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Old 04-27-2007, 09:55 PM
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1963 Philco

This is the one I bought from captainmoody and hauled all the way from Michigan. After using it for a few months the color went out and the picture started waving back and forth the way it does when the power supply filter caps start going out. It sat for about a year and I just got back to it last week. I checked all the tubes, only found a few weak IF tubes, and audio amp tube. Then I just replaced all the electrolytics and hoped for the best. Fired it up yesterday and it worked just fine.

But then I turned it on today to find I could only get a b/w picture. First I tried turning down the color killer, but it had no effect. This set originally came with orange drops, so I wasn't expecting a bad cap, I knew all the tubes were good because I just tested them. I'm not that familiar with color circuits, but I figured the problem had to be in a section that would effect all 3 colors, so I started testing resistors around the chroma bandpass amp, found a bad one, changed it, and then I had color again.

But then if I turned it off and let it sit for at least 10-15 minutes, then turned it back on, it would take a few minutes or so after the picture came up to see any color but green. But after that all 3 colors would be on consistently and the set would work fine. Then I switched the G-Y amp tube with the R-Y/ B-Y amp tube, let it sit for 30 min and turned it back on, and there was no difference, it was still all green for the first few minutes it was on. Then I pulled the chassis and resoldered the wire from the 400v supply to the R-Y / B-Y amp tube, then when I turned it on it was all green for only about 1 minute, then the other colors came in. An improvement, but something still might not be totally right.

This set uses the same chassis as the CTC-15, with Philco's own tuner, which I think is nicer than the RCA unit because it unplugs so you don't have to carry it around with the chassis when you pull it. The stereo and amp are also Philco's own design. I'm recapping it now, just as a preventitive measure. It is unusual in that it uses 3 output transformers, one feeding a center channel. The right and left each feed a single 4" speaker. While two 10" speakers (one on each side of the cabinet) are connected in series to the center channel transformer.

Last edited by Adam; 09-13-2009 at 11:37 AM.
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Old 04-27-2007, 10:07 PM
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OOOO! The much discussed Bewitched Zenith.

Nice Philco. Good to see it working.

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Old 04-27-2007, 10:10 PM
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A great set you have...plenty of character!

My RCA CTC-15 had some goofiness in the color. It would be out of sync (barberpolling) which I could make better with adjustments but it wouldn't quite go away. I found that it would improve as the set played and after about 5 minutes it would lock. Each time I used the set it would lock a little bit quicker. Finally it would stay locked all the time and, knock wood, it hasn't given any trouble for quite some time now. I don't know...moisture built up in the coils that had to be "baked out"? Hard to come up with many ways something could cure itself.
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Old 04-28-2007, 09:53 PM
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All that stuff I did yesterday that I thought fixed this, didn't. Now the only color I'm getting is green, even if I let the set warm up for a while. And it's not that the blue and red guns don't work at all, because I can get a good b/w picture, just not a color picture with anything but white and green. I also get a good red, green, and blue horizontal line when I flip the service switch. Now according to the schematic down below, the voltage at the plate of the burst amp tube should be 50v, I have 400v. Is that a misprint or is it supposed to be 50v? If it is supposed to be 50v and not 400v, I can't find any components in that area that are bad that could be causing that. Now the 6EW6 is definetly good (and I tried another one too), but if I remove the tube while the set is running, there is no difference in the picture whatsoever. And the tint control has no effect as well. Any thoughts?

Last edited by Adam; 09-13-2009 at 11:37 AM.
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Old 04-28-2007, 10:06 PM
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Try adjusting the color intensity control...if the chroma signal channel is working you will be able to vary the picture from straight black and white at the minimum of the control to a purple or green hue at the maximum.
You will need the 3.58 mhz oscillator signal to get actual colors and the burst signal to get it in sync.
If you have a scope I would check out the signal at the 3.58 mhz oscillator tube and see if a signal is being produced. Check the grid of the 3.58 mhz oscillator section and check the negative voltage against the schematic. As I remember you should have about -7 volts if the tube is oscilating.
Also check out the 6JU8 phase detector circuit if the set uses this tube.
If the 6EW6 plate voltage is high this means the tube is not drawing current...check for open components in cathode circuit and that the screen voltage is normal.
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Last edited by Chad Hauris; 04-28-2007 at 10:09 PM.
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Old 05-02-2007, 10:06 PM
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Working again.

The plate voltage at the 6EW6 is supposed to be 400v, and not 50, I checked it against another schematic and then I checked it again after the set was working (the 50v must be a misprint). The screen voltages and grid voltages were a bit low, but not by much.

The color intensity control would cause it to go from a b/w picture to a b/w and green picture.

The voltages at the 6JU8 phase detector would vary from 20 to 40. When I checked it the set would loose color sync all together and have the horiz color lines, but when I removed the meter it would go back to white and green.

