RCA CTC-15 estate sale find
 

I picked up an RCA CTC-12 console at an estate sale this morning. Its one of those big entertainment centers, and I couldn't fit it in my trunk so paid half the price and am having the guy hold it for me until the weekend when I can come up with some way of transporting it.
It has some vert size issues. The UHF dial is jammed. And the back right leg is broken off.
Also only the green gun works. I am a bit worried the CRT is bad, but I would think if that were so either it would not work at all, or the red and blue would be dim but not nonexistant as it is here. If it is bad I do have a spare 21FJP22, but it has cataracts, and the green gun on that one reads completely dead, while red and blue are strong, but the socket is loose, and I bet it just has a wire to one of the pins broken. Actually, I don't even know if this takes the 21FJP22, when I get home I'll have to see if I have the schematics to this.

Are all 3 filaments lit? If not you could tap lightly on the neck & hopefully that will put them back straight. Could just be misadjusted or some loose wires.

If its not the CRT, an all green condition can be caused by the color section, Bad B-Y R-Y vid outs, or bad screen network. I had a zenith that had only blue. CRT was good, but the screen pots were badly burned. The R-Y vid out tube was shorted. To get the three primary colors they take the R-Y and B-Y signals, and invert them to get the green. If one tube is bad you may ony get one color. I replaced that tube and the burned pots and everything was fine.

However since its green only i would lean towards screen controls or CRT.....

Thanks for the thoughts on the green only problem. I haven't really worked much on color TVs, as I really prefer tube sets so I just don't get as many as I do B&Ws. The first thing I'm going to do when I get this home is to put the CRT tester on it and see if its bad or not, I didn't even take the back off the set when I was at the sale. But it is still in the garage at the house of estate sale, I seriously think I'm going to have to rent a truck to get this thing home, I really don't want to as it is only about 2 miles from there to my apartment. But that is really too far to carry a set this big and there's no way I can get this thing to sit in my trunk, even if I take the lid off. I wish I had my 72 Impala running, I could have got it in there with the lid off.

I got this set home today. I actually had misidentifyed it, it is a CTC-15 not a 12. Anyway, I am relieved to find out that the CRT is good, all three guns, the red is a bit weaker than the other two, but still good.

First of all, try doing a greyscale setup on it. Turn all three guns completely down, flip the service switch and turn the red up until you just see a line, then blue until the line becomes magenta, then green to produce a dull white line. Flip the service switch back to normal and see if you havea B&W pic. If you had a white line but still have a green only pic, check the Y amp tubes. If you can't get a white line and the CRT is ok, check the Screen voltages on the CRT for the read and blue guns. It probably won't hurt to clean the tube sockets including the CRT socket either...

I cleaned the CRT socket already and checked for loose wires, I even tried lightly tapping the CRT neck. I just tried the service mode, no lines, no picture at all. I don't know if the switch is bad, or this is caused by the set's other problems.:confused: But basically I got not enough vert. size, combined with really weak horiz. sync., but once I did get the horiz. to sync. I saw the worst case of that wavy picture (usually caused by those stinking leaky filter caps) I have ever seen. The part of the screen which was 'pushed over' was about 3/4 of it and that whole section of the screen is green, but as it moved up, below it the screen would be b/w. I wouldn't be surprised if I changed those electrolytics, and found myself with an ordinary b/w picture, and just had a weak vert. out tube, maybe also a weak horiz. osc., and a few of those others weak in the color section as well. I'm going to go the the library and copy the schematic either tomarrow or next week (How can I have 900 folders of sams and never have the one I need).
An interesting note, I took the back off my 63 Philco color for comparison and found that the chassis was almost identical.

There is a resistor between the height & vert lin controls which tends to go open, preventing you from getting full height. While you have the chassis out for the electrolytics (most important) take a look at it.

Almost a clone
 

The Philco, except for the tuner, is identical to the CTC-15 chassis. The Philco SAMS is set 698 folder 4 if that helps.

-Steve D.

strange UHF tuner
 

I'm still immersed in my B&W Hoffman now, but I pulled the tubes on this to go test them last week. I have a B&K 500 and a TV 11, but these are both too old to test all these tubes in these color sets, so when I was driving up north I took them all with me to a store up in Berkeley that still has a B&K 707 in use. I also went and copied the sams from the public library up there.

