206162Recently picked up this ctc 10 for $100, and so far it’s working pretty good aside from a few small problems.

First off when the screen lights up, it’s focusing fine until you turn the brightness past a certain point, then it drops off, the focus voltage decreases by about 1000 volts or so. I tried changing the focus rectifier tube and it made no difference.

Second, I can’t get the remote to reliably emit the ultrasonic frequencies. It’s running on the correct voltage, and I can heat the transmitter click sometimes, but it doesn’t want to reliably make the high pitch. I’m not really sure why, I cleaned all the contacts and made sure it was all good. I’m wondering if the actual transducer piece is flaky.

Any advice is appreciated thanks in advance

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Well, you know the focus voltage comes off the horizontal output tube & it's buddy the
flyback, so you gotta take all that stuff into account. Also picture tube might be weak
and they get all fuzzy when you try and make them bright as they age....
When you turn up brightness and the focus voltage goes down, does
the HV go down as well? Do you know if the picture tube is strong?
All these things come into play together.


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The early CTC10s used 2 neon bulbs in a regulator circuit for brightness control. If these 2 bulbs are present, see if they are lighting. Later 10s and CTC11s used a modified circuit that was more reliable that did not include these bulbs. There is a small electrolytic in the remote transmitter that will keep the motor from reversing for "up" functions if it is bad.

Change the 6BK4, adjust screens and drives

The early CTC10s used 2 neon bulbs in a regulator circuit for brightness control. If these 2 bulbs are present, see if they are lighting. Later 10s and CTC11s used a modified circuit that was more reliable that did not include these bulbs. There is a small electrolytic in the remote transmitter that will keep the motor from reversing for "up" functions if it is bad.

Yes they are lighting. Is this good or bad?

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Well, you know the focus voltage comes off the horizontal output tube & it's buddy the
flyback, so you gotta take all that stuff into account. Also picture tube might be weak
and they get all fuzzy when you try and make them bright as they age....
When you turn up brightness and the focus voltage goes down, does
the HV go down as well? Do you know if the picture tube is strong?
All these things come into play together.

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The picture tube shows strong emissions, it’s stronger than my other roundie which didn’t have any issues with the focus

Yes they are lighting. Is this good or bad?

If they are lighting then they are working. RCA did recommend modifying the circuit to the later design if raster blooming problems happened. Besides the 1V2 and 6BK4, make sure the 3A3 is strong.

I've sometimes had issues with new focus tubes not working well. I often swap in a 5KV capable SS diode and ditch the tube when there's focus issues.

From what I remember this set has the trio of 22m resistors in it vs the one giant 66m used in the later sets, they may have drifted up in value.

From what I remember this set has the trio of 22m resistors in it vs the one giant 66m used in the later sets, they may have drifted up in value.

Okay I’ll check those

My RCA CT-100 powers up and delivers good sound. The 15GP crt filaments light up and all tubes seem to light up w/o any obvious gaseous blue color. Trying not to pull the heavy chassis and hopefully something obvious that can be addressed top side with the cabinet top lid removed. Just a shot in the dark I know. Any suggestions?

My RCA CT-100 powers up and delivers good sound. The 15GP crt filaments light up and all tubes seem to light up w/o any obvious gaseous blue color. Trying not to pull the heavy chassis and hopefully something obvious that can be addressed top side with the cabinet top lid removed. Just a shot in the dark I know. Any suggestions?

Looks like your post got tacked on the wrong thread - better repost it as its own thread.

Regarding no raster, can you tell if the high voltage is coming on or not?

Update: haven’t done anything with the focus problem, but I was able to fix the remote. It just had a loose ground connection. The alignment seems off so I will have to adjust that but at least it’s working reliably