Sorry, didn't save the URL -was just looking for an illustration. A quick search shows lots of places, but I can't find that one again.

Thanks, I just found it. Fastener World Inc.

http://www.fastener-world.com.tw/upl...m_000359-1.jpg

Unfortunately they are Taiwanese. I was hoping it was a U.S. retailer. Looks like they have a good variety of hardware.

Sorry, I linked the wrong image.

http://www.fastener-world.com.tw/upl...m_000359-3.jpg

update - new HO tube
 

Got the replacement horiz output tube today. It doesn't look like the one that was in the set (it looks bigger). It cured the lack of size and high voltage regulation.

Even though the convergence problems and etc. aren't fixed, I couldn't resist putting the Rose parade DVD on and taking some pix.

I set up Vert size and linearity first, but they drfited over about two hours of viewing, as you can se in the test pattern pix, which I took last. Also, I had the chroma a bit high. After about an hour, I noticed that the black level seemed to have drifted upwards a bit, so I turned it down a little. However, the lack of 100% DC coupling is also apparent, so it may have been due to the changing light during the parade.

Those pictures look quite good. Just a bit more tinkering with the convergence and you will have an excellent display.

I have to dig into the convergence deeper. I plan to do some snooping with the scope to determine if some waveforms are just too low in amplitude or missing entirely.

Can someone with a CTC-5 tell me what kind of screwdriver works on the second tier of controls? I forgot to note what they are before installing the chassis. I can work the inner and outer first-tier controls with small and large screwdrivers, but I am poking around in the dark on the second tier and can't seem to find them with the small screwdriver.

Another thing I noticed on the closeups (see the 5th picture) is a variation in the hue or color balance (look at the talent's chin and upper neck). At first I thought this was a purity problem, but it only appeared in these closeup shots. Now I think it might be the burst gate picking up some of the video on the left edge, so the greenery or something is being seen by the color sync circuit.

Those coils take a pretty small screwdriver; they can be tough to find, and even tougher to keep the driver in the slot while you are making adjustments. There are wires that sometimes poke up and get in the way, too, so you may have to push them out of the way.

Thanks Bryan - definitely have encountered the wires

You're Getting There!
 

Wayne, seems the major part of the CTC5 restoration is completed, looking good! My Dad's CTC4 of 50yrs ago was my first adventure into color TV and was the first narrow-band chroma RCA made after the CT-100 based 21CT55. It used the same 21AXP22 but had at least 10 less tubes. I recall that the CTC5 was designed to eliminate some of the CTC4's worse problems but it remained narrow-band. Did RCA or any other tubed roundy maker return to the original NTSC wideband, low level chroma demodulators?

As you continue refining your CTC5's picture quality, please continue posting your screen shots in the highest resolution. I use DVD test disks to evaluate all my CTVs and compare their PQ against the highest performance modern ss CTV that can be accommodated in my tiny lab. My favorite DVDs are "Digital Video Essentials" and "Planet Earth". Obviously the goal is to get the TV being evaluated to produce the closest PQ to the "Lab-Standard" PQ and capture the comparisons with a quality digital camera in JPG format....Tom

I can't refer to the other "COLORTRACK 2000" receivers, but the CTC-133B (1985/86) is a wide :yes:band receiver, using IC's made by NEC of Japan, utilizing IQ demodulation. The CRT seems to produce better reds than some of RCA's previous models. I have a copy of this chassis, and it is a very good performer as far as color reproduction goes, but is does not produce what I would call a bright picture, perhaps due to the choice of more accurate phosphors at the expense of brightness. The only trouble I have had with it is a failed audio chip, and an open resistor on the CRT board, both easy repairs.
I have a CTC-4, CTC-5N, and CTC-7. RCA specifies "X and Z" demodulation in the deluxe CTC-5N, and subsequent chassis, which is , I believe, narrow band demodulation, although with improved circuits over the model years. All can produce excellent color pictures, within the limitations of their design, as can the CTC-5 Special, as has been demonstrated on this forum.
Kevin

Tube demodulators actually came in three flavors in terms of bandwidth. The original I/Q demods in the CT-100 were of course low level and of greatest possible bandwidth.

