Bryan's Philco TV-123

[bgadow]

Time for another update: there were some delays as I was out of town for a week on vacation, but I've been trying to tinker on the set for an hour or so each night. I've been scratching my head a lot, trying to figure out what was causing this large current draw in the horiz.limiting/damper circuit. I knew that, like all problems, the root cause was something simple. Finally, tonight, I stumbled upon it. I mentioned earlier that someone long ago had re-wired the set to use a 6AU4 damper rather than the oddball 6M3. I wired it back to original. I noticed that the filament wasn't lit and that's when I realized there was no ground to pin 2, an easy fix. For some reason it didn't occur to me to look closer-yep, they had simply moved the wire to pin 7 (correct for the 6AU4) and I totally ignored it. Internally in the 6M3 that's connected to pins 3 & 5...and the plate. So, yeah, I guess grounding the plate would cause that draw! The weird thing is that I'm certain I had yanked the tube and it didn't alleviate the problem-I don't understand how it couldn't. The good news is that the draw is gone.

I decided to do another quick and dirty power up with everything connected. While it would have been great to see "first light", what I did find were a few more things to troubleshoot: there is a 400mfd/50v cap (positive to ground) in the -25v circuit that blew. The purity circuit taps into this, among other things. I haven't replaced all the Black Beauties in that circuit so it could be as simple as that. And then, I briefly had some HV (I could hear it, smell the ozone, and there was a little snap-crackle-pop action going on) but then I lost it. No red plating of the horiz output; no raster, either. I'm not too concerned about it yet. All part of the "fun"!