Left keywell row intermittent issues

[ttttcrngyblflpp]

The left half of my keyboard has intermittent issues where sometimes a row of keys, e.g. the home row, will not work, or pressing a key in a row causes all other keys in the row to be actuated as well. When this happens I usually open up the keyboard and put it back together and then it goes away again...

I've tried following the troubleshooting resources available, which makes me think that this isn't an issue with the PCB, but possibly with the soldering on the keywell itself, probably the ribbon cable port? Any help would be appreciated.

[stapelberg]

I've tried following the troubleshooting resources available,

Can you list what specifically you have tried? Maybe something else comes to mind then.

which makes me think that this isn't an issue with the PCB, but possibly with the soldering on the keywell itself, probably the ribbon cable port? Any help would be appreciated.

Could be anything. Most common are bad solder points. You could just re-solder all connections relevant to the affected keywell.

Less common, but also possible are bad traces on the PCB (caused by wear and tear). In that case, you would need to solder in a cable to bridge the sometimes-broken trace. These are hard to find, though — maybe apply a voltmeter in continuity testing mode and flex the PCB a bit to see if the contact stays or is flaky.

Hope this helps and good luck with finding the issue!

[afonsoguerra]

Just to add my experience. With use and if you take the molex ribbons in and out a few times, they might get bent corners and as such they can go in slightly sideways. This causes some tracks to not connect properly. I suggest you remove the molex ribbons from both sides, clean it a bit, inspect it and re-seat it properly and see if the problem goes away. You can also swap ribbons within the keyboard and see if the problem shifts to a different area of the keyboard. Thankfully, the ribbons themselves are not too hard to source and replace if that is your problem.

[stapelberg]

@afonsoguerra Could you share where you sourced a working ribbon cable? Do you have a link / model name perhaps? Thank you

[afonsoguerra]

I got mine from RS or Digikey, don't remember, but right now I can only find it in stock in digikey.

https://www.digikey.co.uk/en/products/detail/molex/0151680815/4143332

https://tools.molex.com/pdm_docs/sd/151680815_sd.pdf

Specs are: 13 Position FFC, FPC Cable 0.049" (1.25mm) 3.000" (76.20mm)

Note, this is longer than the original and has smaller exposed contacts than the original (CivLux E208903 - AWM 20960 105C 300V VW-1 ), but the molex is working well here.

[stapelberg]

Thanks @afonsoguerra, I added this info to the README :)