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Keyboard repair
10-19-2021, 06:21 AM (This post was last modified: 10-19-2021 06:24 AM by teenix.)
Post: #1
Keyboard repair
Hi all,

Just thought I'd pass this on in case of interest to someone.

I was repairing a HP65 for someone and 5 of the key strips had cracked key domes which makes the key presses feel mushy. I used a corroded 45 as the donor and replaced 4 of the strips. I missed one after reassembly and had to do a fifth. It is a bit fiddly to do but seemed to work out ok.

If you try and pull the strips off, or lever the strip off the welds, the strip will deform or tear.

I used a drill press and supported the board on a piece of wood to keep it lying flat above the contact pins and used a 1mm drill bit to drill through the tiny spot welds but not into the circuit board (as much as possible).

Luckily most of the spot welds are not that hard to drill out. Most times as soon as the drill starts to break through the strip, the spot weld gives way. Some had already broken away from the board, but you still need to drill a hole through the strip if you want that particular strip as the donor. You have to be careful and not rush things to avoid the drill catching in the metal and ruining the strip.

Once the strips are removed, the recipient board and donor strip(s) can be cleaned up.

I positioned the strip on the board with a piece of tape at each end.

I used a soldering iron with a medium point tip and soldered through the 1mm holes in the center of the strip and onto the gold plated board beneath trying not to solder onto the dome area. I held the strip down against the board with a scriber tip which will not draw heat from the soldering iron which has enough to do. I then removed the tape and soldered the other points progressively moving to each end to make sure it would sit flat against the circuit board.

As each solder point is the same as the original spot welds, the strip will be help down firmly enough for use.

The top and lower 3 strips were replaced in the image, I had to do a fifth for the failed enter key later on.



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10-19-2021, 12:28 PM
Post: #2
RE: Keyboard repair
Thanks for this Tony, I still have the job to do but have been kicking the can down the road. This helps.

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