Need Help ! Model M stop registering some keys after Nut and Bolt mod.

[Tangtawan]

Hello,

This is my first time doing nut and bolt mod on the Model M. Its a 1987 SSK. After I reassemble the board together, I tested every key and all seems to register without a single issue. However, I left the computer on for 15 mins and as soon as I come back I found that some keys were not registering anymore; so I use Auqa's KeyTest and it shown that two vertical rows did not register. The keys seems to click just find though, just that it wont register, what should I do? and is this common problem after bolt modding? (pic in attachment)

Thanks.

[fohat.digs]

I do not know the precise answer to your question, but here is a tangent that may be significant:

The tightening of the bolts determines the pressure between the plates. I recommend the same pressure on all the screws, and "looser-rather-than-tighter" as the first option for adjustment.

Is it possible that the screws in that area are tighter or looser than the others? I recommend loosening all of them at least half a turn, then slowly adjust until they all feel the same.

[mike52787]

Heres some really easy things to try,

loosen or tighten the bolts in the affected area

clean the connections on the end of the ribbon cables

[Tangtawan]

Thanks for all the comments. I did an experiment and found a weird problem. As soon as I took off the top cover, all the keys registered again; but as re install the top cover- the same row stop registering again. Is it possible that the membrane trace on the ribbon cable is kinking and loses contact? Before bolt modding, I was able to put all the ribbon cable inside the case without a problem, but after bolt modding i can no longer shove all of them inside, so i need to shove it manually and might causing it to kink? Its confusing how bolt modding will affect the length of the ribbon cable.

[chyros]

This is almost certainly an issue with the tightness of the bolts or the ribbon connector. Kinking the ribbon shouldn't matter, but it might not be properly seated. Also, make sure the bolts are roughly equally tight. Don't go overboard with tightening them, but don't have them loose either.

[lemur]

I did a bolt mod on a board and I had a similar problem.

I ended up testing the membrane with a electrical meter and found that in the process of completing and tweaking the bolt mod one of the contacts on the ribbon cable had degraded to the point where it just wouldnt work anymore.

i think a replacement membrane is under $20 from unicomp, if you determine that is the issue.

its my suggestion: test for continuity for all the leads on the ribbon cable.

edit: oops you mentioned its an SSK..... maybe a bit harder to get a membrane for one of those! good luck