What causes this? RCA ctc 17 ad x
 

It's like it loses power, rolls, then comes back nice and strong

... where to start with this monster, the fact that it works means I don't want to ruin it.

Also, do I have to make a tool that discharges the crt when I finally get brave enough to pull it?


Edit: The more I think about it, and try to figure out what to study about it, the more I wonder if this is directly related to amplifying the video signal. Perhaps the video amp tube is going bad; or the circuit itself is just old, I had a tube pop and flash a few times before I replaced it. But the greenish 1/2 cast/shadowed pic (and sometimes rolling) will still come back. That said, after the set is on for a good bit it does usually stop.

Or, is it in the tuner/mixer/amp stage, I wonder if the incoming signal (from a dvd/vhs/dvr with digital tuner) is getting messed up then returns to normal. Again, most of the tubes are unaltered by me, just a few here and there as I mess around. Haven't touched the chassis components.

Or, could the high voltage be the culprit...

It looks like itst just out of focus. CRT string & so is pix.
See if it looks better with the brightness lower.
Check regulator, focus & HV rectifier tubes.

\73 Zeno:smoke:
LFOD !

It's a cataract, pre-removal, is that what you are referring to? Otherwise I wouldn't know how to tell if it is or isn't a focus issue. The image loses half its color/clarity at some points, then once on for a while only dips out infrequently

Pops and flashes doesn't sound like a cataract issue, I'd say it's a HV flashover

Try tapping on the 12BY7 video output tube and see if that affects it.

Will do now and see

Nope not really, back to the drawing board. I'll study up on the HV rect/reg and output circuits. I have a helpful book on color tv circuits, and color tv troubleshooting book, both of the same vintage as this tv.

IT does look like a cataract but different.
HINT: To make a good color TV first you need a good B&W TV.
For now turn the color down so it wont distract you. See if you can
catch it acting up on video & put on U-tube. A pix worth 1 Kilowords !

73 Zeno:smoke:
LFOD !

What's funny is this area of the chassis doesn't always make popping sounds, but I generally hear it in this area

Turn lights out to spot arcing. You cant see it in the cage while running.
Look at the HV rect socket & focus tube socket for crud & corrosion.
If you get the humidity high in the room it will arc more. We used to
open the doors in the shop to smoke arcs out.

73 Zeno:smoke:
LFOD !

you may be temporarily losing the lower half of your voltage divider chain, the lower side of the huge 18 watt or so resistor.

I find it quite odd that when it drops out, that it looks like you lose the chroma osc part of the color circuit, all green looking, those are driven off the lowest branch, at least it is on my CTC-16, and that cant be much different from the 17.

if you are losing that below that big resistor temporarily, which is a VERY common problem, it can do all sorts of strange things.

https://youtu.be/Bw5DcpmffQg

Example- it's Biden's state of the union, not meant to be political just what I had on at the time.

try again :(


Video unavailable
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Settings are wrong :/

no one can see it :O

Fixed

A good start, would be as I mentioned, when the chassis is pulled is to thoroughly check the voltage divider tree from end to end, looking for degraded solder connections on the high power resistors, the resistors themselves DO sometimes go bad, but more often then not, the solder points to the lugs degrade go bad and corrode.

Try swapping the two 6HZ6 demodulator tubes with each other, and the two 6GU7 tubes and see if the symptoms change. I'm not sure if the color goes off completely, or you're just losing red.