Classic keyboard swap in x230 gone wrong

[Linas81]

Hello everybody, I have a quite big problem. This was my second time doing the classic keyboard swap and I accidentally taped the wrong side of pins (I taped the top connector bottom pins where it was the brown pins, instead of bottom connector bottom gold pins) and have burnt a trace on the keyboard, in doing that so, the mouse buttons don't work anymore. When I realised my mistake, I put the tape on the correct side of the connector, but unfortunately the mouse buttons still don't work. Except for those mouse buttons, everything else works perfectly on the keyboard (it types all characters and the touchpoint works.) Is there a way I could mend that trace so I would have full functionality or is it fargone?

Picture of burnt trace: https://imgur.com/7G8c64z

[atagunov]

Hi, I'm sorry to hear about your trouble. I'm afraid the messed up keyboard will be difficult to repair. The closest I've heard about this kind of repair is what is described in this post and following thread: viewtopic.php?p=847147#p847147

Pay special attention to post number 13 in that thread: viewtopic.php?p=847398#p847398

Spent an entire night and I managed to get one out of the three broken T520 keyboards working. To be fair I initially used liquid metal to connect the traces ...

As you can see success rate - even with prior experience doing the same on Dell keyboards is pretty low - 1 of 3 and requires lots of time. I was able to find used keyboards rather cheaply on ebay, it might be a better investment of time to just procure another working keyboard from somewhere..

P.S. I've seen a number of reasonably priced Thinkpad parts sold from Lithuania on UK ebay, you wouldn't be the seller would you?

[Linas81]

Ah bummer. No problem, thank you for suggesting. I think I will just leave it alone and accept it's fate as a 90% working keyboard before I screw up even more and use it in my t420 that I recently bought

Also, about the Thinkpads part part (ha), it is definitely not me, as I just recently got into Thinkpads and have just a x230 and a t420

[kfzhu1229]

As you can see success rate - even with prior experience doing the same on Dell keyboards is pretty low - 1 of 3 and requires lots of time. I was able to find used keyboards rather cheaply on ebay, it might be a better investment of time to just procure another working keyboard from somewhere..
P.S. I've seen a number of reasonably priced Thinkpad parts sold from Lithuania on UK ebay, you wouldn't be the seller would you?

I would like to update on that project... Well the "fix" on the keyboard lasted like 2-3 days before it broke again... At another spot... So clearly my repair technique (the final one that involves with a Circuit scribe conductive pen + clear coat) works well. I ended up using the same technique afterwards to repair 3 Dell laptop keyboards all with success!
It just seems like the silver paste printing on those keybaords are exceptionally weak and doesn't stack up as well as anticipated in terms of oxidation and corrosion if there are drops of liquid and such...
Anyway, if you insist, here's how I did my repairs (this guide is for the T520 but many of my points are from my success with the Dell keyboards):
1. Mark down all keys that are defective and see if there is a pattern.
2. Pry off the plastic cover on the power button and volume button (from the top).
3. Remove all keycaps and switches, deweld the plastic frame around that power and volume buttons. On the T520 keyboard, if all your broken keys lie in either the function row or the bottom section, you only need to remove the keycaps and switches from that said section.
4. Separate the top layer. I suggest you doing that from the bottom right as the areas where LEDs lie cannot be separated or the trace will rip and the LED won't work well again.
5. With the top layer gone, see how your broken keys form a pattern either on the top layer or the bottom layer, and thus identify the fault. Trace to the closest key that's on the same trace but still working.
6. Use conductive pen and draw over the membrane to connect them back up. If it is going on top of other traces, use clear coat first to insulate so you aren't shorting other traces.
7. Put the keyboard together and test if your fix work.
8. If so, seal your repair up with clear coat so the trace doesn't get smudged away
9. Put the keyboard back together.

EDIT: Just saw OP's picture. In his case the fix is easy if it's only the that single trace that's burnt (I think it is because I have the same spot burnt when I tested the T520 keyboard on a T530). You don't even need to fully remove the plastic frame, just deweld enough joints so you can stick the conductive pen inside and draw the trace, and remove only the keycaps and switches of F3-F10 as well as the keys on top of F9 F10.

[Linas81]

Now that you say it, I might even attempt it, as there was only that one trace that was burnt as the other one beside it is perfectly fine. As soon as I find a conductive pen and do the fix, I will post an update for it.

