Hi all
Long time lurker, first time poster.
I’m having some issues with my ASR-10 keyboard. The display is going into test mode and it won’t boot.
I’ve checked all fuses, ribbon cables and headers for continuity and I’ve purchased components to do the following:
- Replace all electrolytic capacitors on all PCBs
- Replace all diodes and the 2 x 5V regulators in the power supply
- Replace the 224 and 104 ceramic caps that are connected to VCC and control voltage for the 7555 IC timer circuit on the keyboard PCB.
I’ve previously replaced all caps and regulators in an EPS Classic PCB without issues although that was to address an issue with noise, not because it wasn’t booting.
This is all based on common problems I’ve gleaned from various online sources.
I think I’m at the point were I need to start probing. I’m confident with analogue circuits but I have no experience following digital data with a scope.
I’m in Australia and unfortunately I’ve not been able to identify anyone locally who could help me out and I have no desire to send it internationally to be repaired. As such, I’m looking for recommendations for a suitable tech to consult and hopefully help me diagnose and repair it.
Grateful for any suggestion.
Thanks
Kris