CTC-9 Winslow
 

I picked up a CTC-9 with excellent emissions on the original (or RCA replacement) 21CPY22. 2/3 electrolytics cans had bad ESR, so I replaced all three, along with a good amount of resistors which were 20-30% out of tolerance. I also changed out all of the maroon caps/wax paper caps that were present in the set. I randomly pulled a few and the majority had some sort of leakage.

On power up, I'm not getting any video through the set. I can get a very faint blue raster if the screen and drive are turned all the way up as well as the brightness. Green and Red are not visible. (Though there is a bit of green because of a purity issue) There isn't any sort of static on the set. Any troubleshooting ideas? I'm not sure how much troubleshooting I can do on the bench without the picture tube connected. It's a PITA to work out of the back of the cabinet.

Have you tested and/or replaced tubes?

Yeah, tubes have been tested. The only substitute I had to make was for a 12AZ7, which I used a 12AT7 I had laying around. Allegedly, they should substitute well. I had ordered a replacement which turned out to be a dud itself. Hence the substitute while I wait

Ok, then I would suggest making some voltage readings to look for any that are way out of normal. Start with the CRT cathodes and G1s. If there is a setup switch, check that it's working OK.

No setup switch unfortunately, 385V supply is a little low at 370.

G1 voltages are slightly high (though I believe the given voltages are normal operation, not max voltages)

Blue and Green cathodes are at 353V, red cathode is at 344V. (Schematic calls for 312V)

Screen voltages are lower as the Boost source is only 660V instead of 710

I injected a signal into the 1st video amplifier and was able to get a color unlocked, almost synchronized image. Horizontal and vertical sync were very finicky. Somewhere in the IF amplifier section, it's not getting through.

Unfortunatly I don't have any modulators capable of the necessary bandwidth. I may have a B&K 1077B laying around somewhere, which if I recall is able to do the 44MHz IF.

There is a hidden bumblebee in the IF section under the removable metal shield that gets leaky. Make sure you change it.

After poking around in the IF section, I noticed a few things. The picture detector was testing weirdly. Even after pulling it, it was still giving me strange readings. The sound detector checks as I would expect it to. Someone had already replaced both the picture detector and sound detector, not sure when. Pretty much any germanium diode should work right? I have a couple of 1N60s laying around.

I also found a bad ceramic C318, I think unrelated to my picture problem, but the cap was reading around 7kohms or so. Pulled it, still tested the same. I haven't seen ceramics fail like that before. Better to use a 50V or a 3kV? The 3kv is close to the original size (versus the tiny 50V), but not sure if there's a problem using that high of a voltage for such a low voltage application.

Lastly, I found that I somehow replaced R314 a 12k resistor with a 1.2k resistor. I somehow had them in the wrong drawer and didn't catch it when putting it in.

Fingers crossed when I fire it up tomorrow

About the diode, any regular signal Ge diode can work here (almost any)...
The cap, if is a decoupling, I don't see too much trouble in using higher voltage value. Only ones for tuning or coupling can be much more critical.

I installed the new components, still no dice. I'm not sure where to look or what I should be looking for. There's definitely an IF issue, there may be a tuner issue as well. I can't find any indication that the tuner is actually working. I was hoping that loosely coupling the oscillator in the tuner to my spectrum analyzer might indicate if it was running, but nothing. Any advice is appreciated

I was able to determine that the AGC was taking out the tuner and the IF stages. Still no clue as to why, I used a fixed voltage supply for troubleshooting the AGC and when I was finished, the AGC started working normally. Weird...

Either way, I now have a decent black and white colorbar, but cannot get the color to lock. I ended up changing the 3.58 ECO transformer as it was seized and I was unable to perform the Color AFC Alignment. After performing that alignment, still nothing. I can get the color sync to a dead stop on the screen, but no lock.

The oscillator is running and gives a clean sine wave. The two things I did notice:

1: The input to the burst amplifier is not as clean as pictured on the SAMS. My input looks more like the plate of the color killer (though still ~50v) A lot of noise near the floor, though still the same shape overall.

2: The burst pattern is only 10v p-p versus the 30v that the SAMS calls for. I tried swapping the burst amplifier and chroma phase detector for known working tubes with no change. The burst amplifier voltages are all within the spec.

Thoughts?

Does the color oscillator alignment have you ground the phase detector output to adjust zero beat? If so, what happens when you remove the ground? Is the oscillator unaffected, or does the frequency change?

Try putting a voltmeter on the control tube input and see what happens to the control voltage as you ground/unground the detector. See what happens to the detector output/control tube input when the detector is not grounded and you adjust the oscillator frequency very slightly off zero beat. Trace back to the phase detector and back further to see where you are losing either burst or oscillator input to the detector.

