blue glow in HV recitifier
 

I noticed this when looking at my CTC-7 as HV comes up the HV rectifier will glow blue like its gassy, then as soon as you hear the crackle around the CRT and the raster comes out the blue goes away. So its only glowing for a few seconds. It's pita to get at it and replace with the flyback cage installed, so I was going to pull the chassis and remove the shield to give me better access to see what is going on. The set is working fine, but the fly does get hot after about 30 min even with the fly current only at 180ma.

Electron bombardment, totally harmless. Audio output tubes do the same thing, just watch them with the lights off. If it were even remotely gassy, it would arc over. I wouldn't worry.

I agree with miniman, but on B&W sets of that era, HV rectifiers glowing excessively on startup was sometimes caused by excessive high voltage until the CRT started pulling it down.

You might monitor the HV during startup to see if this is happening, and if it is, check the HV regulator.

It probably is not the cause, but this check can be cheap insurance.

Jas.

will do. I am pretty sure the HV is regulating (I can see the shunt plate glow change as the brightness is advanced. I think I will make a video of it just for reference. Thanks for the input guys.