What I noticed about this TV when I was removing the tubes, that is odd, is that the UHF tuner is not the same one listed on either the tube diagram glued to the HV cage or in the sams. The one on the tube diagram is part number KRK 112, which uses a 6DV4 (one of those nuvistors) as an RF amp. The sams shows both that tuner, and for earlier models: KRK 66, which uses the 6AF4. The tuner in there is part number KRK 120C. It uses two tubes: the 6CB6 and the 6GK5, both of which, according to my recieving tube manual, are usually used as VHF (not UHF) RF amp tubes. I know those are the tubes that it is supposed to use, as it says so on the tuner itself. I took it apart and it does appear to be a tuner of some sort. Also it is made by RCA, and does fit perfectly in there, however, by the way the wires are connected to it, I can tell it is not original and was a later addition to this set. Maybe this just a later model tuner that was put in there later, by someone who wanted to get UHF, but then it seems odd that RCA would have went from the nuvistor unit to a two-tube unit. I would think that they would have went to a real transistor unit after that, most of the UHF tuners I've seen use a transistor for an RF amp, even in the mid-late 60s. Actually the only kinds I've ever seen are either the 6AF4 units, or the transistorised ones. And I've never seen a tuner with two RF amp tubes before, VHF or UHF.

I stayed up late last night and changed the electrolytics. The picture is full size, but it is still all green. There is a little blue, but no red at all. I checked the 21FJP22 again, and all 3 guns are good. I tried the setup mode, all I get is a 3/8 inch thick green line, even with the green turned all the way down and either red or blue or both all the way up. I tried to put a color bar generator on it just to see what would happen, it was all green, but what was interesting was when I turned it to show the crossed lines, it would show me the white lines (becuase of the little blue it has), but the background which should have been black was all green. And this is with the green screen and drive controls set all the way down. The brightness control, tint control and color control have almost no effect on the picture at all.

Sounds like Haints to me...

Maybe a place to start would be measuring the voltages on the picture tube socket to be sure what's going to the 3 guns? But then I ain't no expert, better listen to them in here, not me... Frenchy

Adjusting the screen controls, the voltage there varies between 400 and 1000 volts on all 3 guns. Seems ok. An unhappy development, I tested the crt again, 3 months ago the green and blue guns read 3/4 of the way up the meter and the red 1/2, now the green and blue are the same, but the red only 1/4.


I'm still worried about my red gun, but at least I found what seems to be the problem, the grids are all off, green = 400v, blue =100v, red = 50v. They're supposed to be 160v.

Plate voltage is 300v on all guns (it says it should be 345v), I wouldn't think this is a serious problem.

I got a similar set with the 21FJP22 and the green gun filaments don't come on. I guess that's why the neck lights up too bright upon power-up but immediately go to normal glow. I am waiting on a B/K CRT tester to arrive.
I don't know how the filaments are arranged in there but from what was written I wonder if just sitting for years allows one filament to lay across another to short? If so, should I put the CRT upside down and give power before I try to use the "remove shorts" feature if the tester even shows it as a short.
Any advice? It is expected to be a good tube if I get the green filaments on because the set has been sitting since unused '73.

Adam, are you doing an immediate test of the gun strength after turn on, or letting them warm up for 5 minutes or so? The test of a good tube is if it meets the numbers after 4 minutes of warmup. My ctc-11 is definitely dim when first turned on but comes on full blast after a few minutes. I think that was a partial reason they had put a brightner on the set years ago. The more I use the set, the stronger it is when I first turn it on, so it seems when the set sits idle for quite a while it starts going back to being noticeably dimmer when first turned on. Doesn't bother me and I took the brightener off. Maybe your bottle could use some longer on-time to wake it up some more, 3 months is a long time. (I said 'bottle' so I sound more like a old pro, heh heh)
I don't think the filaments are anywhere near each other, but they can short against other parts of their particular gun though.
Frenchy

If only one of the three filaments doesnt light, that is an open circuit, not a short. The tube is bad. I have one like that, also on green.

John

I had left out what I think is an important bit of information, when I had first turned on the set, after it had sat for 3 months, there was a spark inside the crt neck, like when you hit the red button on the rejuvenator. Whatever it was is what I think may have lowered the emission of the red gun, the green and blue seem unaffected. The 1/4 way up the meter for the red is after its been on for about 5 minutes. Anyway, I have b/w sets that only register that high that produce a bright enough picture, even though the tester puts it in the "bad" area. And I have some color brighteners, too.

I think my major all green problem is caused by these funky grid voltages, seeing the green is way too high and the others too low. I checked the 2 resistors between each of the grids and the 400v supply, they were all good, it's almost never something easy to fix that'swrong with these sets.

Perhaps an answer....
 

Adam,
I'm not an especially technical type but do refer to my trusty book " Coor TV Servicing Made Easy." 1964 edition. Your CTC-15 chassis is somewhat similar to the CTC-12 so this may help.

Check #2 in the following list, this may have already been addresed.

The CTC-12: "No Color"

1. Check color killer adjustment.

2. IF THE 3.58 OSCILLATOR STOPS, THE COLOR WILL BE VERY WEAK, AND ALL AREAS THAT ARE SUPPOSED TO BE IN COLOR WILL BE GREEN, iF YOU USE THE COLOR BAR GENERATOR, ALL BARS WILL BE GREEN AND THE TINT CONTROL WILL HAVE NO EFFECT.