Demodulators that went directly to the CRT grids (like the (R-Y)/(G-Y) in the CTC-5 "Super chassis) were probably the narrowest because of needing high load resistance to get the necessary gain in a single stage. The X-Z were somewhere in between. They could not have too much bandwidth, or they would show bad color edges due to I/Q quadrature crosstalk; but they would not be so limited by the capacitive rolloff, due to having some gain in the demods and some in the matrix amplifiers.

I am quite familiar with the 80's attempt at I/Q demodulation in the RCA solid state set, as I studied it closely while looking at the possibility for widebanding at Zenith. The fact is, creating an IF that passes the chroma without introducing phase distortion of the upper sideband can be quite difficult (although surface-wave IF filters could probably be designed to do it). Unfortunately, RCA did not succeed, and the high-frequency I channel gain on that set was so low in order to hide problems that it did little to improve the chroma resolution. It could fairly be said to be present in the set for advertising purposes, but that was about it. It's too bad, because some very clever design went into the analog color chip to minimize pin count while sitll providing the required I-channel delay line. It is one of my favorites. The designers came up with an amazingly clever way to drive and sense the delay line with a single pin! However, when we put the set side by side with an equiband Zenith (which had a very simple color takeoff with a very gradual rolloff), the effect at normal viewing distance was nearly indistinguishable.

As part of this study, I determined that part of the problem with achieving good I/Q results was that the transmitter Q filter was under-specified by the NTSC. In order to completely avoid the sideband crosstalk, it should have had a trap at 910 kHz, corresponding to the sound carrier offset. then the lower Q sideband would be curtailed the same as the upper sideband. Without this feature, some encoder Q filters that met the NTSC spec still would produce significant energy at 910 kHz, and this would be visible in the I channel.

Another way to avoid this crosstalk that cannot be done in a 6 Mhz channel is to have the full upper chroma sideband available. You can do this today if you have an I/Q set with a composite or S-video input fed from a wideband source, like a DVD player. In the lab experiments I did, we went through the whole sequence of comparing direct RGB to baseband YIQ to composite YIQ, to RF modulated YIQ to determine at what points the degradation occurred.

Another thing we determined is that even proper YIQ wasn't totally artifact-free. The I channel lies along flesh tones, so edges of faces are not distorted in hue when the color along the edge consists only of I -since ther is no Q in the flesh tone to begin with. But sharp-edged objects of other colors, like yellow letters in movie titles, would develop reddish-orange edges. This could be somewhat objectionable unless you were viewing from a good distance. The comparable effect in an equiband set is a reduction in color saturation near the edge, which is less noticeable unless you have the original RGB picture to compare to.

The one thing that definitely improved with proper I/Q demodulation is a reduction in red smear and improvement of the detail in red textured objects. My opinion is that the wideband I was wasted on the 15GP22 - the picture was just too small - but on a bright, modern 27 inch tube, say, it could have been quite noticeable, if not for all the problems of doing it well.

OP/ED ends....

Wideband vs Equiband, Compared
 

Wayne, great writeup of your personal experience evaluating the original wideband, low level chroma demodulators of the original CTC2 chassis versus the narrowband, high level demodulators of the CTC4 and later chassis. You suggested that the performance improvement of the CTC2 was probably wasted on the CT-100's 15GP22 small size. Well I had an opportunity of verifying the obvious superiority of the CTC2B over the CTC4 in 1964 when I had both TVs converted to the much larger, much brighter 21FBP22s. I described the comparison in my first 21CT55 thread of Feb 28,08:

"When I bought my 21CT55 for $50 in '64, I brought it into the house after I got it working and ran it along side my Dad's old CTC4 he left me. Both had 21FBP22s so it was a good comparison of narrow bw color R-Y B-Y vs. full bw color I Q. The extension of full color into fine detail on the CTC2B was startling! Color persisted in fireworks until extinction which I never saw before. The CTC4 fireworks turned into white long before extinction. The CTC2B carried full color way into the shadows, the CTC4 went gray to black. I kept the CTC4 in the house for the kids but brought the CTC2B back to the garage workshop for further study. Ease of working on the chassis and CRT "forced" me to destroy the cabinet and configure the remains into the vertical chassis configuration I am blessed with today. That’s alright with me. I respect the original CTV restores but that’s not my thing."

