RCA CTC-5 Deluxe Chandler Restoration

[etype2]

Here is a link to the progress thus far.

https://visions4netjournal.com/vinta...-tv-page-twoa/

I wonder who the gentleman from California was?

[Penthode]

I like the CTC5 Deluxe. Next to the the CT100 and 21CT5, it was the last RCA Color TV with more than 500kHz chroma bandwidth for many years. It has two stages of audio IF for better quality sound. It misses the simplicity of B&W setup and convergence of later sets but it can be a good performer.

[old_tv_nut]

Originally Posted by Penthode

... it was the last RCA Color TV with more than 500kHz chroma bandwidth for many years...

Interesting. I would have expected it and all the following sets with X/Z demods to have about the same chroma bandwidth.

[Penthode]

Originally Posted by old_tv_nut

Interesting. I would have expected it and all the following sets with X/Z demods to have about the same chroma bandwidth.

If you look at the chroma section in the Deluxe chroma demodulator design, the lower chroma sideband response extends to about 1MHz. This means that there should be a degree of quadrature crosstalk but providing more resolution in the I vector direction.

I recall a 1955 issue of the RCA Review I read decades ago, long before I had a chance to examine the CTC5 chassis. I recall they did a study allowing a degree of quadrature crosstalk and I wonder if the Deluxe chassis was an attempt to justify the addition chroma resolution at the expense of the crosstalk?

Interestingly, subsequent RCA sets stuck with the 500kHz chroma response.

[Username1]

.


Light that sucker up right now, see what it does as is......
Maybe there's still an old Ed Sullivan Show stuck in the tubes & needs to get out....


.

[old_tv_nut]

Thanks.
If i recall correctly, much later Zenith solid state sets used a simplified color bandpass that consisted mainly of a compensation circuit for the IF rolloff, with a not very sharp lower edge cutoff that allowed decent color resolution with some quadrature distortion.
Designs that try too hard to get max bandwidth with no quadrature distortion will suffer from ringing chroma transients, which can get worse than the quadrature crosstalk if the cutoff is really sharp.

[old_tv_nut]

By the way, if the response is significant in the lower chroma sideband, I would expect the DeLuxe to have more cross-color than subsequent sets.
Once it's restored, it would be interesting to compare the effect in the Indianhead resolution wedge to a Super or a later RCA. Come to think of it, I've never looked at this in a CT-100 - would be interesting.

[etype2]

May 6, 2024, day one.
Restoration begins.
Mike Doyle came by today to pick up the CTC-5 chassis and take it to his shop. He will jig the chassis to a test color CRT. He needs to finish a Korean prewar radio and after, will restore his own personal CTC-5. After that he will start on my CTC-5, the subject of this post. Mike has restored two other CTC-5’s prior to this project and is familiar with the circuit design and layout.


Below, a few pictures of the disassembly.

Photo #1 RCA added printed circuits with this model and looks to be original.

Photo #4 6X8 tube missing from tuner assembly.

Photo #6 RCA Monogram factory rebuilt 21AXP22, serial # CC11949.

Photo #7 Emissions test of CTC5U chassis.

Photo #8 All three guns test very good.

Photo #9 Life test reduces filament voltage by 10% and no change in very good to excellent readings.

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This link will take you to my website page. https://visions4netjournal.com/vinta...-tv-page-twoa/

[etype2]

May 24, 2024

Today, we moved the CTC-5 cabinet and CRT into our home theater room, awaiting the restored chassis from Mike. I do not plan on restoring the cabinet. It’s in remarkable condition with only a few nicks and fingernail damage around the channel selector.

Full res,
https://visions4netjournal.com/wp-co.../IMG_4739.jpeg

[Penthode]

My CTC5N chassis Whitby is almost identical to yours. In mine I am beginning to see the defocussed silvering highlights the CRT and it appears the CRT has had its day. Certainly under test, the gun emissions are not balanced and Red is dropping off. I am weighing the merits of using a "Britener" to boost the filament voltage.

I tried testing the tube with increased filament voltage and emission picked up on Red. But the guns do not appear to track well.

I would be curious to hear experiences with others aging CRT performance.

[etype2]

We have not been able to achieve the same level of color fidelity as the Westinghouse H840CK15 with our RCA 21CT55. Our CTC-7 has a brighter more saturated image, but not as accurate as the H840CK15. I’ve never seen a live CTC-5 image, only in photos. It should be interesting if nothing catastrophic is found in this restoration.

[dtvmcdonald]

Originally Posted by etype2

We have not been able to achieve the same level of color fidelity as the Westinghouse H840CK15 with our RCA 21CT55. Our CTC-7 has a brighter more saturated image, but not as accurate as the H840CK15. I’ve never seen a live CTC-5 image, only in photos. It should be interesting if nothing catastrophic is found in this restoration.

I've seen the deluxe CTC5 at the ETF after I got it displaying a picture
off my own DVD/Blonder-Tongue. Its abysmal due to bad RF/IF tuning.

But on my own test patterns with only large color areas the colors are just fine.
I was unable to attend this year's convention where I was going to align it.
Next year.

[etype2]

July 25, 2024

It’s on the bench.

The “official” start of restoration begins.

From Mike,

It is on the bench. I will be connecting crt wires back to where they need to be and I will install the volume/on/off brightness control with a new switch unit. I will install missing tubes and fire it up to see “what we have got” for the beginning of restoration.

Here we gooooooo!!!

Mike

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[etype2]

July 28, 2024 Day 84

Volume/Brightness control rebuild

From Mike,

The chassis came to me with no brightness/volume/switch control.# That part was a bunch of broken pieces.# I had a control assembly in my parts pile, but in checking it out, the switch was bad and the 1 megohm volume control pot was "open circuit"# The part number for this piece is RCA 102156 which, as far as I can tell is un-obtainable.# If this chassis is going to work again, the control that I have here would need to be re-built.# A very delicate operation.# The problem was the brass rivets that contact the wire lugs to the carbon path of the pot were loose.# So, I had to try something that I have never tried before, and apparently, it worked.

Pix 1# Volume/Brightness/switch loose wires and damaged parts from the original assembly.
Pix. 2,3,4 My control with issues like open 1 meg volume control and bad switch.

Pix.# 5# Pieces retrieved from broken assembly.# These had some usable parts that I used in the re-build process.

Pix. 6 Disassembled for repair.

Pix 7. I started by drilling with a pin vise by hand to remove the brass rivets, but the rivet started rotating so I switched the tooling to Dremel tools. This worked well.

Pix. 8. The repair is a success showing the 1 Meg reading on the ohm meter.

Pix. 9,10.# Details of the #2/56 screws that replaced the rivets that I removed.

Pix. 11.# Control re-assembled and ready to install including the new switch unit.

Next, is to install this unit and then figure out the connections for the crt wires and get them hooked up.# Then, it is time to fire it up and see what we have got.

Cheers,# Mike

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Stay Tuned.

[etype2]

NEXT

The crt wires have been reconnected to the proper points. No tubes have been tested and several of the tubes are missing. I will install missing tubes tomorrow and hook up to the jig. It is time to "see what we have got" before any further restoration procedures. The next 4 pictures are as follows.

Pix 1 Chassis top view before preliminary cleaning with vacuum and brush.
Pix 2 Chassis after vacuum and brush cleaning. More cleaning will take place as the restoration continues.
Pix. 3 and 4. The newly rebuilt control mounted and wired.

More to follow.

Mike


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