RCA CTC...Something? poor HV output.

[rca2000]

I can see NO WAY....you ONLY have 12KV here. The pix is WAY too good--and full. 12 KV would NOT give a full raster--and focus woulod likely be VERY bad..


YOU DEFINITELY need to check your HV PROBE !! I'll BET...from that pix...you are getting at LEAST 23KV.

[Arcanine]

Originally Posted by rca2000

I can see NO WAY....you ONLY have 12KV here. The pix is WAY too good--and full. 12 KV would NOT give a full raster--and focus woulod likely be VERY bad..


YOU DEFINITELY need to check your HV PROBE !! I'll BET...from that pix...you are getting at LEAST 23KV.

I'm sorry. I did not mean to incite confusion.

The pictures posted first are of the set before the previous owner stored it. It does NOT display like this today. That is how it was. and should be...



That is what I see on it, today. After about 15 minutes of on time, focus goes, then the picture fades out.

[old_coot88]

Take a look at the two 6GU7s on the far right end of the chroma board. Are their heaters lighting?

If not, with those heaters cold, here's what's happening: the plates go 'waay positive and drive the (G1) grids of the CRT positive (since the plates are direct-coupled to the CRT grids). The CRT beam current goes into avalanche, producing exactly the symptoms you describe. And this overcurrent is extremely hard on the 3A3, flyback, and H.output tube.
Don't run the set in that condition.

Of course if the 6GU7 heaters are lighting, then the problem lies elsewhere.

If the heaters are cold, it's caused by a broken ground in one of the two ground stakes on the far right end of the chroma board. So re-flow those grounds. This problem was endemic to the CTC-12, 15, 16, 17, and 25.
Even if the 6GU7s are lighting, re-flow those grounds anyway as a matter of routine.

[bluenorm]

I have the same set (ct16) and in my case the first symptom was the lost of converging adjustments in one of the color(green) hv was check and was detected at 17 thousand top, a few days later was at 15 and the poof. chassis was removed and all the voltages coming out of electrolytic tested ok. the high voltage transformer burned. it was replaced with a nos and all problems were solved.

[bluenorm]

what old coot88 describes happen to a friend of my ct15's or 16, exactly as he stated. he discovered by pressing down the 6gu7 and later pressing the board near the ground stakes thus making ground. an easy fix.