*** M E M O R U M ***

Hi,
Just joined today, and now I have a question.

Does anyone know what might be wrong with one of my MTXs that prevents the 2 reset keys resetting the machine? (in this case it is one of the series 2 machines)
All the other keys work ok, and I have checked and double checked the connector cable at each end, plus in the middle for splits....nothing showing up.

I once had a similar problem with a very early MTX500 years ago, but cannot remember the solution.
I faintly remember that the reset keys are wired to the CPU in some way, and that they reset by cutting the timing signal and/or power whilst depressed. Am I on the right track?

Thanks for your attention.

Mike

Hi Mike,

just saw this - I have not logged in here for a while. It's a bit quiet here unfortunately, the Facebook group seems a bit busier. Hopefully, things will pick up here in time.

You've probably done it already, but have you tried swapping the keyboard just in case it's a duff key before we get into the key decode logic?

regards
Dave

p.s. - The Second version of the MTX Operators manual (The Phoenix Edition) is available here http://www.primrosebank.net/computers/m ... anuals.htm. It contains copies of the schematics for the circuits - you can either download the whole manual, or just the Tech Pages. The MTX Service Manual is also the same page.

The reset circuit is shown on the second circuit schematic and is connected to J1 (the keyboard connector) pins 19 and 20.

Hi Dave,
Thanks for the reply.

Yes, it works fine when I swapped the keyboard across from one of my other systems.

Now I am assuming that like all other things MTX/FDX/SDX, the bolts underneath the keyboard will undo and I can easily check out the circuits etc. beneath?
Or will it be a case of easy to take apart, but a real pain to get it all back together?

Yes I have the Phoenix manual here, just looking now.

I could have sworn that there was mention of something like this in one of the issues of Memotechniques back in the late 80s/early 90s.

Many thanks
Mike

Hi Mike,

Yes, although I have not done it, the keyboard comes apart by unbolting the steel backing plate. You should be able to check the keys with a meter, but I don't know how easy it's to actually replace one. Claus (the owner of this forum\website) has had a keyboard apart and could not see how to remove just one key.

Good luck! - Let us know how you get on, I never had any copies of "Memo techniques", if you have them, then maybe a trawl through them will refresh your memory?

Regards
Dave