GE console CRT arcing - Videokarma.org TV - Video

Chad Hauris · #1 05-12-2004, 07:43 AM

I've got a 1969 GE color 23" console, tube type. Circuit breaker was tripping, so I replaced a bad filter cap. This got the HV back, but now there is a purple glow in the CRT neck. There is no picture on the screen.

The CRT filaments light up. All other times I had this much arcing, the CRT filament did not light. This seems like a rare combination of symptoms. I added another ground wire from the CRT degaussing shield to the chassis.

The CRT base is mostly disintegrated, just the wire pins are there. This set was from a repair shop...it has apparently sat there since the late 70's.

bgadow · #2 05-12-2004, 08:22 AM

I was having a similiar problem the other month with the CTC-31 and it turned out to be a bad video amp tube, somehow. Before that I always thought such a glow meant only doom for the crt.

Chad Hauris · #3 05-12-2004, 08:32 AM

Thanks Bryan. I don't think I have a sub for the Video output tube on this GE, it looks like it is mostly compactrons. I may try out this chassis on another CRT and see if I get the same kind of arcing.

peverett · #4 05-16-2004, 12:14 AM

I have an ample supply of TV tubes. Post a number, and I will probably have it. I am in Austin, TX, and sending you a tube would not be a problem.

kc8adu · #5 05-17-2004, 03:20 AM

i have seen this glow when the focus voltage was missing or excessive beam current was drawn.
it could still be a gassy crt though.

Chad Hauris · #6 05-17-2004, 06:40 AM

I have tried looking at this some more: disconnected the video output tube with no difference in symptoms. I pulled off the CRT socket and turned on the set...there was no arcing. Then I tried disconnecting the screen leads and this decreases the severity of the arcing, although there is still somewhat of glow among the tube elements.

Somehow the HV is finding a discharge path back through the base elements of the tube as there is no arcing/glow when the CRT socket is disconnected. I'll just need to try the chassis out on another CRT for a conclusive test. I don't have an HV probe so cannot directly measure focus voltage.

This is part of a group of sets I got that had been stored in a repair shop for more than 25 years after the repairs were declined for whatever reason...I am seeing some more difficult problems in these than the sets I usually get from estate sales, etc. that just have normal age-related problems.

andy · #7 05-17-2004, 09:03 AM

Try removing the CRT socket and grounding the pins of the CRT. If there's any glow, the CRT is bad.

kc8adu · #8 05-17-2004, 10:02 AM

if it is among the elements as you state it is shot .
glow inside the neck on the inside of the glass is ok.

Quote:

Originally posted by andy
Try removing the CRT socket and grounding the pins of the CRT. If there's any glow, the CRT is bad.

Jeffhs · #9 05-24-2004, 01:58 AM

Quote:

Originally posted by kc8adu
it could still be a gassy crt though.

That was going to be my answer as well. I've heard of color sets whose CRTs went gassy from blooming which was allowed to continue far too long. One set's CRT drew so much current from this that it also caused an arc across the base of one of the color demodulator tubes, which cracked the glass. One other set's CRT arced so badly it cracked the glass around the second anode button, but somehow (don't ask me how)

the CRT retained its vacuum.

FYI: If you notice the picture blooming out of focus on a color set, turn the set off at once and track down the problem before operating it again. If you don't do this, the CRT will likely become gassy from an unusually heavy current overload.