CTC-5 Westcott restoration
 

Well I finally got one! The TV I have always wanted. The CTC-5. Traveled all the way to Massachusetts and back home to Florida. By car. It was a 19 HOUR drive! It was well worth it in my opinion. Got the set for $500 with a good rebuilt 21axp22a that tests like new on all three guns. Not to mention the cabinet is in great shape! I have already started work on this set and I have stable HV and great vertical and horizontal sync. I have recapped all boards but the chroma board which is up next. The set is already showing great potential.
I will post new work as it is done.
Here is a photo album with more pictures (will be updated as work continues) http://imgur.com/gallery/9a4Fa/new

Nice, I always liked that model. It reminds me of the CTC-7 Anderson console I had a few years ago, Ed now has it up in Buffalo.

It does look similar to the Anderson!

Sweet! This is the first antique TV I ever saw. I stumbled across Doug Harland's CTC-5 Westcott on Youtube many years ago, and I've wanted one ever since. I'm looking forward to seeing your progress on it!

The hue control won't bring me near the correct colors. Just recapped the chroma board. I remember adjusting a coil in my ctc-7 to adjust the range of color the hue control had. Is this likely the same adjustment for this set?

Cool ! I like the ctc-5 cabinet among the best of old tvs...... Nice small footprint.
Good Luck, mine is still in my storage closet..... Someday..... One winter I'm
going to have all my crap in a row and have time scheduled to work on some
of these sets.....

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That's looking really good so far! A good buy for the price!

Finished recapping the chroma board. The picture has severe purity issues. Will address that then do a preliminary convergence and get a decent b&w picture first. Then for the color. More to come later.

I can get a decent color picture but after 15 minutes I lose most of my blue screen. I know the blue gun tests awesome. Intermittent connection maybe?

Soon to have that famous Early Roundie "Glorious Lollipop Color".... (grin)

Nice tv set! I also am restoring my CTC5 Westcott, coming soon...

Monitor the blue G2 and G1 (color blue color video injection point) voltages before and during the loss of blue. The one that changes is your offender.

Here is what I have now. The picture seems like it could be a lot more brilliant. I cant turn up the color too high or I will not be able to get correct colors. Please excuse the purity issues. Could this picture be improved? It looks a bit better in person.

The luma signal (i.e., the black & white or 'video') component is absent. Only the chroma signal is being displayed.

Could the delay line be causing that?

The most frequent causes of loss of luma are 1. Dirty Service Switch (but I don't believe CTC-5 has a Service Switch) and 2. Heater-cathode short in the CRT.
Try tapping gently on the CRT neck with something like a screwdriver handle. That'll usually show up a H-K short.
Other things can cause loss of luma too, including open delay line.

Looks like I had it in my first picture of the set without the color...

I also suspect the chroma takeoff and 4.5 mc coil may have something to do with it. The crt checks fine with the H-K so I dont think it can be that.

If you have a test pattern generator with a strong variable level video output I'd use it the try injecting video to various points in the monochrome signal chain (use a cap in series with the video lead to prevent DC from damaging the unit unless you know the generator has one built in). Start at the monochrome video output (if injecting at the grid gives you video work towards the detector till you loose it otherwise work towards the CRT till you get video). If you have an audio/RF signal generator you may be able to use that in place of the video generator by finding a frequency that is a multiple of the vertical and or horizontal scan rate...I did that in a pinch once, and it worked well....So well that I ended up playing with different frequencies to see what kinds of patterns I could make. :D

If you have an oscilloscope you can trace the video forward from the detector till you loose it. Best to use a vertical bar gray-scale test pattern for the scope method since it will give you a nice easily recognizable stair stepped pattern between the sync pulses.

Will do

In your screen shot it looks like the chroma level, color sync etc. are good. So turn the color control completely all the way down. Forget about color for now. It's a completely separate system from the luma (B&W video) chain. With the color off, the set should show a normal B&W picture.
The luma chain is what you need to work on.
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On a related note, remember that in a tube type color set, luma goes into the CRT via the cathodes; color goes into the CRT via the (G1) grids.

Bad Delay line or last video amplifier. Check the delay line and the connections to it.

He is right ! check the schematic, follow where the video amp is and look
anywhere along the line, don't get stuck on some single part just cause you
know it's name, troubleshoot it along the way.... Contrast control, tube, check
tubes & tube voltages, lose parts, tube sockets, hit stuff and boards with a
nude stick see if it's intermittent, etc. etc....

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OK the 4.5mc coil was badly out of alignment so I readjusted that with my scope. I think I now have a pretty good picture for a CTC-5 super. Aside from the purity issues it looks pretty good in person. I will do edge purity and a bit of convergence since the convergence already looks good. Then I will take a look at the HOT cathode current and adjust that if needed. Also going to add a fan to the HV cage to keep the fly cool. And then I may be already done with this restoration!

Much improved! Still looks a bit washed out, though. On the video I mentioned earlier, the Westcott had a sharp, rich picture.