I'm looking forward to view the screenshots of all the restored tubed roundys out there displaying DVD test patterns, direct or thru a good modulator. Hopefully a few will be 21CT55s............Tom

progress on convergence
 

As you may recall, I complained that the dynamic convergence controls didn't seem to have enough range. When I took a closer look at the neck hardware, I realized that you can't see the internal pole pieces in the rebuilt 21FBP22 tube. So, I took out the souvenir bad gun from the 21AXP22A rebuild attempt, and used it as a guide. The parts that are visible in the 21 FB are not quite identical, but I hoped it would be close enough. When I moved the convergence coils back to match the old gun, voila! The red and green now can be converged.

Blue horizontal is still a problem, but it now seems that there is a mechanical problem with the blue amplitude control. It's very hard to see this coil, since it's mounted on a second flange some distance behind the main control panel, but trying to align a flashlight and my eyeball, I can't see a brass screw like the other coils; and. I have not been able to find a slot by poking around with a screwdriver. Now I guess I'll have to pull the chassis to check it out. I can hope that the core will be laying inside the set, but it most likely is broken or missing.

I am more blessed!
 

I have been following the progress of my fathers ctc-5 that Wayne is restoring to life. It has been a long time since a picture was displayed on this set. I have memories of this television sitting in the norh east corner of our living room on Sacramento Blvd. in Chicago. I remember going up to the flat roof of our house with my Dad and tinkering with the in-line two dipole antenna aimed at downtown . My brother and I were not permitted to use this set . Only special weekend color shows were allowed. I did sneek turing it on when a color Cubs game was on what a treat. When my mother got close to the crt with the upright Hoover, the set had to have RCA service come out to use the magnetic ring to get the blue and green patches out. My heart felt congratulations to Wayne and all that helped him with parts and advice. One more memory is having a living room of cousins watching the movie Buss Stop and the fantastic color . Everyone was spellbound. Thank you again,I am in tears. John L.

John, you put that RCA in excellent hands! I'm really glad you didn't let it get destroyed like so many others. Great stories, too!

21FBP22 Pole Placements
 

I hope the blue-lateral control's placement in your photo was rotated for illustration purposes only? If not, something is terribly wrong! Is that the one that came with the 21AXP22? I looked thru my junk but I couldn't find one like I have on my 21FBP22. It is directly over the blue gun's lateral pole pieces as illustrated and has a rotation adjustable magnet that provides precise control without any interaction with the red and green screen locations. I hope the photos are useful.....Tom

Tom, you seem to have a different type of magnet assembly. The one in my picture is supposed to be placed as shown with one end over the internal blue pole piece. When I first got the set, I thought maybe it was accidentally shifted, but no. It is shown this way in both the RCA and SAMS manuals for the CTC-5, and is working properly in this position. I don't think there would be any difference based on changing to a 21FBP22, but there would be a difference if I had the same type of lateral magnet that you do. Steve Dichter sent me a couple of scans from different publications also showing the type I have mounted the same way mine is.

It appears that the end of the cylindrical magnet in mine is broken off, or at least an adjustment knob is broken off. It's still functional, but loose, and that is apparently why it was taped in position.

Edit - thanks for the photos with dimensions - I will compare to what I did.

My First Zenith, Sorry Wrong Thread!
 

My wife dragged it home from a garage sale in 1996 for $35. I fixed the remote and got a picture with no ant. Since I had no interest in TVs at the time it just sat disconnected in my office collecting dust. I finally fired it up on a test DVE disc thru a modulator a couple of days ago and got a bright, fine detailed picture with accurate color and near perfect focus! Well that got me interested in learning more about it.

Its a 25in Zenith System 3 made in Springfield, Missouri in April 1986. The CRT is A63AAX02X with a backward cap R sticker which makes it Japanese, right? The screen is stripped like my Sony Trinatron and probably has inline guns. When I took the back off, the CRT has NO convergence assembly like the Sony, just three purity rings stacked together! The yoke has only the usual 4 wires, so no dynamic convergence in here.? The ultor is a single conductor, so no electrodynamic convergence like the Sony Trinatron. I thought the Trnitron was hard to understand but this Zenith thing is spooky!

