Keyboard Issues .. Some keys not working (new membrane)

Discussions about Sinclair ZX80 and ZX81 Hardware
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1024MAK
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Re: Keyboard Issues .. Some keys not working (new membrane)

Post by 1024MAK »

thedevworks wrote: Wed Mar 20, 2019 6:03 pm The only oddity I have found so far is the resistor pack just above the keyboard set. The centre post (The one I have an issue with) is reading around 6k resistance whilst the rest read 10k (Correct according to schematic) .. Could this be my issue.. or more of an indicator of an issue
RP3?
These are normally fairly reliable. Unplug the ULA and retest.

Mark
thedevworks
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Joined: Mon Mar 04, 2019 5:33 pm

Re: Keyboard Issues .. Some keys not working (new membrane)

Post by thedevworks »

Ok so that was a clue.. I found a short but couldnt see where..

I ended up purchasing a microscope, and within 10 minutes of setting it up I saw the issue.

Image

Scraped it with an x-acto knife a tiny bit.. and the whole keyboard works!

Now, it crashes when loading from tape, or saving.. But thats for another day!! :)

Thanks again everyone for your help!! .. Again..
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