26 Nov
2025
26 Nov
'25
8:36 a.m.
I don't know what the internal construction of the TRS-80 keyboard is but
there a number of products targeting remote controls with a
conductive-rubber bubble over a gold-plated pcb.
These vary between paints, entire keypads and small conductive rubber discs
which cover the original rubber patch. As long as the bubble hasn't cracked
but only the conductive material has worn thin, these last seem as though
they might be the best and least invasive repair option. Easily available
on ebay, some from reputable suppliers - maybe chemtronics ?
https://www.eevblog.com/forum/repair/best-method-to-restore-conductive-keyp…
On Wed, Nov 26, 2025 at 1:10 PM me--- via cctalk <cctalk(a)classiccmp.org>
wrote:
I just acquired a TRS-80 model 102, my first of that
model.
Everything is great other than three keys. The 2 keys works
intermittently,
q, and [ don't work. Having checked the schematic, the keys have no
commonality on the circuit.
Before I pull the cap off the switch, I know that the rubber dome inside
has
material on the inner part that meets with the silver contacts to complete
the circuit. I'm told this material will wear out or lose conductivity.
I reflowed the solder joints on the pcb and this didn't help. Other people
have simply replaced the rubber dome from another dead 102's keyboard.
But,
I'd rather attempt applying new material inside that dome.
I'm hoping there is an inexpensive and mainstream solution I can buy at
home
depot or something.
Any tips?
Daniel
sysop | Air & Wave BBS
finger | calcmandan(a)bbs.erb.pw