The plug in assemblies are noted as follows:
Video output 9-467-01
Main module 9-518
SM pwr supply 9-520-02
Tuner 175-2277-01

So what do the Zenith Gurus make of this. Its got 10yrs of main TV use, then retired for 13yrs and still produces a picture as good as any of my analog TVs with the obvious exception of the Sony PVM1334 super-fine pitch pro monitor.

This is typical of a self-converging yoke/tube design. The basic convergence is done by the yoke design. Touch-up is by tilting the yoke and adjusting permanent magnets. The in-line guns and striped screen mean the purity is not affected by vertical perturbations, so this degree of freedom is available to apply to convergence.

Wayne, thanks for your reply to my misdirected thread message.......Tom

I borrowed the tool you really need for those brass-screw coils - GC8276, which is a hollow yellow plastic tube with a protruding screwdriver blade on one end (which you don't need) and a recessed screwdriver blade inside the other end (which does the trick). Anyway, I think I have conclusively determined that the core of the H blue amplitude coil is missing, so the chassis will have to come out again. Drat!

A little update - finally got around to measuring high voltage: 19.8 to 20 kv. Since this is within 2.5% of the value on the schematic (19.5 kv), I think it's OK. :thmbsp:

Not much progress - instead of pulling the chassis to inspect the blue convergence coil, I did some playing with video sweeps, and while in the process. the set developed a horizontal instability that I can't diagnose so far. At first I thought the AGC or tuner might be involved, but I can turn AGC down to a low-contrast picture and the problem remains the same.

Anyway, the horizontal phase became jittery, and occasionally drifts out of sync entirely. I've tried tapping on things and wiggling tubes and wires, and tuning off channel and back, but haven't found anything that causes it. Also tested tubes (although I don't have subsititutes for most), and all in the sync/AGC/horizontal check OK.

Not sensitive to line voltage either. It did seem to clear up by itself for about 30 seconds after warmup when the set had been off for 10 minutes, so I may have to chase some thermal problem.

These old sets do have "personality!"

Any suggestions gratefully received...

I would consider replacing all the silver mica caps in the horizontal sync/phase/oscillator circuitry if you have not done so. Try removing each input to the phase detector and see if the oscillator becomes stable again (even if it is not being synchronized). Another possibility is a carbon resistor that has begun to behave badly. I have seen resistors give some funny symptoms.

When I get the chassis out, I will make some resistance checks.

Assuming the problem is caps, though, do you recommend replacing silver micas with silver micas, or with ceramics?

Silver micas for silver micas. I am not smart enough to figure out which ones could accept a ceramic cap. And silver micas are still readily available, and not expensive.

One other thing you should check is the grounds on the board. I have seen grounds cause all sorts of problems and the best way to cure them is hard wire the grounds to the metal chassis. Heat from the tubes and such will cause the boards to warp. Man,You have done a lot of work on that set and it looks nice.
Ed

Don't use ceramics, they drift too much with temperature. Else you'll be forever twiddling with the horiz hold knob.

Thanks - I wasn't sure if NP0 ceramics might be preferred. I'll just stick with micas.

I suspect in some applications NP0 ceramics might be OK, though the tolerances on ceramics tends to be not as tight as the silver micas. But the advice of wa2ise is best. Safer to replace a give type cap with the same type.

Well, I'm accumulating a to-do list:
Blue horizontal amplitude coil
Blue static pot
Silver mica caps

I took a look at the schematic for the blue static convergence pot - bah! It's a special - 100 ohms, with a tap at 25 ohms. I doubt I will find one. However, the red, green and blue DC pots are identical electrically and are tied in parallel - tops, bottoms, and taps -so. if the red or green happen to be sitting at a different rotation compared to the blue, I could just interchage the wiper connections and avoid the bad spot.

Waiting for some mica caps to show up in the mail - any day now, hopefully tomorrow, so I can start work on the weekend.

To do:
Blue horizontal amplitude coil
Blue static pot
Silver mica caps
Find out why the luma freq response is only 2 MHz - the manual shows 3 Mhz
See if focus control can be centered better

I think this hobby is proof of the law of conservation of difficulty :D

Here's the latest -
last weekend I pulled the chassis, but had nto time to work on it, I had it flat on the table, and tonight I turned it up to look at the bottom, and the missing core dropped out. It was somewhere all the way at the back of the chassis - I don't knoe how it could have arrived there.

