I've got a BMC-20, s/n BH8009039H, with a control upgraded to MAX 32. It has the twin-CRT text/graphics Ultimax console, and Fanuc spindle and servo drives. I bought it used, and have been having trouble getting it running.

The console, which had been working OK, developed a heat-related problem with the left-hand text CRT, losing sync after 5 to 10 minutes of power applied. The graphics CRT worked fine.

This machine uses a board in the console: "CRT Controller 2 PCB" (p/n 415-0174-002 Rev G) to create the video and sync signals for the text CRT only (apparently, the graphics CRT is driven by a daughter-board on the main CPU in the Multibus). I checked the video signals on the CRT Controller 2 board's J1 10-pin IDC ribbon cable connector, and found that the horizontal sync on Pin #7 was dead (should have been about 16.2 kHz square wave for CGA).

I figured I had a bad CRT Controller 2 board, likely a bad oscillator or divider chip, and that I would troubleshoot it later. Well, I finally got back to it and things are much worse:

When the power is turned on, all 20 green LEDs on the Ultimax console turn on steady and never turn off. The text CRT is blank. Pressing the "Graphic" button doesn't turn on the graphics CRT. The Multibus CPU is booting, and the power input strip TB52 on the console's distribution PCB has good DC power on it:
Pin #8: DC return
#7: +4.94 VDC
#6: DC return
#5: DC return
#4: -12.60 VDC
#3: +12.09 VDC
#2: +4.92 VDC
#1: +4.92 VDC

I'm really not at all sure what direction to go with this troubleshooting. Can someone help me out with a suggestion? I've got scopes, meters, and a fair bit of chip-level experience, but no spare boards.

Thanks very much!
Dave