3. Check the bandpass stage, in the usual way, for bad tubes and wrong voltages. For shop repair, tune in a keyed color bar generator and follow the chroma signal through the various video and bandpass stages with a scope.

-Steve D.

I was just looking at the schematic and the grids are fed with the 405v tap, through the 22k plate resistors for the r-y, g-y, & b-y amps. For the green grid to be at 400v, the plate of the g-y (6gu7) amp would have to be up there too. The plate must not be drawing any current. Could that tube be bad?

Recent developments: The wire connecting the 400v to the red and blue was broken, I changed it, now green and blue are at 350v, red is at 190v. I have all 3 colors on the screen, but the color is all wrong. Tint and color controls are still completely inneffective.

Last night the crt socket got loose and would only work if I held it, so I took it off, it wasn't hard to get off (none of the wires were broken some just must have come loose). I spent about 8 hours trying to put it back on, finally what I did was to thread some solder through the pins of the base, then solder the solder to the wires, then it just pushes right on, and you use the solder to solder it back.

I tested all the tubes and replaced the bad ones a while ago. Now I had replaced the 6GU7s with 6AX8s, I happened to have them and one of those tube substitution books said it would work. Thanks for the ideas, I will check more of this out later tonight.

Working roundie!
 

Well, you can NOT substitute a 6AX8 for a 6JU7. I was looking at the voltages at the G/Y, B/Y R/Y amp tubes and they were just wacky. So I looked up the 6AX8 in the RCA tube book I have and it turns out it is not even a dual triode like the 6GU7, it's a pentode. I can't find the book I was looking at before, I do remember buying them about a year ago because I found them cheap and I remembered reading that they would exchange with 6GU7s. Anyway, I had 2 used 6GU7s and I put them in instead, and they work great.

No problem at all with not enough red, I just have the red screen control a bit higher than the others. I think also it had started reading really low due to loose wires in the tube base. I am now having problems with the socket in my color crt tester, so I can't test it to see if it went back up after I resoldered the base, but seeing it isn't a problem, I guess it doesn't matter. I only wish I had thought to glue the base to the tube when I put it back on, it works, but is loose, but then I really don't want to take it off again.

It still needs plenty work, the wire fuse for the tube heaters burned out, and I just twisted it together so I could continue to work on the set, but should replace it. The convergence needs to be done, and this will be my first attempt at doing that. And I need to change the electrolytics in the power supply/amp at the very least to get the stereo to work. And one of the legs is broken off.

I turned the set around to watch it for a while, and the picture tube got magnetized. I don't know what did it, I didn't move it in close proximity to any big speaker magnets or anything. Anyway I don't have a degaussing coil, but just read on an old post here that you can use a soldering gun, so I think I'll try that when I get home tonight.

Also, when I hook it to the dvd player, if I adjust the fine tuning to get the color right the sound buzzes, if I adjust it for the sound I only get b/w. With an antenna, and not such a strong signal, this isn't a problem. Is there something I can put between the dvd and the tv to cut the signal strength a bit (without giving me a snowy picture-I tried a few resistors and that's what happened), or am I going to have to attempt to realign the sound IF section to fix this?

Sounds like AGC overload. Try turning the AGC control down until the problem disappears. Back then you would have just set this on the strongest station. Turn the AGC up until the picture just starts to shift, or the sound goes wonky, then back it off just a little.

John

This is with the AGC already set all the way down. With the AGC all the way down, and the fine tuning set just before the color goes out, the buzzing mostly goes away, but with the AGC up just a little the color looks quite a bit better.

Oh. Well, you may have to do sound alignment. The good news is you use live sound for the source, and a VTVM. Sounds pretty easy. The factory procedure is wanting a "sound detector probe" though. I dont know whats in that one. I'll bet a regular detector probe would work. I'll dig a little deeper.

Set the AGC on your strongest signal source. You should be able to turn it up until the picture "shifts" suddenly, probably down and to the right, then just back off a little.

You could first check for a problem with the sound detector diode by checking from point "b" to ground with an ohmmeter. Should be about 10k one way and about 2.5k with the leads reversed. Bad tubes could cause it too. Anything to make the sound IF signal weak

Ok, heres a non-factory procedure from Carl Babcoke's "RCA color tv service manual". You'll need a couple bias boxes. 9v batteries and pots could suffice in a pinch probably. Bias is always negative here.

I havent attempted this in a long time. Your mileage may vary. :)

.

A loose IF tube was the cause of a lot of the trouble, and cleaning the volume control helped a bit. But I still have the AGC nearly all the way down, and there is only one exact spot on the fine tuning dial that is buzz free with good color. So I think I will give the allignment a try before I put the set back together for good.