I did some reading up on the A version of the 21axp22. The red dag coating was used to prevent internal arcing in the neck of the tube. Does this imply that the original 21ax had arcing issues inside the neck? We're the phosphors on the A version improved over the original?

There are at least 3 flavors of 21AXP22 that I'm aware of:

The earliest ones had the same phosphors as a 15GP22 giving a greenish look to the screen and had normal grey dag on the inside, the chassis they were used with always had series anode resistance to protect the flyback in case of an arc in the CRT. Part number would be 21AXP22.

Next is the same tube, just with improved brightness from different phosphors. This one was used in most of the CTC-4's you see out there unless a replacement was installed, and it's easy to tell because the screen appears white instead of greenish. Part number is still 21AXP22, still all grey dag.

Last version to come out before the glass tubes was the 21AXP22A. This is the one with a white screen and red resistive dag on the inside, which eliminated the need for series anode resistance for arc protection from the previous model. All CTC-5's used this tube and it's compatible with earlier chassis.

The same is NOT true of putting a 21AXP22 (non-A) into a set having a CTC-5 chassis, which has no built in series anode resistance. While it's true it will 'work', the caution there is that without any series anode resistance you run the risk of shorting all HV anode current to ground in the event of a CRT failure. The whole point of series anode resistance is the protect the chassis, without it you blow up more parts when the CRT goes. So if you have a CTC-5 and your CRT has all grey dag, either install some resistance in the anode lead or prepare to replace the flyback if the tube dies.

The red dag doesn't prevent arcing, it merely saves other parts from death should an arc occur.

Checked the delay line. There were two leads coming out of one end and just one lead coming out of the other end. One of the two leads read .1 ohms and the other lead read 830 ohms. The side reading 830 ohms sounds like it could be causing the complete absence of luma. What do you folks think?

Your latest picture does not show complete absence of luma, although it does look like the brightness control is way too high, washing out the blacks. Do you have the service manual that gives the CRT bias setup procedure?

Regarding your delay line resistance readings, are you measuring in-circuit or out? And exactly where are you connecting the ohmmeter?

The service manual I am reading is the one from the ETF website. I am reading the early set manual. I dont see anything that specifically says CRT bias setup. And I tested the delay line in circuit. I was measuring everything from the end with only one lead on the delay line.

CTC-5 CRT setup procedure
 

See the setup procedure attached.

Regarding the resistance readings of the delay line in circuit, it is very complicated to tell what they should be because you are measuring everything connected to it. The only way to be sure is to have readings from a good set to compare to.

The alternative is to disconnect the line and see what readings you get of the line by itself. There should be conduction from the input to the output and no conduction from either the input or output to ground.

I'm not sure what the normal resistance is between input and output, but I suspect it will be low, as theoretically the line is supposed to work by a combination of distributed inductance (the coil) and distributed capacitance (the coil is wound on a thin insulator over a ground foil).

Possibly a reasonable test would be to simply by-pass the delay line and observe if contrast is greatly improved? : :scratch2:

Of course the picture would be a little strange looking, as the luminance signal would be slightly ahead of the color signal, but it should give you an indication of the operation of the delay line.

jr

How would I replace the delay line if it might be bad? The setup procedures did not seem to do anything. Maybe something in the contrast circuit could be bad?

Starting to think that the delay line is not the issue here. I can get an OK crisp picture but only with the contrast, color,and brightness turned down pretty far. Only watchable in a dark room. I checked two of the pins on the 12BY7A video output tube (plate and screen grid) and found that both voltages on the pins are off. This must be an issue with a resistor in the 12BY7A portion of the board. I must note I wired in parallel two 1 uf film caps to create a 2uf cap to replace the electrolytic that was there. The schematic calls for a 2 uf cap but the one I removed was an 8 uf. I never found any production changes stating that a 8 uf should be used instead of a 2 uf. Maybe I should try an 8 uf?

If it's any consolation, I have never been satisfied with the luma drive level on my CTC-5. It seems the chroma sections have much more capability. It's on my "some day" list to revisit this issue, but now that it's been brought up, maybe someone else here can comment.

One thought: check the AGC and make sure you have the proper video level at the video detector. Also try substituting video output tubes. In the Magnavox set I had, I found that the output tubes varied quite a bit and you could get more gain out of some than others. I think the luma channel is really pushing to get enough gain out of the final tube.

perhaps a contrast mod would be wise?

I think it couldn't hurt. Just be careful and don't get the control reversed like I did. It works OK if you do, but max contrast is counterclockwise.

Did you wire the pot up like in a ctc7 or ctc9 or perhaps a different type of mod? Add another video stage, perhaps? :scratch2:

jr

Here's the mod. I posted it in 2008, but it looks like it has disappeared.

Thanks for posting! I guess it looks more like the early ctc7 circuit versions, with the 3900pf cap. The text appears to be correct, but the schematic appears to not show the ground connection for the cold end of the pot/- of the cap/1k resistor.

jr