Keyboard oddity

Discussions about Sinclair ZX80 and ZX81 Hardware
Post Reply
RWAP
Posts: 1348
Joined: Thu May 08, 2008 8:42 am
Location: Stoke-on-Trent, UK
Contact:

Keyboard oddity

Post by RWAP »

Now I know that this might be a faulty membrane, but it is not an issue I have come across before.

I supplied a customer with one of my replacement ZX81 membranes and he reports that it works fine, except for the V key, which is not always recognised by the ZX81.

Any suggestions as to what else it might be? I will send him another membrane to try in the meantime.

Rich
User avatar
PokeMon
Posts: 2264
Joined: Sat Sep 17, 2011 6:48 pm

Re: Keyboard oddity

Post by PokeMon »

Could be a mechanical problem with a kind of mould under the V - did he check when not glued to the case first ? Maybe some disturbing rest of glue under the membrane ?
RWAP
Posts: 1348
Joined: Thu May 08, 2008 8:42 am
Location: Stoke-on-Trent, UK
Contact:

Re: Keyboard oddity

Post by RWAP »

I did think of that but of course, once stuck down, it is too late to lift the membrane and check for glue residue! :(
User avatar
1024MAK
Posts: 5102
Joined: Mon Sep 26, 2011 10:56 am
Location: Looking forward to summer in Somerset, UK...

Re: Keyboard oddity

Post by 1024MAK »

If it is always a single key and all others work correctly, it does point to either a uneven surface (old glue or dirt) or a fault with the membrane. Even more so if the key works when pressed from one direction, but not another direction.

Mark
ZX81 Variations
ZX81 Chip Pin-outs
ZX81 Video Transistor Buffer Amp

:!: Standby alert :!:
There are four lights!
Step up to red alert. Sir, are you absolutely sure? It does mean changing the bulb :!:
Looking forward to summer later in the year.
monzamess
Posts: 25
Joined: Sat Jul 08, 2017 8:39 pm

Re: Keyboard oddity

Post by monzamess »

Temporarily jumper the two pins on the motherboard keyboard connectors that make "V" and if it registers with the computer, then it's definitely a membrane problem.
Post Reply