I got myself two Apple M0110 keyboards. One in good cosmetical order and complete and another PCB with a lot of non working switches. Unfortunately the good looking one is completly dead. Reading the net about the M0110 I found that using a wrong phone cable can cause the keyboard controller go bad. This seems to be the case here. It has an Philipps MAB8021P controller on the PCB.
The other PCB is working, at least partially. A lot of the switches are sticky and most of them do not register at all. But the controller is working. Its an Intel 8021.
I learned that the Philipps is a licensed copy of the Intel 8021. I switched the ICs around but that does not work. Both keyboard PCBs have the same rev number 8200103A, so they are the same. I dont know why switching the ICs between the two boards should not work. Besides a 74LS123 (which is ok) there are no other ICs and I cannot spot any difference between both boards.
I rather would switch the controller than desoldering and soldering 10 to 20 keyboard switches to make one fully working keyboard out of the two.
Any classic Mac experts around who can solve the mystery?
Apple M0110 keyboard dead controller
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feltel
- Location: Germany
- Main keyboard: Unicomp Ultra Classic
- DT Pro Member: -
- Contact:
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fms
- Main keyboard: IBM Model F XT
- DT Pro Member: -
I fixed one of my M0110 which was also failing by recapping it. I'd recommend JDW video about it: https://www.youtube.com/watch?v=vz2NGF5Vuao
Not sure if its your case, but if your PCB is broken, I also found that Caymac Vintage are producing replacement PCBs for these board, you'd need to provide all the components though https://ko-fi.com/s/e913ca37b3
Not sure if its your case, but if your PCB is broken, I also found that Caymac Vintage are producing replacement PCBs for these board, you'd need to provide all the components though https://ko-fi.com/s/e913ca37b3
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feltel
- Location: Germany
- Main keyboard: Unicomp Ultra Classic
- DT Pro Member: -
- Contact:
Tbh, I dont think this is a cap related issue.
I have two (identical) M0110 PCBs/Keyboards. One with an Intel 8021 keyboard controller which works partially, due to a bunch of bad switches. Another PCB with an Phillips MAB8021P keyboard controller. It does not work at all. I cross-switched the controllers around. The Phillips IC does not work in the Intel PCB and the Intel IC does not work in the Phillips PCB. There must be some unknown difference between the two boards. I have to compare the passive components, resistor values, ....
To get further I desoldered all switches from the Intel PCB. I checked all switches and 12 are dead. They dont conduct when checked with a multimeter. I took the opportunity and deep cleaned the PCB. Its worth it. I'll grab the missing switches from the Phillips PCB, but it would be a waste to declare it a parts donor. 
Maybe there is a way to revive the bad switches and some way of replacing the possible dead keyboard controller.
I have two (identical) M0110 PCBs/Keyboards. One with an Intel 8021 keyboard controller which works partially, due to a bunch of bad switches. Another PCB with an Phillips MAB8021P keyboard controller. It does not work at all. I cross-switched the controllers around. The Phillips IC does not work in the Intel PCB and the Intel IC does not work in the Phillips PCB. There must be some unknown difference between the two boards. I have to compare the passive components, resistor values, ....
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- PXL_20241117_132713084.MP.jpg (2.77 MiB) Viewed 259 times
Maybe there is a way to revive the bad switches and some way of replacing the possible dead keyboard controller.