was nothing done to it in those 8 months?

CTC-4s have PCB IF, sound, and parts of other stages.

changed the channel to 4 and subbed the 3rd IF tube. Not much difference, but now I can get a pretty clear b&w picture, but when I turn on the color all the interference shows up. Once I get rid of all color the interference goes away. The fine tuning knob still has only an eighth of a turn before I lose sync, but about half way through the 1/8 turn clockwise the color starts to fade but does not disappear and the overmodulation hum gets louder.

I must also note that none of the tubes are shielded. I'm sure that isnt helping my interference problem anyways. And Dave, according to the previous owners the set hasn't been powered up since last December.

...

The IF tubes and a few others are supposed to have shields....I recommend finding some shields before messing with it too much.

I must STRONGLY agree about the shields. My CTC4 is extremely fussy about some of them being grounded well OR I get weird diagonal lines or loud humming.

John H.

Roger that. Most of them are in a separate box that the set came with

It has to be something simple, since it worked 8 months ago. I'd agree with what Andy and Electronic M said.... Put the shields back. Also, I wouldn't attempt an alignment. They NEVER go out of alignment on their own, unless it's a component failure or someone in the past has been screwing around, and 9 times out of 10, it was somebody that got happy with a set of Radio Shack "diddle sticks". I was also reading some earlier posts. I wouldn't worry too much about the caps. If it was a repair tech that had it in the past, I'd assume it's been re-capped. Maybe I missed it in a prior post, but have you looked yet to verify? I also wouldn't worry too much about the tube conversion job. It looks like it was done long ago, and if it wasn't done right, those problems would have surfaced eons ago. It will be something so simple, you'll probably smack yourself on the head when you figure it out. :)

What generator setup would you be using for an alignment?

I have two very original and crispy CTC16 chassis' I must repair for a combo owner, so I will be looking at this issue for sure.

Usually the adjacent sound reject adjustment (before the first IF) and sound reject (at the third IF stages need to be dialed in first.
Not sure of a CTC4 swizzy, but start there - it could be all you need to tweak.

I can do alignments Dave, I have a full setup here and I'm only a state away from you. Just did a CTC-9 not long ago.

I'm not clear on the restoration status of this set. Did the previous owner do some minimal "make it work" repair years ago? Did he do a full restoration? Something in between?

If the original electrolytics have not been replaced -- or at least checked! -- I would not feel safe running this set for prolonged periods.

Forget alignment for the moment. TVs don't un-align themselves by sitting around. Install a full set of tube shields and see if they help.

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

The previous owner was a TV repairman. I was told he would fix the set if anything was acting up with it. He never did a full restoration, he just kept the set alive. I can see some wax caps that are still on the boards and in other places visible on the top side of the chassis.

Putting shields on the tubes helped a whole lot. There is still some interference with the color picture but not the B&W picture. Colors are off in some settings and text is difficult to make out. I used my CTC-7 for a picture comparison (hope you dont mind me riding your coattails with that panther lamp Phil! :D). Please ignore the moire effect on the 4 that isnt visible under normal vision nor is it that distorted looking. There is still some beat frequency but that's about it for interference.

Looks like you've gone from 90 to 95% there, unless you want to recap the set.

Seems like I might have to recap to ensure its longevity.

Seems like the color was up too far in those shots, but it's tough to get representational shots off the screen. Make sure you test all the tubes too, mine had a pair of 6Cl6's that tested nearly dead but it still worked.

Hey, the more panthers the better!

That picture stands up pretty nicely against the CTC-7. This set is already working so well, I'd be inclined to use a light hand with further work. Do what you think necessary to make it safe & enjoyable to play, but don't disturb things (convergence & alignment, for instance) unnecessarily.

Phil Nelson

I'm going to replace all filter caps, all electrolytics, and out of tolerance resistors. Going to sub the two 6CL6 in the color circuit to see if I get any difference in my light blue colors not really showing up.

With my CTC4 what I did was replace every wax and 'lytic cap before applying power even once. Too much irreplaceable stuff in there to risk a shorted paper cap taking it out. Then I ended up replacing a few brown dip caps (installed in the 70s I'd guess) as well.

The caps to be wary of would be PS lytics, sweep/deflection stage caps (where the unobtainium lurks), and since it is not working quite right RF/IF/color stage caps.

Subbed the two 6CL6's. Powered it up slowly. The colors are spot on now and I now have a nice picture. Still a bit of interference and small letters are hard to read. Needs some dynamic convergence, static conv is good. Set isnt drawing a lot of current. Only about 2.5 amps according to the PR57. Operating at a full 375 watts the set would draw 3.2 amps but it isnt even near that at 115 volts. I do still plan to electronically restore this set just trying to get a base-line on what Im dealing with. Ignore the Moire effects. The blue screen is turned up a bit too high in these photos.

I think you want to optimize focus, increase contrast, and reduce color level.

