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geekhack Community => Keyboards => Topic started by: mirzar on Sat, 06 June 2020, 20:31:55
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Hi! I was setting up my KBD67 MKII Hotswap PCB when one of the Kailh sockets fell off.
The issue is that now all the Switches that are on the right of switches are also not working. See images: https://imgur.com/a/llL4qaY (https://imgur.com/a/llL4qaY).
I don't mind if the actual switch that fell off does not work but really want the other switches to work - I tried checking the connection with the tweezers and nothing.
I found this https://www.youtube.com/watch?v=ndObpHGsY6E (https://www.youtube.com/watch?v=ndObpHGsY6E) on the KBDFans website but it does not seem to explain what is being done.
I have access to a soldering iron and have soldered a bunch before.
Any idea on how to fix this with instructions?
Should I remove the pads entirely before trying to resolder and what kind of wires do I need to connect them to the rest of the row?
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Yikes, the solder pads pulled out and everything. You might have to scratch the soldermask and directly solder something there.
There is likely a row or column wired in series, and the removal of the switch might have disconnected this. You will have to find the physical point where the connection isn't being made, and use a jumper wire to bridge it.
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Ouch, so much for a 'solderless' board!
Luckily it's pretty standard so find any wire (at the voltage and current of a keyboard even really thin magnet wire will be fine, preferably stranded not 'stays where you put it' solid type as it's easier) and solder the same coloured dots. Yes, I added a fake switch template as space is miles away but you get the idea.
What this does is reconnect one switch pin to it's diode and on the other side the trace connecting the whole row was routed through the now missing pad so you need to reconnect it in both directions. Not sure how you're going to get the socket to stay put though - hot glue works for jumper wires so maybe try that? In the video they use two part epoxy which is a very permanent solution.
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This is one of a few reports I've been seeing about hot swaps (one respected brand has had a string of them), it seems if the pins are not aligned just right you can push it right off the board. These sockets appear to need something behind the socket to add support. Expect aluminum cases with hot swap to get a lot more expensive.
As for the problem here,
The traces are running through the pad, this was considered bad practice with solder switches but is going to be an even bigger problem with hot swaps. Basically, when the pad ripped off it also damaged the trace killing everything behind it. One can be hooked right to the diode right next to it, the other is probably to the left, but a you will need a voltmeter to verify it.