Author Topic: Please Help! Trying to fix Keyboard PCB  (Read 7060 times)

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Offline Draxion

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Please Help! Trying to fix Keyboard PCB
« on: Mon, 15 July 2019, 21:00:42 »
So basically I took apart my ducky one 2 to lube my switches. I expected something to go wrong as it's my first time doing this. I've lubed a soldering all the switches back onto the keyboard however as expected some don't work. I've fixed some that didn't work using a bridge, however these http://prntscr.com/ofjhpq, 6,7, Y, U, H, J, N and M don't work and I can't find which connections to bridge. Help and input would be great, Thanks for the help in advance!
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« Last Edit: Tue, 16 July 2019, 19:28:01 by Draxion »

Offline ErgoMacros

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Re: Please Help! Trying to fix Keyboard PCB
« Reply #1 on: Tue, 16 July 2019, 01:22:18 »
Hi, Have you tried "6" and "7"?
Looks like you have 2 entire "columns" that are not working. Usually this is a bad connection from the controller to that column.
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Offline Draxion

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Re: Please Help! Trying to fix Keyboard PCB
« Reply #2 on: Tue, 16 July 2019, 08:27:58 »
Yeah, I've already tried that unfortunately. When I bridge one of the keys to any other working keys they fire something, but just never anything in those two Columns. :(
« Last Edit: Tue, 16 July 2019, 19:24:45 by Draxion »

Offline swedishpiehole

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Re: Please Help! Trying to fix Keyboard PCB
« Reply #3 on: Tue, 16 July 2019, 12:27:26 »
This would be a lot easier for you if you had a multimeter to check the diodes and continuity. It can be really tricky to find where to make a bridge and a multimeter really helps.

Offline Draxion

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Re: Please Help! Trying to fix Keyboard PCB
« Reply #4 on: Tue, 16 July 2019, 16:03:35 »
This would be a lot easier for you if you had a multimeter to check the diodes and continuity. It can be really tricky to find where to make a bridge and a multimeter really helps.


I should have one in the garage... So I'd just check which diodes in those two columns don't have current across them? Which would be the ones that need a bridge?
« Last Edit: Tue, 16 July 2019, 16:08:52 by Draxion »

Offline swedishpiehole

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Re: Please Help! Trying to fix Keyboard PCB
« Reply #5 on: Wed, 17 July 2019, 11:07:42 »
Since entire columns of keys don't work, it might just be one diode or solder pad that is causing the problem. If you inspect each solder pad (the metal ring around the hole where the pin comes through) you might be able to find which one got damaged or lifted. Same does for diodes, test each one to make sure they are all working. If that doesn't turn up the source of the problem, you could try what I did: test for continuity between each switch and its diode. The diodes should be marked with a D followed by the number that corresponds to the key position (usually starting with a K, probably on the other side of the PCB). Try each end of the diode with each pin of the switch until your multimeter reports continuity. Then do this for each switch/diode until you find where the break is. PCBs can be complex. When I had a lifted solder pad, I ended up having to make a bridge a few keys away to fix it.

Offline Draxion

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Re: Please Help! Trying to fix Keyboard PCB
« Reply #6 on: Wed, 17 July 2019, 11:39:39 »
Since entire columns of keys don't work, it might just be one diode or solder pad that is causing the problem. If you inspect each solder pad (the metal ring around the hole where the pin comes through) you might be able to find which one got damaged or lifted. Same does for diodes, test each one to make sure they are all working. If that doesn't turn up the source of the problem, you could try what I did: test for continuity between each switch and its diode. The diodes should be marked with a D followed by the number that corresponds to the key position (usually starting with a K, probably on the other side of the PCB). Try each end of the diode with each pin of the switch until your multimeter reports continuity. Then do this for each switch/diode until you find where the break is. PCBs can be complex. When I had a lifted solder pad, I ended up having to make a bridge a few keys away to fix it.

There is definitely 1 of those with lifted pad that's for sure maybe 2. That's why I've been trying to make bridge, but haven't been able to find where to bridge it. I will try testing for continuity and the diodes when I get home for work. Thanks a lot for the input.
Added picture of the PCB where the switches aren't working
« Last Edit: Wed, 17 July 2019, 20:31:19 by Draxion »

Offline Shot4213

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Re: Please Help! Trying to fix Keyboard PCB
« Reply #7 on: Tue, 12 January 2021, 12:18:24 »
Hey draxion, did you ever figure something out?

Offline topopo jr

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Re: Please Help! Trying to fix Keyboard PCB
« Reply #8 on: Thu, 13 May 2021, 12:35:57 »
Sorry for bumping this, but please can I get to know if you fixed it, and if you did fix it, how did you do it? I'm having the same problem right now. Thanks.

Offline suicidal_orange

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Re: Please Help! Trying to fix Keyboard PCB
« Reply #9 on: Thu, 13 May 2021, 13:45:30 »
Sorry for bumping this, but please can I get to know if you fixed it, and if you did fix it, how did you do it? I'm having the same problem right now. Thanks.

Every board is slightly different, post a pic of the area around your problem and we'll work it out.
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Offline topopo jr

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Re: Please Help! Trying to fix Keyboard PCB
« Reply #10 on: Thu, 13 May 2021, 19:57:05 »
Every board is slightly different, post a pic of the area around your problem and we'll work it out.

