DAS keyboard intermittent with D and C keys

[sententia]

Hey Everyone,

So I have a Das Keyboard with browns, one of the things which is driving me insane is the D and C keys are intermittent with response. Not always, but now and then they will just stop working for 10 or less strokes. What I've done is swapped the two other less frequently used brown switches from the same board and replaced the D and C ones. However today, it started playing up again after a month of nothing, so you can imagine I thought I fixed it. Today I opened it up again and swapped over the PCB board with another Das Keyboard I have, however this is one with blue switches. The PCB is a daughter board PCB 1.5. However on the blues the PCB was 229, and on the browns - the faulty one - it was 224. At first I thought this would fix it however still happens now and then. It is only the D and C keys nothing else.

I have plugged it in via USB, and it is directly plugged in through a loading dock for my Macbook air. I do have a USB hub coming off it with a few peripherals (printer, mobile, backup hard drive, etc.) but I don't know what to look at it. I use keyrmap for mac to re-map the keys for mac setup.

I have another Das brown at work and nothing is wrong with it, works fine, and it is roughly the same setup. Can anyone shed some light on what I can look into. Would there be something wrong with the board, the software what, and how do I got about fixing it.

[Muirium]

A bit of a head scratcher, this. You replaced switches, but it returned after an extended time. And you swapped the controller, to no avail. The only remaining commonality is the PCB. Something is iffy down there.

Take a good close look at where these switches mount, the trails they touch, and the bit where the controller hooks up to them. Definitely test continuity. The less consistent the problem, the harder it will be to pinpoint, of course.

[Grendel]

C & D probably are on the same matrix column and there is a problem in the trace that leads to C, then D (or vice versa.) Could be a bad solder joint of a bridge wire or a hairline fracture in the traces leading to C/D.

[sententia]

Hey Guys,

Yep, Grendel, discovered that last night. The E key solder and track for D and C was a bit sketchy. I got out a little microscope thing I have and leading towards E saw there was a fracture in the track. I scrapped away some of substrate (green material) and created a bridge for the fracture with some solder. I then got out my multimeter and tested it all the way back to the ribbon. Then tested the switches actuation at the ribbon and it was working fine also. I think it must of been minute fracture and led it to be temperamental. When I replaced the switches it could of been the movement of the board and what have you when working on it that is why I got a month out of it before it started playing up again. I'm pretty sure it is fixed now.

Thanks both, Muirum and Grendel for your help.

Cheeers,