Doesn't this set need to be registered in the ETF's database of surviving CTC-4's?

That's why it's the runt of the litter, so to speak. For the same reason I, like Tom said, would cannibalize a 5 to get a CRT for a more deserving set. Done it many times. About the only ones that don't fall into that category for me are the more rare Deluxe doored models like yours, my Wingate and maybe a few others. But apart from that, they fall into the category of donors.

Here's a thread talking about the circuit mods, BTW.

http://www.videokarma.org/showthread...=256638&page=2

Thanks very much!!!

Pulled the chassis tonight. Multiple repairs have been done. You can tell it was owned by a repairman. I have already started recapping the filter caps. More to come later.

It's amazing what a bit of tarni-shield and elbow grease can do! :D

Reading the nth explanation of the 5, got me thinking:

1) Did the DeLuxe, with its better color, video, and sound circuits, have the same low HV as the Super? If so, that's a shame.

2) If you consider the 5 as a donor anyway, how about the possibility of rebuilding the HV section based on a better design. Maybe the main replacement needed would be only the fly, with the same yoke? Or maybe you'd need both? If this makes sense, I'd be tempted to try it on my 5, which makes me cry because it's got a good CRT being shown to such poor advantage.

Wayne,


This is a problem with all 5 chassis, including the Deluxe ones unfortunately. The problem is the flyback, it's got a lot more primary resistance than other models. This means there's a practical limit to how much current the HOT is able to sink, which in turn limits how much HV can be made in the secondary (lower current primary pulses means lower amplitude flyback rectification in turn). I'm not sure why this was done, but it appears to be in the design and intentional. Perhaps the engineers wanted it to be 'safer' or something, we'll likely never know.

I have a few different flybacks I can try in my Wingate (CTC-4, CTC-28, CTC-15), but the problem is not getting more HV or a yoke inductance match from the swap- there are ways around both those problems. It's getting all the ancillary circuits to play well with the new transformer that's a big question. None of the tertiary windings that provide pulses to circuits like burst gating or AGC appear to be common across chassis to me, which makes the job of adapting them much harder. Some flybacks had positive going pulses, some negative. Some had very high amplitude AGC, some not. What I see is probably a matching/inverting network and possibly some slight phase shifting to make the new fly work. It won't be a plug in deal unfortunately.


BUT- the payoff would be a very nice chassis indeed. The deluxe sets had good circuits in them for color processing, they just had a wimpy horizontal output transformer. I'm going to give it a shot at some point, and I'm also going to try primary side pulse style HV regulation. It'll be like reengineering a complete section of the chassis.

Still have 2 more filter caps to replace, but I thought I'd do a power up to see where I'm at. Current draw is about 2.5A and only putting out about 3 KV. I don't believe the HV readings since the yoke is not plugged in and all I'm using is a piece of wire to short the yoke connection so the HV will actually come up. Found a 80 uf in place of a 40 uf in one of the filter caps and most of the hacked in filter cap replacements had shot their crystallized goo out the side already. Things are going well! :thmbsp:

Personally I'd pull the H output tube, till the recap is done and the osc. has been dialed in with a scope. Don't want to risk your flyback. On my 4 I did it that way, and when I was ready to install the tube I had it set up to dip the cathode current using the linearity/efficiency slug as soon as I had HV....I pretty much confirmed I had decent sweep and HV then immediately dipped the current. If something is wrong and the fly is being fed too much current, you don't want to run it that way long....We refer to flys for early sets like this as unobtainium for a reason!

Amen to that! Only had it running 2 minutes. Still a bad idea on my part. I already heard john h's horror story with the flyback in his 4.

Replaced the seleniums with 1n4007s. Did a 30 second power up. Once the relay to turn on the HV switched on I blew the 4.5 A fuse. I double checked the polarity of the diodes and they are correct. Im thinking I may need to add a dropping resistor.

If it's a B+ relay, you need to short across it to form the capacitors initially. The inrush current is what made the fuse pop, if you find it a repeated problem add an NTC to the line.

Or I might just delete it completely. Sure soft start is good, but it's not going to be used that much to the point when soft start may be needed.

so I shorted out the relay to simulate having no B+ relay at all. Also I switched the polarity of the silicon diodes to the band end facing towards positive. I powered it up and no action whatsoever. No pilot light no tube filaments. But the HOT damper and I think the shunt regulator tube filaments are glowing. I think the diode polarity is wrong, or i killed the filament winding on the power transformer.