The soldering gun degausser worked, but it took quite a few passes, and it's still a just bit greener on the very top and the bottom right.

That's one of my favorite books on color tv repair. The writer is a real straight-shooter. There was a copy on ebay the other day.

I did the convergence, and the color is really good now. What I thought was a still slightly magnatized tube was just the purity magnets misadjusted. As far as the sound allignment I only needed to go up to step #2 to fix it completely, but thanks for writing up the whole procedure. I'm might take a look around for a copy of that color tv book, my tv repair books are all b&w.

The vertical output transformer is quite noisy, I worry it might be going bad, but then there are no problems at all with vertical deflection.

Now I just have to replace that fuse wire, unstick the uhf tuner, and deal with the stereo. I have all these big tv and radio consoles, but its just what I keep finding, if I had my way, I'd rather be done once I just fix the tv and not have such a huge console, and I like working on the radios, but I have never done too well with fixing record players, they always wind up playing too slow, even after I clean the motor.

Glad you got it working! :thmbsp:

John

I tried the stereo, and it works so well, I don't think I'm going to change those electrolytics after all, it really is an excellent stereo, and there is no humming or any signs of those caps going bad. If anyone is actually looking for one of these big consoles and wants a good stereo this is it. It pulls in stations I can't get on many of my other radios with only the built in antennas, and it sounds great on both AM and FM. It will get quite loud too. The record player doesn't work at all the motor is completely dead. The uhf tuner continues to be strange, it was never made to be tuned with the knob, it sits on a fixed shaft, behind it is a set of gears which do tune the tuner, but these are not accessable from the front of the set. I tried it and it also didn't work at all, nothing but a blank raster. It is probably just hooked up wrong, like I said before, it looked to be a later addition with some goofy wiring. But I don't see much use in a tuner I can't even tune, so I might just remove it. I would have to find something that looks good to put over the hole though.

Somebody probably has the
 

rectangular hole plug that came in that set when new. It says: FOR UHF TUNER on it in a small circle but it is a rectangle like 1" wide and 1-3/4" tall.
That would be a nice alternative that would put it to original condition. It is neat to see those with no UHF.

pictures of this tv

sweet. The little hoffman on top isn't bad lookin either.

What's that TV in your avatar? Looks like a sylvania halolight or something like it.

*EDIT* -- Ah! Westinghouse, I just read you other thread. Very cool.

I sold this set on craigslist several months ago, but I think it just showed up on e-bay here: http://cgi.ebay.com/CLASSIC-RCA-VICT...QQcmdZViewItem

I'm almost positive it is the same set, notice the missing control door, and the missing thing that goes over the record player to play 45s (I kept that, if anyone here gets this they can have it). Also notice the position of the uhf knob, exactly the same, it was stuck in that position.

The guy I sold it to didn't know anything about old sets, so here goes the description of exactly what was going on with it when I sold it:

good stuff: good CRT (although the red gun is a bit weak, it is not noticeable), new electrolytics, and no bad or weak tubes

bad stuff: The top of the cabinet was scratched up, as the guy I got it from had kept another set on top after it broke, and the right rear leg was broken off. The record player doesn't turn at all, I think the motor is bad. The CRT had a loose connection at one of the pins in the socket, I removed the socket and soldered it all back, but I had been up all night trying to rethread the pins into the socket, and when I finally got them all in there, I had forgot to use any kind of glue, so the socket is loose. The uhf tuner doesn't work at all, there is some problem with the gears in there and it won't turn, it also isn't even the one that belongs with that set, and I just disconnected it entirely. The vertical height also changes slightly as the set warms up.

Oh, and it is a ctc-15, not a 12, I had thought it was a 12 when I first saw the ad for it on craigslist before I picked it up, and later when I found out it was a 15 I was unable to change the title of this thread.

I thought that set looked familiar. Its a shame the guy didn't just keep it and enjoy it. I hope it goes to someone who will take care of it. I wouldn't mind another set if it weren't that big. Roundies are disappearing around here fast.

I didn't realize it was Adam's set originally! I put a bid of $51 several days ago, but as usual, it's just a "rescue" bid and I won't rebid due to space. If nobody outbids and I get it, it's got a safe home.

Charles

I think you're going to be stuck with it, I had that set for sale for a little over 3 months before it finally sold. I tried here, tried e-bay, tried craigslist, I finally sold it on craigslist for $100 towards the end of January this year. No one around here seems to want the big combo sets.

Oh brother... you're probably right. I shouldn't get in trouble for bringing it home though... My fiance' just committed to take two obese sheep that a friend of hers doesn't have room to keep. At least she isn't taking the emu that the same same friend wants to find a home for!

Charles