[Linas81]

Okay, so I dissasembled the keyboard and now found out that there are two pins burnt on the top layer of the pcb and at the bottom layer of the pcb. Could you give me some suggestions on how to proceed?

Picture: https://imgur.com/c4FTzsQ

[RealBlackStuff]

Left of the "burn-hole" are 3 horizontal traces, call them (from top to bottom):
hor-1
hor-2
hor-3
Above that hole are 2 burnt vertical traces, call them (from left to right):
ver-1
ver-2
You need to connect hor-1 to ver-1 and hor-2 to ver-2.
All others appear to be OK.

[Linas81]

My main problem currently is how do I connect the second pin from the left without bridging some contacts on the bottom pcb?

[RealBlackStuff]

Remove some of the black burnt stuff, scrape some of the existing protection of the 'burnt' traces, remove the dust/dirt, put a piece of Kapton tape on the bottom, then use the Circuit scribe pen mentioned above and connect the the traces using the old/burnt pattern.
When dry, put another piece of Kapton tape over that.
Instead of Kapton, you could also use some Sellotape/Scotchtape

[Linas81]

Okay got it. I'm going to order a conductive pen for pcbs and once it arrives next week, I will do the fix and will report on it. Thank you for your advice.

[kfzhu1229]

Okay, so I dissasembled the keyboard and now found out that there are two pins burnt on the top layer of the pcb and at the bottom layer of the pcb. Could you give me some suggestions on how to proceed?

Picture: https://imgur.com/c4FTzsQ

So this is the maker for the pen that I used: https://circuitscribe.com/
This one is meant for kids so it's non toxic and also easily erasable, so you absolutely need clear coating so it won't oxidise or smudge away afterwards!
I just used the clear coating from my car paint repair pen but maybe some expert here have better ideas.

Remove some of the black burnt stuff, scrape some of the existing protection of the 'burnt' traces, remove the dust/dirt, put a piece of Kapton tape on the bottom, then use the Circuit scribe pen mentioned above and connect the the traces using the old/burnt pattern.
When dry, put another piece of Kapton tape over that.
Instead of Kapton, you could also use some Sellotape/Scotchtape

Unfortunately tape won't work. I have tried before... While Kapton tape is better that the adhesion is pretty solid, what happens also is tape can flex at a different rate than the membrane and cause the ink over the tape to crack where the ink seeps down to the membrane...
With clear coat, you can apply that to the surrounding traces so that your pen won't short them (the tip for this pen is more like 0.9mm so pretty thick)
When applying the ink, since the plastic membrane is pretty smooth, it's hard for the ball on the pen to roll properly. What I typically do is I take the casing out of the pen and just blow with my mouth from the back of the pen to give extra pressure for the ink to come out, and this creates a thicker trace than just the 0.9mm tip!

[RealBlackStuff]

Alternative method:
make cuts in the traces where the black X are on the pic below.
Then use the ink-pen as per red arrows.
Put some Kapton tape over it to prevent corrosion.
https://i.imgur.com/vZdwQI0.jpg

[kfzhu1229]

yeah that's what I have in mind. Though I didnt think of cutting the places that lead to the hole.
Actually scraping the trace away is probably better as the membrane already sustained enough structural damage that cutting it might make it weak..

[Linas81]

A quick update. I just done the fix with the conductive pen and unfortunately the mouse buttons still don't work and it's probably a problem with the bottom layer keyboard pcb that is burnt. If you have any further suggestions, please post them.

[kfzhu1229]

A quick update. I just done the fix with the conductive pen and unfortunately the mouse buttons still don't work and it's probably a problem with the bottom layer keyboard pcb that is burnt. If you have any further suggestions, please post them.

Actually since I have broken and torn apart T520 classic keyboards with my bad luck of getting 3 of them in a row that turn out to be all bad, I think I can trace and find out where the mouse button is connected to in the traces. Assuming X220 will have similar wiring of the traces as the T520 it might give you an idea to see which trace to check.

[RealBlackStuff]

All xx20 machines can use the same keyboards.

The HMM has 3 KB columns, from L to R: Alps / Chicony /NMB
They have different colour pads under the keys:
NMB = red pads
ALPS = white pads
Chicony = grey pads
Also: the traces might be different between brands.