CTC5 Pickup!
 

My wife went to an estate sale and saw this TV and wasn't going to tell me about it. She was already out in the car when she decided to show me the picture. I thought it was a CTC-7 but its the 21CD789 Whitby! CRT doesn't look necked from the picture. Not sure if its gone to air. Doesn't matter even if the CRT is bad. Its a statement piece and really rare in the Pacific Northwest.


25$ She only had a 20 on her. We got this for 20 bucks...

Nice set the crt looks like a newer one.

I was hoping for the AXP22. I'll find out tomorrow when I go to pick this up.

Looks really good for its age it may even work

Nice set. I was given one by a fellow collector a few months ago.... problem was the neck and all its hardware were gone, along with the back and knobs, front trim was gouged badly and the finish needed redone. I liked the cabinet enough I initially really wanted to restore it then the reality of winter closing in, not enough space and me having a nicer condition CTC-5 in a cheaper cabinet made me realize my best move was to sell it on to another collector.

Nice find, can’t beat the price. Hope the CRT is good.

Congratulations. I paid $100 for my Whitby in 2013. My CT100 in 2022 cost $100 which seems to reflect a downward trend is old TV prices?

I restored the exact same set 12 years ago. it is in our living room and is used regularly. I call the CTC5 an evolutionary RCA design but can be made to work very well.

I have no clue about TV prices, but I suspect they will drop for two reasons -

People who collect old TVs do so because they were buying TVs that reminded them of the time when they were kids and the programs they used to watch on them. They're/we're now getting older and our ranks our thinning with new collectors not keeping up with attrition.

The same thing happened with reed organs and windup phonographs. Reed organs can be had for the courtesy of dragging them out of the home and I'd guess Victrolas and other makes are probably down 70 percent from their peak some 20 or more years ago.

The second reason affects us all - CRTs (particularly early color ones) have a finite life and few of them are available NOS and the ones found as installed have God knows how many hours on them. No one is reproducing them for obvious reasons and there's no suitable way around them. At least with antique radios, a bad power transformer can be bought new or scavenged from another radio, and even IF transformers can be fabricated without too much effort from new parts, and of course the tubes themselves are still plentiful and probably will be mostly forever.

John

A bit of a heavy set! Looks like this set was delivered on Christmas eve of 56! CRT was replaced in 1962. I think it was put out of service after the on off switch shorted out. Burned and the wires crumbled and pulled right out of the switch back. Shorting them out to bypass the switch.

Pulled the horizontal output and damper as I tried reforming the electrolytics. I gave it a good 30 minutes watching the current draw drop. One can was slightly warm.

At 85 volts I got sound from my B&K through the tuner to the speaker. Powered it down and installed the damper and output tube. I didn't go above 105 volts and got a green raster. Definitely needs caps all around.

So what am I missing... How do I open up the front service panel? Mine seems to be really stuck and I don't want to break it off. Can't check the horizonatal hold or screen controls until its opened!.

The set still has all RCA branded tubes, even the two 5u4's, damper and horizontal output. Low hours even after the rebuild?

Promising having such a bright green raster at only 105 line volts.

Tube doesn't look tired

Without the service data yet I 'm assuming to access the service controls(screen drive and convergance) I need to remove the trim/CRT safety glass?

Thanks!

"So what am I missing... How do I open up the front service panel? Mine seems to be really stuck and I don't want to break it off. Can't check the horizonatal hold or screen controls until its opened!."

SAMS says remove 5 push-on knobs, then remove two metal screws. (The screws are missing from mine, so I only have to remove the knobs.)

Do not pull down on the wire springs in the top of the control box - these are for releasing the safety glass.

Get SAMS and RCA literature at
https://www.earlytelevision.org/tv_s...color.html#rca

I can't even get into the control panel to remove the push on knobs. Door will not pop out.


EDIT: I asked my wife for help. She got the door popped open pushing the button and using a screwdriver.

Push down the center golf tab and with a plastic credit card insert at the top and gentle pry open. I suspect the hinges are slightly rusted and binding.

Once the door is open, you can fix the hinge pins and free it up.

So what does the crt show on a tester ?

Good question, my crt tester burned out testing a gassy tube. I'm looking now for a new one.

EDIT: I just purchased a sencore CR70.
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Matt Davala

I tested the 21AXP22A and it tested near new on all 3 guns. Looks like the power switch caught fire not too long after the CRT was replaced.

What do you guys do when you come across previous repairs that don't match schematics? Luckily for me I'm referencing both the sams and RCA CTC5N service manuals and they both match each other. I'm not sure exactly what the tech was thinking with some of these repairs.

Here are two of the previous repair botches. Only one of the waxed caps on top was replaced and it should have been a .01 and I found an early orange drop replacement of .0047! C108 on the sams

Underneath they really changed the contrast circuit. I tried to draw out what they did and compared it with the sams. Both the sams and RCA service data match. I thought the contrast control might have been replaced with a different value pot but its 500ohms like it should be.

I do plan to put the contrast control circuit back the way it should be.

Check out that power switch failure and fire! Thats a volume/brightness/on-off combo switch. The brightness and volume still work thank goodness. I have the power switch wires shorted. Any ideas how to replace just the on off switch?

I have currently recapped the entire top. Started on the underneath of the chassis this evening.

Hopefully I'll have this up and running in the not too distant future!
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Matt Davala

The resistor parallel with the cap looks like a 620 ohm but I measured 82 ohm. Not sure why they reworked the circuit and added a 25 MFD electrolytic on the wiper of the contrast pot to ground. And they grounded the other end of the pot when it should have been left floating.... A mystery.