Well, sounds like a parasitic oscillation making rectification in some IF stage (so it throw a large negative voltage, to almost cutoff). But can be another things... difficult to predict, imagine or point out.

Well, the reactance coil got stuck. What I thought was the end was just a snag. Reactance adjustment has a lot more travel than I thought. The control voltage was not where it needed to be which tipped me off. I was able to get it locked in, and overall get a colorbar. It made a huge difference in the oscillator amplitude, which in turn corrected the burst amplitude.

Colors are wrong, and some of the colors look pastel, but overall there. It feels like there isn't enough chroma? I can't get some of the colors to where they need to be without messing up the other colors. Eg, to get white, the rest of the colors are wrong. The colors are easily washed out by the brightness

Attachment 206962


Yeah, hoping it doesn't come back. It hasn't so far. Time will tell

Can't see your colorbar pic. Could you post somewhere else?

Hopefully this should work better
https://flic.kr/ps/45md7a

That's messed up allright!
Do you get a good black and white image with the color turned down?
Have you checked the demodulator and color amp tubes?

If you swap the two 6CG7's or 12AZ7's, do you get a different result?

Black and white is getting through, all tubes were tested when I started working on it. I swapped the two 6CG7s, no difference. There's only one 12AZ7 in the set, and I don't have a spare

Here's some photos of what I'm seeing:
BW Colorbars https://flic.kr/p/2qv4NNR
"Perfect(tly lazy)" Convergence https://flic.kr/p/2qv4NPs

oops sorry - misread the schematic

Have to think more about the problem with the colors.

The multiple edges on the bars and multiple vertical lines on the convergence pattern look like some sort of delay line problem. Not necessarily the line itself but maybe an open component on the output termination. L16 maybe? Short it temporarily to see if it improves.

Edit: I'm looking at the SAMS, so, L16 in the SAMS.

I guess I would poke around the network that sets the phase difference between the X and Z demods.
SAMS L29, C118, C 119, R168, C5

I may need to realign parts of the chroma section. On a hunch I decided to peak the phase detector transformer by sight and was able to get the colors correct. I didn't do the whole AFC alignment originally, just the first part. Definitely will be doing the whole thing. May as well align the whole set while I'm at it. Had to readjust the tuner as the fine tuning control was maxing out. It really is starting to feel like someone has been in here messing with things.

Of interest, the RCA manual has a lot simpler ways for doing adjustments. The SAMS requires a lot more equipment to do some of the same adjustments. EG, with the demodulator adjustments, RCA has you do it by sight on the picture tube, SAMS has it done on an oscilloscope. Not sure if there's much of a difference.

Shorted L16, no luck. 1800ohm is reading 780ohm, I'll pull it and take a look at the actual resistance. In theory, the center areas of the convergence should be converged right? Just the edges are adjusted through the convergence board?

It appears DC-wise that the 1800 ohm is in parallel with a 1500 ohm resistor on the delay line input, so the 750 ohm in circuit reading may be normal, but it won't hurt to check. But also ckeck that the coil in series with the delay line input (9 ohms) isn't open.

In theory, the convergence controls should affect only the edges, correct. I think the three diodes in the convergence circuit are meant to provide the stable center. So it may be worth checking them. But note that the instructions say that center touch up may be necessary after adjusting the edges.

Just for comparison, the CTC-5 did not have diodes, and adjusting the dynamic convergence moved the edges one way and the center in the opposite direction. The null points were somewhere between the center and the edges - so adjusting the dynamics always required readjusting the DC (center).

Glad you got the colors correct. I tried to figure out what the phase offset was from the colors, but it seemed that there had to be a different offset in each demod. Glad it was a simple overall offset after all.

ehh? that weird Convergence pattern is being caused:scratch2: by the color section?

That convergence picture just does not make much sense, it's like the static convergence is way WAY off or the convergence yoke is off center mark, or there is a horizontal signal missing to the static convergence sections REF pins 6,7,8 on the convergence yoke plug, which can be checked with an o-scope ( SAMS ) , if wrong or missing, could cause really weird stuff,

I'm wondering if that convergence pattern may be some sort of artifact off of my generator. My BK 1249 doesn't do that, but the tek pattern generator seems to have multiple of the vertical lines. Either way, I'm adjusting with the BK from now on, and everything looks normal.

Either way, convergence is better, I still need to finish up everything and figure out why I can't seem to get it to converge correctly. I'll have to check the diodes, the center is definately moving. I'm hoping I just suck at convergence. It wasn't bad to do the convergence on my CTC-16, hoping it may be something simple. I will admit, the Delta gun setup makes me miss doing convergence on arcade monitors. (Something I never thought I would say)

A few other things, how warm should the flyback get? I was clocking like 150F with my thermal camera. I know these aren't prone to eat flybacks, but I'm super paranoid after my CTC-16 decided to munch on one( even while religiously monitoring my HOT current.) I'm debating on putting a fan to circulate air. I'm running on a variac at 115v.