There are two "fuses" in the filament circuits that are actually pieces of fine wire (30 gauge maybe?). Check those; one or both may have blown.

Y leg of the filament supply had a blown wire fuse. Temporarily twisted it together for a power up. Filaments are back and HV is back and strong. Filter cap recap finished. Might be ready to shove the chassis back in and see what the CRT has to say. Still tests wacky on 6.3 but springs to life at 7v.

Well if the tube is dim and won't focus well at 6.3V you could always try boosting to 7V later.

Here are some shots after the filter caps were replaced. Produces a crystal clear B&W picture, but color isnt looking good. Have to pretty much turn the color knob all the way up to get any color, but the hue is all wrong which I contribute to purity issues since the set is in a different position than the one it was in the last time it was powered up. Still have that pesky interference that comes in when the color is turned on. And it looks like the element on the electron gun is a bit discolored so that may explain why this tube is a bit weak at 6v. Everything is going well so far. Now I need to do a full recap.

Ive noticed that this crystal in the color circuit rattles when I tap on it. This doesnt seem right.... Might need to buy a replacement. This might contribute to the incorrect colors.

If the oscillator doesn't quit when you tap on the crystal, it's still OK. Just stop tapping on it in case you might break it.

Well Hopefully the chroma issues will clear up once I do a recap. I really hope I dont need to do an alignment. Put the chassis back on the bench and I'm going to order a full set of caps soon. Hope to get this working before the Christmas holiday season.

Work has Begun!
 

Replaced about 15 of the paper caps so far. Probably going to have to fix my filter cap arrangement, kinda sloppy. The recap of the paper caps is coming along nicely. Most of them seem to be original caps. Bet I could sell these two bumblebombs for a pretty penny to the audiofools.:naughty: More to come later.

I have noticed something strange. I was trying to figure out if my chassis is a early or late production chassis. Reading Bob G's article on CTC-4 chassis variants determined that my chassis was an early production chassis. One thing I have noticed is that the RCA service manuals and schematics calls for a 3.58 MC oscillator crystal, but the sams calls for a 3.579545 which is extremely close to 3.58 Mhz. This crystal seems to be a factory original part of the set, but I am confused as to why there isnt a 3.58. Maybe RCA ran out of 3.58's and used 3.579545 to substitute. I must also mention that the crystal in the set rattles when I lightly tap on it.

The difference is because of a mathematical practice called Rounding....In many engineering disciplines (including electrical engineering) rounding to 3 digits is common practice.

One drawing just has an unnecessary number of sig figs.

3.58 is simply the rounded-off figure. "Three fifty-eight crystal" or 'color crystal' is all the same thing.

If the oscillator uses the crystal alone as a series resonant element, the crystal is tuned to be series resonant (a short circuit) at 3579545 Hz. However, nearly all chroma oscillators use a crystal in a "parallel resonant" mode. I put "parallel resonant" in quotes because the crystal is not tuned to be parallel resonant in itself, but to be inductive, so it can be either series resonant or parallel resonant when combined with a small amount of capacitance (consisting of both strays and discrete separate parts). In this mode, the crystal acts as a very large inductor resonating with a small capacitance, and the combination is resonant at 3579545 Hz. The crystal series resonance in itself is then a few hundred Hz different from the correct frequency. Common values for the total tuning capacitance would be in the range of 20-30 picofarads. The value of capacitance for which the crystal is tuned is specified in a manufacturer's part drawing, but not in service literature. Generally, crystals made for different values of capacitance can be substituted because in most cases the oscillator center frequency can still be tuned to the correct value; however, the pull-in range and hence the temperature drift will be different than intended.

Might have to replace the crystal. It rattles when barely tapped. And as I was recapping I accidentally hit it with my pliers.

I would suspend judgement on the 3.58-Mhz crystal until you finish recapping and try the TV again. If the crystal is bad, the telltale signs should be pretty obvious, as I observed when working (and working and working) on my poor old CTC-4. It will be easier to diagnose that after you eliminate bad caps from the color circuits.

If you do eventually find that your crystal is bad, I can send you a spare from my stash.

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

Good Idea Phil. Better to narrow it down first. It was working last time I powered it up since the color oscillator was in fact running at the correct frequency. I really appreciate your offer to send me a crystal if the need may arise. Thanks!

