Ctc-9
 

well looking good but for some oddness focus (need the focus voltage is about 4kv and it need to go lower which seems odd as that is the direction needed).

HV will bloom out if color is turned up much, and color is way too strong. I think there is a problem here so will need to check the CRT pins for bias.

If I advance color beyond 1/2 it goes all peter max on me and will bloom, HV goes away. Will have to study this a bit.

wow, checking the sams show the HV should be no more than 21kv and focus around 3-3.5. Seem I need to look a bit harder around there.

hmm those 3 22meg resistors show as 5% on the sams, I did not see any gold bands on them in the circuit. there are some other resistors in there as well. But before I go off on all that I will adj the HV down to 20kv and see how it all looks.

just fooling around with it I found that if I put a 22meg resistor between the focus pin and ground, the focus comes in nicely (at about 3.5kv) I did not check the screen voltages on the CRT, I assume the focus is done by some electrostatic deflection between the focus screen and the G2, but not sure about that. This set uses a pot that goes between two leads off the fly, maybe on side of the pot is open (low side of fly take off lead). well at least I know the CRT can focus, just need to work on the voltage.

went back a read sams, says setup HV for 23.5 so did that and focus is better, but still a the extreme end.

I have the same issue with mine(CTC-9A). I have not really tried to fix it yet. Focus all the way to one end. It's watchable but could be better.

do you recall if its fully CCW (lowest focus voltage)?

Yes I believe so. I think its around 4500V. Should be lower

yea that's the same as mine. I hope to check it out later tonight. there is a 27k resistor that is part of a voltage divider that the focus pot connects to. I dont recall checking that as I would have had to take it out of the circuit.

put it on the vectorscope, it has the standard cross hatch pattern. the vert lines have jagged edges all the way down. a few in each box. I tried another signal generator and go the same thing. Also I get the poor vert lines on the very top (hooked). It does not seem to be an issue when receiving reg programming from a DVD or conv box.

while I had it out on the bench I noted a hard to see film cap on the grid of the color killer tube to ground. a nice dipped cap, it was pretty small and had a value of .047 so I figured it prob was one of the 200v series that have tested so bad. I removed in a sure enough it was shorted at 150v. Replace with a 630v dipped cap. I have now replaced or checked every single film cap. Watch out for those 200v dipped....

Film caps-are those the "maroon drops" or similar ones, that were thought to be mostly OK until the last couple of years? My CTC-7 (a future project) looked like it is full of those.

Must be a late production 7, mine was all paper caps.

well the focus pot is fine, the 27k pot in series with the pot is fine, I did P up another resistor to one of the 22megs in the focus load resistor string to get it right at 66meg.

I need to find the jumper on the shunt tube and check it out as well.

Mine had nearly all maroon drops (dipped, like orange drops), except for a few oddballs that might have been replacements.

Maybe I was the only dope who assumed they would all be good. Anyhow, in my CTC-7 article is a series of screen shots showing how the picture improved by stages -- from horrible to watchable -- as more and more of them were replaced.

Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html

It matters how much the set was used; the CTC-9 I had is still working perfectly with all original film caps, though another VK'er now owns it. It has those same maroon drops everyone always gripes about, but it's a very low hours set. The more use, the more they seem to go bad. My guess is heat cooks them.

Maybe a good guess. I have seen a few maroon drops (on other sets) that looked well toasted. Some boards, too, around the sockets of hot-running tubes.

Phil Nelson

My Silvertone roundy had some bad drops (both maroon and orange), and may still have as I have not changed them all out yet. The worst looking were some .01 (Sprague orange type) on the video board near tubes the worst one was not only thoroughly blackened like the others, but had a large crack running along the top!

I think I had one bad orange, it was on the vert sweep board. the 200v look perfect, nice no evidence of heat, yet short.

Finally got the stupid trim off, man was that CRT dirty with black dust. Looks much better now. The Focus is not perfect but I don't know how much sharper I could get it.

I checked the shunt tube current all good there. I still need to do one last purity check and then a full convergence. The center convergence is good but the edges are way off. The Sams has a much more involved dynamic setup then later sets, so I am not in a big hurry to screw it up. I may try the normal touch up and see how it goes. The sams has you start out by centering the controls, not sure if it mentions the slugs and then it goes on about getting equal distance between lines before attempting to merge etc...

I did check the CRT and it was fine, thinking maybe the focus was due to a weak CRT but cut off and emission were very good so I don't think that is it. its a 21CYP22 colorama tube.

I noticed a 6GH8 was in the color osc socket, yet the sams and the tube chart on the set say it should be a 6EA8. the funny thing about it was there were some resistors around that tube that did not match the sams for a 9 but did match a 10 which uses a 6GH8. Not sure what that is all about. I will try a 6EA8 in that spot later.

Yes, my CTC-7 is a later (1959) model.