Now the bad news - in trying to re-insert the core, I cracked it. The brass screw does have a slot internal to the core, so it could be driven from the rear. Apparently the threads were galled (maybe deliberately so that no one should screw it all the way in and lose it like happened here). Anyway, I'm guessing I got the screwdriver cocked and applied pressure to the ferrite, cracking it.

The pictures show
(048s) the original coil in place
(052s) Top - possible replacement? (would have to remove a lot of windings, I think)
middle - core from "possible replacement"
bottom - broken core from original

dagnab it! :sigh:

Wayne, if you will measure the length of the broken ferrite core, and the length of the protruding threaded rod, I may be able to help with a replacement core. I am assuming the material is the same as that used in horizontal width or linearity coils. I assume your coil is OK, other than the broken core? Send me an email.

Thanks jonh - email coming

And now the (slowly) continiung saga...

Thanks to John Folsom, I got a replacement coil (images attached). It doesn't look like the original due to having 2 windings for multiple uses. I decided to try using just the core and the mount with the old coil, which seems to have worked well (won't know for sure until I fire it up). First tried the core to make sure it would fit without binding. Then tried screwing the brass screw intot he old mount, but apparently the mount was damaged, so gave up and replaced the mount. As you can see, the replacement came with two different sized mounts. The smaller one fit the old coil.

I have had the mica caps for about 2 weeks, but no time to work on the set - will fix that tonight or in the coming week.

News on the DC convergence pots is not so good. The blue pot wiper is definitely got a big bad (open) spot. Also found out from looking at the wiring and verifying on the RCA schematic that it's not identical to green or red physically because it rotates the opposite way and the tap is towards the other end. Anyway, Cailube doesn't fix it, and in the process of checking all three I discovered the red DC pot has a bad spot too. Have to think some more aobut how to fix these

Wayne:

Here's something to try for the blue convergence pot. Get a 200 ohm pot (Nebraska Surplus sales has several types) and put a 50 or so ohm resistor in series with a 150 ohm resistor and connect the ends to the outside terminals on the 200 ohm pot. This will make the overall resistance 100 ohms with a centertap at the junction of the two resistors. You will have to mount it somewhere else on the chassis or perhaps you could find a pot that can replace 100 ohm section in the dual section in the set now.

Steve

Well, I've been working on the DC convergence some more. If you look at picture ...002 attached, you see the DC convergence in the earlier chassis, and in pic ...003 you see the later chassis I have where the blue lateral changed to a permanent magnet. In this case a 82 hm resistor has been added so that the circuit draws the same current. The reason is, this whole mess is the cathode resistance for the horizontal sweep output tube! The DC in the convergence coils is developed between the tap on the potentiometer and the wiper on the potentiomenter. Since I can't get tapped potentiomenters, I am going to use the circuit in pic ...004. The fixed resistors supply the tap point, and the three 250 ohm pots supply the variable voltage. Hopefully, the extra resistance won't reduce the dynamic current too much. We shall see.

The blue DC pot was open end-to-end as well as having a big bad area where the wiper is open. The resistance to ground at the cathode of the HO is supposed to be about 25 ohms, and measured 70 ohms. Maybe this is why the set has been sensitive to particular choice of HO tube.

I put the 250 ohm pots in a little open-backed plastic box, which I planned to mount just behind the cabinet back, so the shafts will protrude through the holes in the back. One oops - I forgot that the back insets into the cabinet frame, so there is no depth left to mount the circuit box. Will have to add a bracket of some kind.

Well, I got it put back together, and... it doesn't work right. Apparently too much resistance in series with the vertical convergence coils, which I was afraid of. Just for yucks, I tried reversing the convergence yoke (so the red coil is over the green gun and vice-versa). That resulted in better DC convergence (but still not enough range), plus the best DC setting put so much resistance in series that the vertical dynamic controsl have little effect.

At least the horizontal output seems to be OK, and no smoke was observed.

Well, back to the drawing board.

Oh yeah - still have to try the blue horizontal adjustment range with the new core.