Anything hooked to the 265v source tested about 30v low.

I replaced several resistors that were 10-20% off, but it made no difference.

Finally, not being able to find the source of my troubles, but pretty sure it did have to do with the color sync circuits, I hauled the scope behind the set and tested the 3.58mhz oscillator. I was getting a signal, I was trying to figure out if the frequency was right or not, then I just decided to try to hook the probe to one of the leads going to the crystal, and see what I got, then when I looked at the picture on the screen (the set not the scope) the color was back. I removed the scope probe, not working again. I tried just clipping a wire where I had the probe, and it still worked. I resoldered the crystal to the board, and that was all it needed.

A different Bewitched Zenith...

Last edited by Adam; 09-13-2009 at 11:37 AM.
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Old 05-06-2007, 01:53 AM
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Put the stereo section back in today, this one blows away the Magnavox I was working on about a month ago. The dials on this unit light up, it looks great in the dark. I tried to take a pic where it could be seen, but it didn't come out that great.

Last edited by Adam; 09-13-2009 at 11:37 AM.
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Old 05-06-2007, 11:42 AM
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Wow Adam, very nice. Seeing your Philco up and working makes me want to tackle mine again.
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Old 05-06-2007, 10:34 PM
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Quote:
Originally Posted by Adam
Finally, not being able to find the source of my troubles, but pretty sure it did have to do with the color sync circuits, I hauled the scope behind the set and tested the 3.58mhz oscillator. I was getting a signal, I was trying to figure out if the frequency was right or not, then I just decided to try to hook the probe to one of the leads going to the crystal, and see what I got, then when I looked at the picture on the screen (the set not the scope) the color was back. I removed the scope probe, not working again. I tried just clipping a wire where I had the probe, and it still worked. I resoldered the crystal to the board, and that was all it needed.
Modern scope probes have about 10pF of capacitence, so a 10pF cap to ground might be what you needed.
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Old 05-07-2007, 03:09 AM
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After working for about 2 days after I resoldered the crystal, I got the white and green picture again tonight. So I pulled the chassis and resoldered it again. I also did try a 24pf cap to ground (the closest I had to 10pf), but with the cap it had no color sync at all, then after I removed it, the re-resoldering of the crystal must have done something, as the color worked again. If the color doesn't stay this time I'll try picking up a 10pf cap. The side of the crystal that hooks to pin 3 of the 6GH8 already has a 82pf cap to ground, but it was only the other side of the crystal going to pin 1 of the 6GH8 to which hooking the scope probe fixed the color.
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Old 05-07-2007, 03:20 AM
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Have you replaced the crystal? It's not unusual for them to go intermittent. The heat from soldering could change its behavior.
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Old 05-07-2007, 03:34 AM
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I don't have any spare crystals, otherwise I would have tried changing it by now. Are replacements still available, if so where can you get them? From now on, I'm pulling them off of sets I junk, in the past year I junked at least 2 sets I knew had a good one. Are they interchangeable with newer sets, if so I can just drive around until I find one on the curb.

Another thing I just did was to exchange the slightly weak 6JH6 1st IF tube I was using (it was the best 6JH6 I could dig up), with a really good testing 6BZ6 (the schematic calls for a 6JH6). While the overall reception did improve with the better testing 6BZ6, but I doubt it had anything to do with my color problems.
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Old 05-07-2007, 01:33 PM
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I've used crystals from modern TVs with no problems. They're physically a lot smaller, so you might have to extend the wires, but they almost always work. You should be able to find one in an old VCR too.
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Old 05-08-2007, 04:12 AM
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Well today I turned the Philco on and had the white and green picture again, so I pulled the crystal off a NOS chromacolor II era Zenith board I had, put it in the Philco. I still had the green and white, then I tried exhcanging the 6GH8 (even though the one in there tested good), no difference.

Next I put 3 24pf caps in series to get 8pf to ground from pin 1 of the 6GH8 (the plate of the chroma reference oscillator control) and it worked. As soon as I disconnected the caps from ground, it ceased to work. I tried this several times over a period of about 10 minutes and it was always the same.
But like I said before with 1 24pf cap it had no color sync. With 2 24pf caps in series it was not consitent, sometimes good color, sometimes no color sync.
Next I'll pick up an 8pf cap and solder it in permanently and see what happens.

This has to be the strangest tv problem I've come across yet....
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Old 05-08-2007, 08:57 PM
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Color came right up today, didn't take any time at all or any fooling with the fine tuning for the color to come up like before even on a weak station, so I think this extra 8pf cap might have done it.


Quote:
Originally Posted by matt_s78mn
Wow Adam, very nice. Seeing your Philco up and working makes me want to tackle mine again.
What year Philco? I've seen later round color Philcos than this where Philco used their own chassis instead of duplictaing the RCA, but never seen an earlier one than this ctc-15 model. I wonder what the first Philco roundie was...
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