ASR-10 Virtual Consultancy

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

Not booting is a common problem for this keyboard, with many suggestions pointing to a bad connection or poor solder joint.

see if anything on page 23 helps.

first and for most, never pull the ribbon cables - instead pry them off using the tool suggested in the service manual.
I have the rack version, my analog board died. I replaced the board and now it boots up. I was able to figure our that the analog board was at fault from the service manual when it came up with the error codes. But you should also check voltages to all the other boards to make sure they are all up to their normal values, and if they are not then chances its the ribbon cables.
Thesonic in California is the only place i know that strictly specializes in ensoniq products. look him up and call him. he’ll let you know what to look for and where. And it maybe just a board which you can send to him and he’ll send a working one that he has in stock. He also will do that to keybeds - repairs them and does an exchange when you send yours in.