Sony KV-20M20 - HV but no picture, curiosity

[RetroHacker]

Recent find, a Sony KV-20M20. This set has *clearly* seen a ton of use, the tube has heavy QuickDraw burn-in. When I grabbed it I didn't notice this, but it was immediately apparent when I got it home. This was likely on 24/7 for a very long time, and has no hope of ever producing a usable picture again. But, I figured I'd fire it up and see just how bad it was. But, the screen is blank. Completely and totally. I'm getting HV, sound, everything appears to be fine. But no picture. This model doesn't have a standby light - I'm used to some Sony sets that would flash the standby light in a error code, one of which could be that the tube had such low emissions it wasn't switching on the video. I haven't opened it up yet to try cranking up the G2. What I can't remember is in this situation, can entering the service mode bring up the display regardless of the feedback it's getting from the tube? I tried the usual Display/5/Vol+, and Display/5/Vol- that I remembered with no effect. It's been a while since I worked on one of these.

I could be mis-remembering a lot of this. This set might not be that smart, and it's just a failure of cathode drive voltage or something. I CAN see the filament glowing in through the side of the casing, so there's that.

Really just curious here - with this much screen burn it's basically scrap, but it would be interesting to see just what kind of a picture it can still produce.

-Ian