VT105 troubleshooting

As part of my PDP-11 haul, I have two VT105 terminals. I powered up the better-looking of the two terminals this evening, and it doesn’t show anything on the display. Before I dig too deep, I thought I would probe the collective knowledge of this group for troubleshooting tips.

The symptoms are:

  • The terminal beeps at power up
  • Keyboard LEDs flash and then the ON LINE indicator lights at power up or with Set-Up 0 (RESET)
  • Key clicks sound when keys are pressed
  • Set-Up functions that manipulate the keyboard LEDs appear to operate normally
  • I can hear the CRT power up and power off, so it appears to have HV
  • I cannot hear the CRT HV whine during operation; while I cannot hear CRTs as well as I could 20 years ago, I can still normally hear them. I can certainly hear my TeleVideo 910!
  • There is no picture on the screen whatsoever. No cursor, no set up menu, nothing but a black screen.

The VT105 has a soft brightness configuration, and I have attempted to adjust it using Set-Up and the up arrow, to no effect.

Any suggestions for common failures in the VT105 (or VT100, which I believe is architecturally similar?) that might cause this, before I start probing around?

After ruminating on this over night, I’m wondering if I can hear the HV hit and recede but not the whine because it has HV but no horizonal sweep. I guess that’s a place to start.