fm2606
Member
I have a TRS80 M3. When I 1st got the computer about 1 month ago and turned it on nothing came on the screen but the drive sequence seemed to be correct. I replaced the RIFA caps on both power supply boards, cleaned up the computer a bit and put it all back together. Initial power up was promising as a green rasterized circle appeared (see link below) and the drive sequence again seemed correct. By correct sequence I mean the bottom drive comes on, then the top drive comes on momentarily and then the bottom drive again and that's it. If I press DELETE and RESET the sequence starts over.
Now however, nothing comes on. With the video cable attached to the video board the bottom drive comes on longer than the normal sequence, then the top drive comes on and this time runs for about the same amount of time as the bottom, it then stops and then the bottom drive comes on again longer than what seems it should. DELETE and RESET do nothing in this set up.
If I unplug the video cable, the normal drive sequence starts again and once completed if I press DELETE and RESET the sequence starts over.
I have 12V at pin 7 on the video cable. The two 4-pin connectors on the CRT power board have +/- 5V and +/- 12V.
When I tore down the computer for a cleaning I never did open up the back plane that holds the motherboard and drive controllers.
Any suggestions on how to proceed to trouble shoot this would be greatly appreciated.
https://imgur.com/2r1kUZ2
Thank you
Curt
Now however, nothing comes on. With the video cable attached to the video board the bottom drive comes on longer than the normal sequence, then the top drive comes on and this time runs for about the same amount of time as the bottom, it then stops and then the bottom drive comes on again longer than what seems it should. DELETE and RESET do nothing in this set up.
If I unplug the video cable, the normal drive sequence starts again and once completed if I press DELETE and RESET the sequence starts over.
I have 12V at pin 7 on the video cable. The two 4-pin connectors on the CRT power board have +/- 5V and +/- 12V.
When I tore down the computer for a cleaning I never did open up the back plane that holds the motherboard and drive controllers.
Any suggestions on how to proceed to trouble shoot this would be greatly appreciated.
https://imgur.com/2r1kUZ2
Thank you
Curt