Since about this time of year in 2008 I've owned a Zenith 12B13C52 chassis Boyden cabinet hybrid Chromacolor that I bought from Doug (DRH4683). I've managed to keep it in at least weekly service as my main watcher. It has probably not had less than 6 hours a week when I'm not on vacation or rare times it has not been watchable for that long due to breakdown.....It is not uncommon for it to get 5-10 hours a day every day for weeks on end. I've ran it so much that about 4 months ago I had to change the HO tube socket since it was too charred to make reliable heater contact.
The black matrix 23VAXP22 Chromacolor CRT still has usable emissions, but at least one of the guns is not far from dropping off the bottom of green.
I've been having HV issues with it lately. There were intermittent arcing noises that resulted in dark horizontal streaks on the screen. Eventually the HV went out and it sat for a few weeks (I had to figure out what to do with the 210LB set on top of it). I dug into it this weekend and today and I'm either about stumped or I've got a weird problem. The H out has correct grid biases, and the HV reg seems to have plenty of range above where the HV stops rising with it. fly is cool-ish after 30 min on. I've cleaned the HV cage checked the HV leads and even replaced the HV rect fill winding, but I can't get consistent HV.
It seems like the CRT is loading it down...I recently pulled the CRT socket with maybe 4KV of HV and watched it shoot up to 20KV. I then reconnected the CRT socket saw a reasonably bright/normal raster once it re-warmed (hv dropped ~2-3KV) then a arc that seemed to come from the neck and HV started to drop like a rock with brightness (took about 5 sec from CRT re-warmup).
I think the CRT might be getting gassy, but testing it shows no gas. Could it be just gassy enough for this to be intermittent, or am I going crazy. I hate to doubt one of the best CRTs for longevity, but I'm running out of ideas. I wish I had the right adapters for my RCA/telematic color test jig!