My cathode current is currently sitting at 192mA after adjusting the horizontal linearity coil to the limit. HV maxes out at 24KV, I'm running it close to 21KV. Not sure if I should bump it up. The sine wave coil didn't appear to adjust the amplitude of the waveforms at all, it definitely changed the frequency, but waveform wise the peaks stayed relatively the same

Here's a video of it playing Charlie Brown. At least the colors are 95% of the way there
https://flic.kr/p/2qveVZZ

A few other things, I pulled the selenium rectifier to check it, all three diodes checked out. I replaced them with 4007s instead of putting the selenium back. Vertical convergence isn't bad, but for some reason the horizontal bars are WAY too thick. It's gotta be a generator thing. (I'm still seeing evidence of a ghost red image 1/8" to the right of all red images) The vertical bars are thinner than a pencil body, but the horizontal bars are as thick as a sharpie. I've had to redo the center convergence like 3 or 4 times as I do the rest of the convergence. The horizontal will not converge because the thickness of the lines is different. Red is the thickest, blue green are about equal

I've noticed a focus issue, where it's running out of range before it focuses completely. I popped open the HV cage and the 66Meg resistor stack was measuring 98Meg. I put in one of the bumblebee 66Meg resistors to hopefully solve that issue.

Still debating on a fan or not. Definately some fresh wax after running it for an hour

Flyback temperature shouldn't be that hot. Warm to the touch is what you want. Why are you running the HV that low? Most roundys usually specify 25KV. The lower you set the HV the more HV current, loading and heating the HV regulator causes in the flyback.

An additional thing you can do once you have all horizontal adjustments optimizedand bad components identified and replaced is swap the HV rectifier and or focus rectifier tubes for solid state substitutes...The SS parts don't have heaters and reduce the flyback loading a few watts which can be helpful in cases like this.

1) Glad you found the video problem in the generator.
2) In the spirit of check the worst thing first, ditto on fixing the flyback temperature before anything else
3) Regarding video - some luma ringing and a lot chroma smearing - could be sound trap misaligned, either 4.5 MHz trap if it has one, or IF misalignment. Chroma bandpass could be off as well. Good luck hunting it down.

Is the width too narrow like it looks to be? If so, don't sweat the convergence until raster size is correct.

Also, when you get to the point of considering alignment, don't do it until you see how much improvement you can get just by fine tuning.

I put in SS tubes for the focus rectifier and HV rectifier before I even fired the thing up. Too nervous about flyback issues. As for the HV, that was the "sweet spot" for the HOT current. It goes low at that point and then goes back up by a few mA. Schematic calls for HOT of 160mA on the SAMS. I'm pulling 30-40mA above that. I will say, after replacing that 66meg, my HV is a little low around 23kV at full adjustment. Adjustment calls for 23.5kV. I may repeat the whole adjustment process again for the HV.

Width is just how the player decides to play that specific video. Not sure why, probably formatted like that. It was converged with a full-width image. I'll try to fix the flyback issue first. I'll start probing around.

Finally decided to jump back on this set after awhile, another CTC-9 that I went through inspired me to finish this one.

I'm trying to do a video alignment after having to change the transformer between the 1st and 2nd video IF. Unfortunately, I'm not getting any of the expected readings off the SAMS.

Here's how I'm doing the alignment. HOT and Vertical output tube are removed, chassis is on bench. B+ has been set to 385V through a variac. Convergence assembly is disconnected.

Bias Supplies
Bias supplies are off of an RCA WG-307B and are set with a meter as follows:
-6V at point A (SAMS) or F on PW400B (RCA)
-15V at point B (SAMS) or G on PW400B (RCA)
-7V at point C (SAMS) or A on PW600 (RCA)
-7V at grid of horizontal blanking amp

Point E (SAMS) or D on PW400A (RCA) to chassis

Both -7V are sharing the same supply.

Signal Generator
Signal generator being used is an HP 8662A. Negative to chassis, positive to a floating tube shield placed halfway over the mixer/oscillator on the tuner. Telescoping shield on the M/O was slid down, hence why only halfway. Floating shield verified as not grounded.

Tuner is set to channel 4, Generator is set to 43.8 MHz, strength varied but no effect.

DMM connected through 10K resistor to point D (SAMS) or E on PW400-A (RCA)

I'm getting like 0.2V regardless of whether the generator is connected or not. Varying the coil doesn't change anything. Hopefully someone sees something out of place. I'm also wondering if I should work my way from the tuner forward using a scope to adjust each coil.