Of course, sorry for the late reply, but here are some photos fo the keyboard, it's a ducky shine 6, there is only damage in that area in the h and j switches, but you can see marked with sharpie the switches that don't work, in the second photo I tried making a bridge between them, and also connecting the diodes you see there, because that made the keys a, d, g work. I also tested for continuity with a multimeter and everything seems to be connected
I don't know what else can be the problem, if I bridge the h key to the g key, it registers as if the f key is always pressed, and even if I change rows, it goes registers most of the time the f, s, or caps lock key.
Thanks for your time.

Offline suicidal_orange

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Re: Please Help! Trying to fix Keyboard PCB
« Reply #11 on: Sat, 15 May 2021, 02:56:13 »
No problem, I looked yesterday but didn't manage to post anything as my brain is useless at the moment and this is a Ducky so not necessarily sane and consistent.

What I can say is the pattern of every other switch in the Caps A D G suggests it has U shaped 'columns'.  That means the diodes connect alternating as with your cyan bridge.  I guess that bridge has continuity to the cyan dots and the blue ones are also connected.  The 'column' pins are visibly connected across each row so I think all the yellow dots should also have continuity.  If the top pair and bottom pair are connected you need to bridge one of them to the broken ones in the middle - just one bridge, wherever is easier.

Also it looks like the connection to D28 is broken so a short bridge might be needed there (green line)

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Offline topopo jr

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Re: Please Help! Trying to fix Keyboard PCB
« Reply #12 on: Sat, 15 May 2021, 16:31:11 »
Yes, all horizontal switches have continuity, and I bridged the yellow line you drew there, the only thing is, you said only one bridge, that means I only have to connect one of those purple lines? Or one to each switch?

Also the green line appears broken but I checked with the multimeter and it is connected.

Offline suicidal_orange

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Re: Please Help! Trying to fix Keyboard PCB
« Reply #13 on: Sat, 15 May 2021, 17:19:42 »
Yes, any one of those purple lines should fix it.  You've already connected the yellow line to the other switch.
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Offline topopo jr

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Re: Please Help! Trying to fix Keyboard PCB
« Reply #14 on: Sat, 15 May 2021, 18:14:30 »
I tried with only one first, didn't work, attached the second one, and same result, then tried with some alligator clips to link them to 6 and 7 and also the ones under them and don't register at all. But they do work, I bridge them to other keys and register those keys that are being bridged to, but those two colums remain unresponsive between them.

EDIT: Sorry if I didn't post this earlier, but I removed the swithces to change them because they seemed too beaten up and I found this in the right switch, I don't know if the copper has something to do with all of this. (The bridge photos were all taken after I put new ones in)
« Last Edit: Sat, 15 May 2021, 18:26:56 by topopo jr »

Offline suicidal_orange

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Re: Please Help! Trying to fix Keyboard PCB
« Reply #15 on: Sat, 15 May 2021, 20:13:18 »
That copper is weird, looks like you aren't the first person to take this board apart.  I thought you said the rest of the column started working but reading again you didn't - sorry for being stupid.  The chip is on the row with the damaged pads so that must be where the column links back to the controller chip.

If you remove that copper you will probably see a trace heading off to the right, some of the red mask has probably been scratched off and the copper was pressed against it to make the connection.  You can't solder it as it would raise the switch up but you can use the multimeter to see where on the chip the trace connects to.  Unplug the USB before doing this, otherwise you could short the controller pins and kill them.  It will probably be one of the bright green pins but could be a dark green one.  I've rotated the pinout to match the chip on the board.

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If you're lucky there's a visible trace to the pin it's connected to, in which case you can scratch it off and solder a long bridge to the other bridges (not the diode one) or if it's on the corner you could solder to the chip leg.  I hope your multimeter probes are nice and pointy, if not you might need to tape a pin to one of them.
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Offline topopo jr

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Re: Please Help! Trying to fix Keyboard PCB
« Reply #16 on: Sat, 15 May 2021, 21:00:41 »
Yes it has been opened before since a friend bought it used and put it on me to repair it  ^-^

And you were right, under the copper there was a small hole (sorry for the quality) that went to the pad, but I also noticed that it came to the other side of the pcb (Inside the blue circle), and it was scraped a little. I then did what you told me to search for the chip pin that gave connection to that little hole, and found that the 3rd pin from the bottom right made my multimeter ring.

Alright so before I begin working on that tiny-scary chip, the question is, I have to connect a cable from that pin to the switch, following that green line?

Offline topopo jr

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Re: Please Help! Trying to fix Keyboard PCB
« Reply #17 on: Sat, 15 May 2021, 22:55:19 »
VERY IMPORTANT UPDATE: I GOT IT WORKING!!!!!!!!!!!!!!!!!!!!!!

Thanks so much for telling me about the chip, I was at the point of not knowing what else to do. And before I went to get dinner, I thought "Wait if that hole goes to the chip and I need to connect it to the chip, then I can connect it to the hole" And it worked!!!! I used a little cable to connect the bridges and the little hole, fired it up and works all good now, I wrote this reply with it :)))))))

Again thanks so much suicidal_orange for telling me what to do!!!!

TL;DR: Connected a non-working switch to a hole that went to the chip (figure out what chip pin is first with multimeter).


Offline suicidal_orange

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Re: Please Help! Trying to fix Keyboard PCB
« Reply #18 on: Sun, 16 May 2021, 03:47:41 »
Oh dear, what was the previous owner thinking.  They've removed the trace from the pad to the small hole (a via) along with the pad then added some copper to short the pin to the ground plane they scraped.  They had even scraped the pad on the back but didn't connect it :confused:

Good work on the fix, it was nice of them to make the trace visible so soon on the back to make it surprisingly easy to see.  Maybe these professional PCB designers I often complain about aren't so bad...

I hope your friend enjoys their new board :)
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