That cap and resistor shouldn't even be there and that wire should be wrapped or soldered on a lug to pin 1 of the 12BY7.

showing the 25MFD cap mod they did

There was a recommended mod to change the CTC-5 contrast circuit to the CTC-7 version.
https://videokarma.org/showthread.ph...=ctc5+contrast

If the on/off /vc is a mallory easy to fix. Find Mallory KR8M & KR9M
I remember them in early 60's RCA. Others had repair kits but I never did them.
See hear https://www.ebay.com/p/2216531325

Manuals are like following bread crumbs. PCB's Golden Rods, supplaments
etc. Trouble is they always go MIA. Most shops didnt take the time to
keep there library up to snuff.

BTW nice catch & sweet cabinet !

73 Zeno:smoke:
LFOD !

Thanks for the info. Sure looks like they got it close to the proper ctc7 modification. They went with a 25MFD instead of a 50..

Thanks again,
Matt Davala

After a full recap I finally powered it up this afternoon. Full raster with good width and vertical. But of course I have an issue with brightness and I'm sure its that darn CTC-7 mod. Brightness is on near full at minimum and increasing it loads down the HV at max. I did verify the parts were as they should according to the mod. Even though the mod is for the contrast I assume it affects the brightness to some point. I have now 50 MFD instead of 25MFD from the wiper of the contrast to ground. The previous tech only added a 25 while the CTC 7 mod calls for 50mfd.

I'll pull the chassis again and do some measurements of the brightness circuit as well as the contrast circuit. If everything checks ok I might revert back to the stock CTC-5 contrast circuit and see what effect it has on brightness and go on troubleshooting from there.

Any other ideas? BTW agc and sync were out of wack but I'm sure thats because the video output was being driven really hard.
It also seems that DHR4863 was unable to fix his CTC-5 issue. Unfortunately it sounds exactly like my issue....
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Matt Davala

Have you followed the instructions in the service manual for setting the screens and background controls? The directions are different than those for sets that have a service switch.

Thanks for the reply. I did go through the manual and got the brightness level settled in. Interesting relationship between the background and screen controls.

Setting convergence on this thing is a pain! I accidentally pushed a coil trimmer screw for one of the convergence settings past the threads. Watching the screen and twisting I didn't realize it was at the bottom of the threads already. Got to pull the chassis for that.

No color coming through. I adjusted the killer control but saw no change to the bars. I'll see what I can tweak from the topside but I'm assuming I'll be pulling the chassis for that too.

Tuner, IF, video, audio and the deflection all seem to be working. Darn chroma!

Thanks guys,
Matt Davala

Wish I was watching this in color! Vertical hold requires about half a dozen adjustments until it warms then its stable.

The tubes in the chroma section feel pretty darn hot. I think I remember that board looking toasty. I'll check resistors there tomorrow.

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Matt Davala

my precious color! that filthy hobit stole my precious color!

https://i.ytimg.com/vi/YgmlGqxHamM/hqdefault.jpg

“Vertical hold requires about half a dozen adjustments until it warms then its stable.”

Looking at the schematic, one can see why, at some point between the CTC 11-> 15, RCA added a voltage dependent resistor into the mix, this no doubt made it more stable and robust and less susceptible to instability as the parts aged.

In my Whitby I had a lot of problems with vertical sweep. The vertical hold drift I fixed by changing resistors. I found found the original very temperature sensitive.

I'll be pulling the chassis again today and I'll replace resistors in the vertical section.

Did you have any trouble with the chroma section? Seems my 3.58 oscillator isn't running at all since there is zero color.

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Matt Davala

If it was not running, you would have the telltale greenish hues when you turn up the color, can post a pic later.

Interesting.... I figured without the crystal running I would have no color. I have good greyscale tracking but zero color. If I move the hue control there is a tiny change in the grey but that's it.

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Matt Davala

https://i.imgur.com/9HcgQcz.jpeg


This is what My CTC-16XL was like with the crystal disabled! :yes:

When the 3.58 reference signal is missing, the chroma signal cannot be demodded in phase but only in amplitude, so it's displayed as just that yukky green color. Has to do with how the signal's phase is baselined.

Yay! Or maybe not yay... I found an open 6.8k 7 watt supplying B+ to the first chroma tube. R172. Above the resistor the chassis looks rather dark. I'll ohm out the transformer that connects to the plate. What the heck caused that to get so darn hot?

EDIT: I do have continuity through the transformer to plate. I do not have a 6.8k in stock unfortunately. I miss being able to buy stuff locally.

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Matt Davala

Power to the plate of V22 1st chroma bandpass amp, that would do it!

I would expect to find more bad resistors!

I can't tell for sure from the low res pics in the sams, but it may look like the set has many paper caps, and if it does many may be bad and leaky and need replacing, if C142 is very leaky, it could very well have toasted the resistor.

I wouldn't think the ceramic cap C142 would be bad, but I have no capacitor tester. How critical is it really that I couldn't sub in a modern .01 orange drop equivalent?

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Matt Davala

If it's ceramic, then the chances are rather small that it's shorted, but not unheard of, the DO short, but it's really rare, as mentioned above, I could not see clearly what kind it really was, you will know rather soon if the new resister starts to heat up way to fast if something took it out like a short or something.

But if there are paper ones in other areas, best not to trust them.