axur-delmeria wrote: ↑Mon Jun 29, 2020 2:08 am
Let me know if you succeed with that trace redrawing idea.
I want to update on this now that I think I found the proper way to tackle this problem.
Recently I have gotten a lot of 6 of laptops and surprise surprise 3 of them came with broken keyboards. And now I can't believe I have the capability to fix all of them!
One has a broken Windows key, so whatever.
One has a broken escape key, annoying but not the end of the world.
One has two columns of keys not working, now that's surely something I have to fix.
None of them are ThinkPads but I think once you get the keyboard open, the way to fix is about the same.
The opening process for the keyboard varies vastly one model to another, and sometimes even the same model with different switches.
For cases where the fault is happening along the edges of the keyboard (the Windows key and the escape key for example are all on the corners on those keyboards) is usually much easier and you only need to clear the switches and keycaps along that surrounding area.
As for the case of the 3rd one, where 4, 5, r, t, f, g are not working, I have to remove every single keycap but that doesn't require me to remove the switches as the switches come off with the top layer shield on those (but they are slotted in place so touching the keycaps send them flying all over the place)
On the two with each one key not working (they are the same keyboard), they were the easiest to repair. The membrane layers on them comes right apart as soon as you remove the keycap and switch.
Then I just need to follow the traces with my eyes to see where they go, and fortunately they all go to a nearby key, so I just take the pen and draw the traces connecting both pads. I have to draw to the pad itself as the traces are all covered in this substance that scratching it off also takes the silver paste with it.
Put the keyboard back together enough to test. Once all keys work, open it back up and apply a clear coat protecting the traces you draw. The conductive pen I have is meant for kids to get creative, the traces are meant to be easily scratched off if you make a mistake.
So a clear coat is required so the ink doesn't get smudged within the layers and at best ruin your repair, at worst short to other keys that now you have key shorts.
The third one is more involved. It's from a spill resistant keybaord that went beyond just membranes. It used a metal shield on top of the membrane to protect from liquid spills and such. This one is also broken in the centre area and not the keys by the edges.
I have to take off every single key cap (they are dirty and needs washing anyway)
Then there are those metal poles that I have to unsnap the shield from. I have to undo the left half of them to get the traces under 4, 5, r, t, f, g visible.
What's more complicated with this one is that the switches are also mounted onto this small bracket that are individually mounted onto the metal shield and falls off by the touch of your finger. So they keep falling off when I am working on the membrane.
It's also even more interesting that this is a single layer membrane, where each pad is separated with left and right side and your dome makes direct conntact with the pads to connect them.
There is also a pointing stick on this one, so the traces near the pointing stick go all squiggly.
The trace that comes from those keys actually go from the f key around on top of the g, h, j key and then goes around the pointing stick to the b key, and then to the bottom where the keyboard cable goes.
I am extremely fortunate that there is a b key still connected in that trace, otherwise I have to wire directly to the keyboard connector and it gets really messy!
I am not going to be squiggly with this ink as there is 1Ohm of resistance roughly every centimetre of distance.
Fortunately dell covered all of the traces on this one with the black layer that's this time forgiving in the traces when I try to scratch off.
So I scratched off near the g and b keys, go the shorter way around the pointing stick and draw on top of other traces and it works!
Need to apply clear coat on this too and then use hair dryer to accelerate its curing time.
Then putting back together this keyboard is tedious. I have to superglue half of the metal poles because I have to bend the shield to get it off and of course then those poles don't hold up well anymore.
I have to also slide the brackets that hold the switches underneath the shield while supergluing a small batch of those poles at a time to secure more of these brackets down and then proceed slowly.
But well after a long struggle with this keyboard (I almost gave up seeing how difficult it is just to open it), it works great and now it's also cleaner than ever because of course I used that opportunity to throw all the keycaps under soap water and then brush on the shield.
Even though I had no such luck with a ThinkPad T520 keyboard last time that I tried on 3 of them, maybe you can find this useful nontheless.
For testing, I typed this entire message up on one of the repaired keyboards and no problems so far.
Well I cannot believe how much experience I have gained by getting these machines to work.
I am also glad that the clear coat applicator on my car paint repair pen works great with the circuit scribe conductive ink that's relatively cheap for the special thing it is.
Without the clear coat the ink can easily get smudged (it's designed for kids to draw on paper and even then it can also be easily scratched to break so errors can be quickly fixed) and at worst short out other traces and leave you worse off than before!
Pics will come soon.
Try this ONLY if you have nothing to lose, like the case where two columns of keys don't work so the keyboard is essentially useless.