Only have about 7 more paper caps to replace. Some values Im going to have to order. Going to do a power up later this week. Found one of those El-shitco caps that the ceramic case had cracked and the inside was almost hollow... wow.

Fixed the previous issue. I have a few more paper caps to replace which are values I didn't have on hand. Did a power to see where I'm at. Still pretty much the same when the old caps were still here. Didn't expect recapping to do much since that's not how it usually works.

Here is what I got. As you can see I have a nice black and white picture. But the color is a different story. There seems to be an absence of yellow and any purple colors. Rotating the Hue didnt do much and this was the best I could get it. I also have to turn up the color control about 3/4 of the way up to really get any color. And you can see i have that slow horizontal bending that almost looks like bad filters (all were replaced)when straight lines show up on the screen. I almost suspect that the crystal oscillator is actually bad.

Have you checked the tubes recently for Heater-Cathode/Heater-anything shorts...That could be introducing your hum bar.

On my set I had to adjust one of the transformers in the color demodulator....The one that controls the phase angles that the 2 demods operate on....It has an above chassis and a below chassis adjustment on it's can...You have to adjust both at once with color bars on screen, and you have to use 2 plastic flat edge alignment tools (metal screw drivers will make your adjustments shift as soon as you remove the drivers from the can)....I had to make my 'alignment tools' out of ruined mechanical pencils. I wish I could tell you which can it is, but it has been ~4 years since I did that work.
http://videokarma.org/showthread.php...Seville&page=4

You appear to have horizontal sync problems. Since this could affect color burst gating, you should probably fix the sync first. Those wigglies could come from poor sync separation, a problem with the horizontal AFC, or even a bad signal level due to AGC problems or wrong AGC setting - suggest you hunt down the horizontal trouble, and check the burst gating before tackling color. The color oscillator is probably OK, since you have stable (but wrong) colors.

To clarify: I would try the simplest things first - try adjusting the AGC to see if it makes any improvement.

Amen to Wayne's advice to look at simpler causes before you mess with color circuits/adjustments. To quote various old manuals, make sure you have a perfect (well, darned good and stable) black and white picture before you tackle color stuff.

If your 3.58-Mhz oscillator wasn't working, you'd more likely have rolling "rainbow" bands of color, not stable bars, as I learned in struggling with my sad old CTC-4.

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

http://antiqueradio.org/art/RCACTC-4...utsPhased3.jpg

http://antiqueradio.org/art/RCACTC-4...gColorBars.jpg

Now that I think about it. I had this problem with my pensbury. A 68k resistor went off value and caused the horizontal sway. Hopefully its just an AGC adjustment on this set.

Finished recapping (finally). I have to say some spots were very hard to work at, the convergence module being the most difficult. Overall recapping this set was relatively stressful to the fact I was working around fragile coils and try not to drip any solder on anything. I also made sure to check all my connections with my Ohmeter. I decided to give it the shrink wrap treatment since this set is a hard to find set and neatness is a must. I have yet to fire it up and quite frankly im a bit scared to do so since Im worried I might have accidentally broken a coil or a coil in the convergence module, while I don't recall messing up too bad anywhere (with the exception of 2 or 3 solder dropping mishaps) I'm still scared out of my mind about powering it up since this set is relatively rare. I hope the power up goes well! :sigh:

Did a power up and all went smoothly thank God! Still have the same problem, superior black and white picture but piss poor color. Still got that pesky interference. Adjusting the AGC control helped a little with the interference. It is also becoming increasing evident that the red gun is pretty weak, and its impossible to do a color temperature set up according to the service manual. What really puzzles me is the absence of all other colors pretty much except for blue and red on the color bars. I adjusting the hue coil (T125) for about half a turn and realized that wasnt it so I returned it back to its original position. adjusting the hue control really doesnt make much difference. The red and blue bars stay there until about a full turn ccw when they shift to maybe a purple color. Also i must not I have to turn the color control to pretty much the max color setting to really get any sort of a chroma signal. This further backs up the statement that replacing capacitors on antique tv or radio doesnt always magically fix everything. Any ideas on what is wrong here and any possible adjustments i can do?

One thing you should do is degauss it and perform a purity adjustment.

A note the coil that changes the hue and relative demodulation of the different bars has 2 slugs one bottom and one top (should be flat edge blade adjustments)...On that coil you want to adjust both simultaneously with plastic adjustment tools (metal ones will skew the adjustment once removed).