How to fix Model F PCB

[joshwyant]

First post!
I bought my first Model F for $99 about a little over a year and a half ago. It needed a lot of care and restoration. The keyboard worked, but wouldn't type odd numbers at the top. It looked like the corresponding trace was broken on the PCB. I tried fixing it myself, but it wouldn't work no matter how I repaired the trace. I tried copper tape, conductive ink, and even soldered a wire. I got continuity either way, but the odd keys just still wouldn't work.

All I can think of is that either the trace needs to maintain a certain capacitance that was more precise when the trace was covered by the film, or maybe the controller circuitry is faulty.

I think I botched the job anyway lol. I accidentally lifted up more of the trace and broke it. There are spots of solder residue. And, I scratched it trying to scrub the solder off.

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[Muirium]

As it happens: I have a spare XT PCB and controller if you’d like them. Free for the cost of shipping. A good fallback if your hacking doesn’t work!

Only problem is I am over here in Scotland. Tends to make shipping very expensive over the ocean. But I do travel to America later in the year, if you still need them then.

[joshwyant]

Oh, nice! That would be cool either way, how much do you think shipping would be? Where are you gonna be in the US?

[gipetto]

You could measure the capacitance of each good row with an avr transistor tester, then put an appropriately sized capacitor on the bad row to match the rest, after the trace is repaired. that's what i would try at least. the hard part is finding room for the capacitor, and the trace repair. perhaps it could be wired outside the pcb sandwich.

[thefarside]

As it happens: I have a spare XT PCB and controller if you’d like them. Free for the cost of shipping. A good fallback if your hacking doesn’t work!

Only problem is I am over here in Scotland. Tends to make shipping very expensive over the ocean. But I do travel to America later in the year, if you still need them then.

I’m in the USA and also have a spare PCB and controller you can have for the cost of shipping if you like. Send me a PM if you’re interested.