[help] Keyboard keeps disconnecting and reconnecting...

[futurecrime]

I asked this in another thread but will try a dedicated thread here.

My Matrix Abel keeps disconnecting for a few seconds then reconnecting.  It only does it when I'm typing, never when I'm not using the keyboard (I know because it makes a sound in Windows when it does it).  It'll stall for a split second then punch in a string of whatever character was the last key I pressed eg. eeeeeeeeeeeeeeee   then it'll reconnect after a couple of seconds and work fine.

I've tried different USB cables and USB ports to no avail. I'm using Windows 10 but I tried the keyboard on Mac and seem to have the same problem...

Also, maybe unrelated but the key between right windows key and right control doesn't register. I assumed this was AltGr so it won't register on something like keyboardtester.com, but it doesn't seem to work with any keys to give me alternative characters, and it doesn't seem to work as Fn either. It just does nothing as far as I can tell. Is there a way for me to test if it's working at all?  I'm using the English (United Kingdom) setting in Windows 10.

Any help troubleshooting all this would be greatly appreciated.

[invariance]

Connection issues: different usb cables, different machines with different OS's - I am thinking there could be a physical problem with the keyboard.  More specifically a dry joint maybe around the microcontroller/usb socket (worst case a hairline crack in the pcb).  It could be something as simple as the usb socket is mounted .2mm too far back and the usb cable is making a poor connection.

I'd start by removing it from the case and seeing what happens.  Try wiggling the usb plug up/down, flex the pcb in various directions gently, freeze spray the smd ic's, things like that.  Even hold the pcb up to a very strong light to look for a crack (unless it is too dark and thick).


The AltGr key: use a multimeter to test for continuity when the switch is pressed.  Don't place the test probes on the switch itself, but on some other points on the pcb where the tracks run off to.

See how you go.

[futurecrime]

Connection issues: different usb cables, different machines with different OS's - I am thinking there could be a physical problem with the keyboard.  More specifically a dry joint maybe around the microcontroller/usb socket (worst case a hairline crack in the pcb).  It could be something as simple as the usb socket is mounted .2mm too far back and the usb cable is making a poor connection.

I'd start by removing it from the case and seeing what happens.  Try wiggling the usb plug up/down, flex the pcb in various directions gently, freeze spray the smd ic's, things like that.  Even hold the pcb up to a very strong light to look for a crack (unless it is too dark and thick).


The AltGr key: use a multimeter to test for continuity when the switch is pressed.  Don't place the test probes on the switch itself, but on some other points on the pcb where the tracks run off to.

See how you go.

Thanks for the help.  I opened it up last night and went over all my soldering with a magnifying glass, noticed some joints that could maaaaaybe be causing a problem.  I plan on resoldering them tonight and seeing if that solves it. And I'll check according to your recommendations as well.  Cheers.

re: AltGr, I actually just ordered a multimeter today (I'm a real noob obviously!) so will be able to check soon enough. Thanks!

[futurecrime]

I resoldered a bunch of joints last night but to no avail.  I managed at one point to type on it for an extended period to the extent that I thought it was fixed, then I put it back in the case and it went back to how it was before. However it didn't always work fine out of the case so it's not the case per se.  Jiggling the cable around in the socket never causes it to disconnect, only typing makes it disconnect... Can't see any cracks in the PCB... ugh, this is becoming really bothersome. Will sit down with it again tonight and see if I can get any further. Will try the freeze spray trick, and hopefully my multimeter will arrive today as well so perhaps I can put that to good use...

Still open to suggestions!

[futurecrime]

Spent all evening ****ing around with this. Managed to get it to a point where I typed on it for about half an hour non-stop without a problem, then moved the keyboard and the problem came back.  I'm pretty sure it's related to the mini-usb port now, although it still only disconnects when typing... so I dunno... I've tried squeezing it slightly with some pliers to tighten it up, made it worse, made it better, but I can't get to a permanent, reliable fix. I don't know if it's just a case of needing to replace the port or something... I'm past my skillset now, this was my first build, first time soldering... totally new ground to me, but I'm pretty convinced it's not something that I've messed up.

It's been edifying trying to troubleshoot it but I don't know how much more time I can really dedicate to it. Looks like my best option is to bite the bullet and get a replacement PCB from TaoBao while they're still available. I guess if I've got a replacement there then I can be more bold in my attempts to fix this one as it won't matter if I bork it completely.  Learning is fun! And expensive!

[invariance]

Another pcb is probably the best bet.

Something else I would try is to open up the Device Manager in windows and see if you get device drop/reconnects in either the "Human Interface Devices", "Keyboards" or the "Universal Serial Bus controllers" lists as the board drops out and in.
It seems weird to be repeating the last character pressed as you mentioned in your OP, as software won't keep putting in characters when there is nothing and the keyboard shouldn't be outputting characters when it loses connection.  Starting to make me wonder if it's more than just a bad usb port.

I don't know how much this would help but maybe have a window open with hidlisten.exe running as well as the Device Manager and when you hear the Windows sound quickly check each window for suspect behavior.  Hidlisten will look like a heap of rubbish as it is the scan codes, but it may help with cross checking: no keyboard it outputs ......., repeated characters will have repeated scan codes.

Good luck.

[futurecrime]

Thanks again for the advice. I've ordered another PCB from TaoBao (luckily there was a UK TaoBao GB finishing yesterday) so I feel some relief that this board will be OK at some point.  I think I'll take a little break from attempting to fix it as is (it's sunny in the UK right now!), but will have another bash at it soon enough and take your extra tips on board. Cheers!