Author Topic: [Help] QWERTY Row Not Working on Keyboard After Desoldering  (Read 297 times)

0 Members and 1 Guest are viewing this topic.

Offline Blurify

  • Thread Starter
  • Posts: 6
[Help] QWERTY Row Not Working on Keyboard After Desoldering
« on: Sat, 19 June 2021, 17:07:56 »
Hi, I wanted to change the switches on a Durgod K320, but discovered that the entire QWERTY row (from Tab to PgDn) does not register while I was testing the desoldered PCB. This was my first time desoldering, and I know that I have lifted multiple pads. I'm hoping that there is still some way for me to fix this row, otherwise the keyboard would have very limited use.

Additionally, some other keys did not work, but I believe that I have fixed them with switch bridges. Also, the entire FN row also does not work and I believe that it is due to some lifted pads as well as a detached copper trace on the other side of the PCB. This row is not as important as the one in question, but I would like to fix this row as well if it is possible.   

Pictures: https://imgur.com/a/ZR0OGLz

Offline suicidal_orange

  • * Global Moderator
  • Posts: 4323
  • Location: England
Re: [Help] QWERTY Row Not Working on Keyboard After Desoldering
« Reply #1 on: Sat, 19 June 2021, 17:23:06 »
Definitely a lot of lifted pads, and two of them being the important ones where the rows link to the controller chip.  Sadly it's a black PCB so it's very hard to see what's going on, but the controller chip is above the arrows so and there are no traces running vertical on the front of the board so they must be on the back.  Can you make out a trace heading down from the lower/right pin of a switch on the back, or can you take a pic where the light highlights the traces in that area?

As long as all the damage is at the switch end of the traces it's quite easy to fix, assuming the traces aren't close to others the whole way.
120/100g linear Zealio R1  
GMK Hyperfuse
'Split everything' perfection  
MX Clear
SA Hack'd by Geeks     
EasyAVR mod

Offline Blurify

  • Thread Starter
  • Posts: 6
Re: [Help] QWERTY Row Not Working on Keyboard After Desoldering
« Reply #2 on: Sat, 19 June 2021, 18:31:16 »
Thanks for the quick response, here's some pictures of the traces: https://imgur.com/a/p5roS6F

Offline suicidal_orange

  • * Global Moderator
  • Posts: 4323
  • Location: England
Re: [Help] QWERTY Row Not Working on Keyboard After Desoldering
« Reply #3 on: Sun, 20 June 2021, 07:03:41 »
That's the right kind of picture but they don't show the switches above the arrows where the damaged traces start or the controller chip where they end.  Please try again :)
120/100g linear Zealio R1  
GMK Hyperfuse
'Split everything' perfection  
MX Clear
SA Hack'd by Geeks     
EasyAVR mod

Offline Blurify

  • Thread Starter
  • Posts: 6
Re: [Help] QWERTY Row Not Working on Keyboard After Desoldering
« Reply #4 on: Sun, 20 June 2021, 14:16:41 »
Sorry about that, I just updated the pictures in the link

Offline suicidal_orange

  • * Global Moderator
  • Posts: 4323
  • Location: England
Re: [Help] QWERTY Row Not Working on Keyboard After Desoldering
« Reply #5 on: Sun, 20 June 2021, 16:31:20 »
Did I mention how much I hate black PCBs?  I really do >:D  I still can't see anything helpful beyond saying it doesn't look like the QWERTY row connects from the DEL END or PGDN switches where it would make sense to put the connections.  But it's a commercial PCB so that's not really surprising.

Lets try another angle - can you read the text on the controller chip and post it?  Maybe a datasheet will show which pins the switches could be connected to, then you can do some poke testing to find out which has been disconnected.
120/100g linear Zealio R1  
GMK Hyperfuse
'Split everything' perfection  
MX Clear
SA Hack'd by Geeks     
EasyAVR mod

Offline Blurify

  • Thread Starter
  • Posts: 6
Re: [Help] QWERTY Row Not Working on Keyboard After Desoldering
« Reply #6 on: Sun, 20 June 2021, 21:04:11 »
The text on the controller chip is: ARM STM32F070. Here's a picture of the chip: https://imgur.com/a/w0WtHYo

Offline Blurify

  • Thread Starter
  • Posts: 6
Re: [Help] QWERTY Row Not Working on Keyboard After Desoldering
« Reply #7 on: Tue, 22 June 2021, 21:01:27 »
I'm not sure if this is useful, but I was trying to find ways to activate a keypress on the QWERTY row and was not able to do so no matter what I tried. I found that whenever I bridge a working switch with one of the switches on the QWERTY row, the remaining switches on this row to the right of the bridged switch would activate keypresses for another row.

Offline suicidal_orange

  • * Global Moderator
  • Posts: 4323
  • Location: England
Re: [Help] QWERTY Row Not Working on Keyboard After Desoldering
« Reply #8 on: Tue, 22 June 2021, 23:25:52 »
Sadly that doesn't help, it's standard.  Each 'column' is set live then depending which row returns the signal it knows which key connects the two.  It's the trace from the dead row back to the chip that's broken, your bridge connects the two rows so it gets confused.  If you can see a trace heading other than straight across the lower pins of the dead row that's the one.  Not easy on a black PCB.

Life is very much in the way, I'll have a look for the chip in ... 11 hours when I get home and hopefully it's standard and they didn't invent their own model number to write on it.
120/100g linear Zealio R1  
GMK Hyperfuse
'Split everything' perfection  
MX Clear
SA Hack'd by Geeks     
EasyAVR mod

Offline Blurify

  • Thread Starter
  • Posts: 6
Re: [Help] QWERTY Row Not Working on Keyboard After Desoldering
« Reply #9 on: Tue, 22 June 2021, 23:31:44 »
No worries, I appreciate your help. In the meantime, I'll look for the trace you mentioned.

Offline suicidal_orange

  • * Global Moderator
  • Posts: 4323
  • Location: England
Re: [Help] QWERTY Row Not Working on Keyboard After Desoldering
« Reply #10 on: Wed, 23 June 2021, 12:43:54 »
Two dots and one cut corner - helpful.  I found the pinout on page 24 here but without knowing which corner pin 1 is in that's not much help.  Hopefully you can find the trace!
120/100g linear Zealio R1  
GMK Hyperfuse
'Split everything' perfection  
MX Clear
SA Hack'd by Geeks     
EasyAVR mod