Amen to what Electronic M said.

Also, speaking as one who has served hard time grinding his teeth over dynamic convergence, I'd try all other adjustments & tweaks before you mess with that. And if you're convinced it's necessary, read the instructions carefully and perform the steps in order.

Regards,

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

http://www.videokarma.org/attachment...3&d=1469657021

"Ahhhhh! Patrick! The screen looks like a fishbowl and I see wavy lines everywhere!"

I looks like IF strip ringing, by either a bad tube or loose connection. I hope, it's not an alignment issue.
Is the CTC4, the only RCA set, that used the 6AZ8 tube. :scratch2:
My Knight-kit R100 receiver uses two of them.

I sure hope it isnt alignment. I'll take a look

Starting to think this may need an audio alignment. I can fine tune in a clear color picture, but the sound isnt there just the loud buzz of the modulation. When i turn the fine tuning knob to receive sound, the picture gets a lot of interference and the swirly lines show up. In other words the audio is not at the same tuning position as the clear picture signal. I suspect an audio alignment may be necessary.

Hope it's not the same issue mine has, the audio went totally kaput on it one day and I think the IF can has an open winding or something. I can twiddle any slug I want, all it does is sound like a radio not tuned to any station. Gotta dig back into that thing at some point.

Might want to check that it don't have silver mica disease.

Unfortunately this problem sounds like a bad main IF alignment, or else a fault
in an IF can, after fixing of which an alignment is needed.

Despite what some people say, every single postwar set I have has been
seriously out of alignment, even if it "worked OK". The picture quality and picture-sound tuning spot coincidence has been improved by either a tweek or
full alignment. If you tweek, only tweek one adjustment and return to original if
it does not completely fix the problem ... hoping that one big tweek and
one little one will 100% fix it is well on the road to Hell.

My TRK-12 was spot, perfect, on. If I could feed its video into a CT-100 it would produce a perfect color picture. The TT5, pretty much per spec, but a one-coil
tweek made it look better.

Is there any fine-tuning spot where the audio is loud and clear? (That would rule out silver mica disease and show that your audio section is basically OK.) On some sets where the audio has separately drifted away from the video, you can "walk" the audio alignment back into step with the video by carefully tweaking the audio adjusters while watching and listening. This is lower-risk than attempting a full-dress alignment of video and audio IFs.

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

No matter where i fine tune the audio its always got that horrible overmodulating hum (not filter cap hum). It gets louder as I turn the knob to the right.

Now that the picture loads....

I think this NEEDS to become a VK web meme! :D

Just put in an order for the filter caps. Hope to get started this weekend! :D

When working with my CTC-5 last week I noticed that all the service literature I have says between 19.5 - 22.5kV at the CRT anode. My CTC-5 is putting out exactly 20kV.

Why do I constantly see folks complaining about the CTC-5 not putting out 25kV when all the original service literature says lower than 25kV for this set is normal?

SAMS for early CTC-5 says 22.5kV
RCA Original Service Manual says 19.5kV
RCA Original Setup Manual says 20kV
SAMS for late CTC-5 says 22kV

See attached snip-its from some of that literature.

Just wondering as I have limited experience with vintage color sets.

Thanks.

The problem is not the literature for the chassis, it's the specification itself. Not only did they choose an anode supply for the 5 chassis which only provides around 20kv to the CRT, they also for some unknown reason decided to not make up for that lack of voltage by having ample current reserves. To understand why this is a detriment, see note 3 of this PDF on the 21AXP22:

https://frank.pocnet.net/sheets/137/2/21AXP22.pdf )

I say lack of voltage because the 5 is the only one that low, all other chassis (especially the earlier ones) made a full 25kv and had more than enough current in the anode supply to make a full and bright picture without trying very hard. Add this to the fact that the data sheet on the CRT even tells the engineers that less anode voltage equals less brightness, and it will always be a mystery to me why RCA chose in this one particular chassis to do what they did. I don't care to speculate why it happened, it's an issue and makes the 5 a real dog in the brightness department compared to other sets.

Add to that the fact that some chassis versions have a bass-ackwards brightness/contrast control circuit that has lots of interaction between controls, and some users were literally sending working sets to the repair shop because they could not manage to set the controls for a good watchable picture.

The 5s are the BOTB RCA color chassis in my book. If I had a nice 5 with a good 21AXP as well as my beat up 4 with a bad AXP I'd consider the 4 more worthy of the rare AXP.

Ah, I see. So it was the design of the set which produces the lower HV, thus being the least adequate to run the AXP. So the set literature is accurate and the 20kV is "normal" for a CTC-5. But that is barely enough to produce a decent picture compared to other sets of the same time period which produced around 25kV.

Very strange they did that considering the specs and notes on the CRT they were using.

I have noticed blooming and focus issues while adjusting both the brightness and contrast controls.