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ortek_service · 27th Mar 2021, 12:05 am

Good to hear you've made it back - Luckily I only had a bit of a headache for about a day after mine (often similar with flu one), but it's a bit random how people I know have responded from nothing to a few days.

If the keyboard's data outputs go directly to the main custom IC, then it would seem that it's output circuitry has gone a bit faulty. Otherwise, there may be some external level-converters etc. that may be at fault, so would need to Rev.Eng that circuitry, to see what might be wrong.
But if the Main IC is responding to all key matrix line inputs, producing outputs, and just some switches not working, then it would seem the main IC is mostly working (presumably producing the right codes) and it should be possible to convert the -12V levels to 0V ones, while retaining the +5V high levels.

I presume that there was a small silicon chip / die etc. fitted on that ceramic substrate, and is completely missing - so couldn't be resoldered, if it was originally and not wire-bonded etc.
Might have to have a look inside a good one, to compare, with a close-up shot.
I wonder if Micro-switch bought these Hall-effect ceramic-substrate SIL-modules as an off the shelf product, or whether they are custom to them?

27th Mar 2021, 12:05 am	#110
ortek_service Octode Join Date: May 2018 Location: Northampton, Northamptonshire, UK. Posts: 1,440	Re: The Transam Triton Personal Computer Good to hear you've made it back - Luckily I only had a bit of a headache for about a day after mine (often similar with flu one), but it's a bit random how people I know have responded from nothing to a few days. If the keyboard's data outputs go directly to the main custom IC, then it would seem that it's output circuitry has gone a bit faulty. Otherwise, there may be some external level-converters etc. that may be at fault, so would need to Rev.Eng that circuitry, to see what might be wrong. But if the Main IC is responding to all key matrix line inputs, producing outputs, and just some switches not working, then it would seem the main IC is mostly working (presumably producing the right codes) and it should be possible to convert the -12V levels to 0V ones, while retaining the +5V high levels. I presume that there was a small silicon chip / die etc. fitted on that ceramic substrate, and is completely missing - so couldn't be resoldered, if it was originally and not wire-bonded etc. Might have to have a look inside a good one, to compare, with a close-up shot. I wonder if Micro-switch bought these Hall-effect ceramic-substrate SIL-modules as an off the shelf product, or whether they are custom to them? Last edited by ortek_service; 27th Mar 2021 at 12:12 am.