes connecting along the rows so you need to remove your wire between the two switches - it is causing strange things to happen.

I'm not sure which pads are lifted as they all look good but on each switch the right pad needs to connect to the bottom of the diode (see pink lines) and the left pad needs to connect to the left pad of a switch below, so between the green stars.  I can't see the column traces so it could be either of them - tweezers to the right/pink pad will confirm which :)

[attachimg=1]

Title: Re: CU80 lifted pads: How to fix?
Post by: sbunschu2 on Sun, 06 February 2022, 04:57:58

Hi suicidal_orange, thank you so much for your help!

I tested the correct position on the row below the lifted pad by connecting it with tweezers and pressing the "broken" switch.
Once I had the correct keypress, I just soldered a wire between these pads. Soldering looks quite messy but it works and I am happy  ;D

Screenshot is attached in case anyone runs into the same problem.