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  #31  
Old 06-19-2008, 11:51 PM
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Adjusting the AGC helped some. I found that now after I adjusted the agc, it will completely go away, but only if the h hold control is adjusted just right, turn it a little bit one way or the other and the problem can be made worse making the whole screen 'wavy' not just the top, while the horiz still remains in sync. The 'wavyness' still remains with the generator.

Adjusting the hv control did away with the horiz lin problem, the control was set all the way down, I adjusted it up until the linearity was right, about 1/3 of the way. I don't have an hv probe so I can't check what the hv actually is.

I also adjusted the focus control for a better picture, before I either had to choose between too dim, or up the brightness control and get a bit blurry, I always blamed it on the crt, but now the picture is way clearer.

Last edited by Adam; 09-13-2009 at 11:35 AM.
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  #32  
Old 07-02-2008, 06:10 AM
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Yesterday the color stopped working on this set again. Eventually, I got the color back by replacing the 6GH8 chroma osc. tube (even though the tube that was in there tested good.) But with the new tube I lost color sync, so I repeated the chroma oscillator alignment procedure, and it worked. Then when I put the tube shield back on the 6GH8, it lost color sync again, and I had to do the alignment over again, this time with the tube shield on, but now the color seems to work.

While I had the set apart, I replaced the horiz. AFC two-part diode, and that completely fixed the problem this set was having with the picture bending at the top. Then I figured I would also replace that selenium rectifier on the convergence board, and touch up the convergence.

Well now the convergence is good, the color is back, the horiz problems are fixed, but when the color went out a new problem also started, with sort of 'duplicate' images to the right (see the picture below - it's off of a dvd player, not the antenna), and it's the same on both a color and a b/w picture.

Last edited by Adam; 09-13-2009 at 11:35 AM.
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  #33  
Old 07-02-2008, 11:58 AM
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Strange, my 63 Philco has a similar ghosting problem that I could never solve.
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  #34  
Old 07-02-2008, 12:16 PM
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I haven't seen this mentioned...

I expect it has been discussed but haven't seen it yet:
Is it not very important that the tube shields have a very good contact to the grounding tab that contacts them at the base? I had a funny color problem that got better when the shield made better contact. I was going to put deoxit on it but just polished the area and put a light CRC coat on it. I have seen some tube shields that had a ground wire soldered to them. I think that was mostly in Japan sets.
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  #35  
Old 07-02-2008, 07:34 PM
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Suggest you find the luminance delay line and check all component values on either end, but especially resistors on the output side This could be a mis-termination of the delay line, causing a signal reflection.
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  #36  
Old 01-10-2009, 04:40 AM
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I checked those resistors around the delay line and found none to be really bad, but I replaced a few resistors that checked around 5% off or higher anyway. The only resistor that was off by more than 10% was the 6.8k before the delay line connecting to the 150v supply which was up to 8.2k. It made some improvement, but didn't completely do away with the problem.
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  #37  
Old 01-10-2009, 10:11 AM
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It's seems strange that both of our Philcos have this problem when I've never seen it on an RCA. Mine was virtually new old stock, so the components should be in good shape. Maybe someone should carefully compare the Philco to the CTC-15. They might have cut a corner somewhere.
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  #38  
Old 01-10-2009, 10:57 AM
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The more I look at the pix off these Philcos, the more I think this is a chroma problem, not luma. A long-term ring like this has to come from some narrowband or sharp cutoff circuit. Suspects could be the IF or chroma, but I'm thinking maybe a sound trap - either misadjusted, or a poor design that bites into the upper chroma sidebands.

So - you might look at the sound trap or traps (there should be at least one) and check components and adjustment in that area.

>>Do you have a DVD with color bars? I'm thinking this might show clearly on some of the color bar edges if it's in the chroma.

Also, I recall some sets had a color take-off adjustment that was supposed to have a bandpass tilt opposite to the roll-off of the IF and sound trap. It would affect discoloration on edges, which shows in some of these pix, but I don't think it would cause that very long-term ringing. I think this adjustment was only in later Zeniths, but I thought I should mention it.

>>Can you post or link to the schematic of the last IF stage and all of the color take-off and chroma?
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  #39  
Old 01-15-2009, 01:58 PM
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I think you have an issue with the sound trap. That was a weak issue on Roundie Philco sets. That and the tuner are the main difference between a Philco roundie and an RCA roundie. The Philco has very touchy adjustments and never got as good as an RCA.
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  #40  
Old 01-16-2009, 12:40 AM
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Can anyone with the Sams for both the CTC-15 and the 63 Philco take a look at the schematics to see what's different? I can't imagine it would take much to turn the Philco into a CTC-15.
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  #41  
Old 01-16-2009, 05:09 AM
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philco schematic (sams 698-4).... So far it looks the same as the ctc15 to me.

Last edited by Adam; 09-13-2009 at 11:35 AM.
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  #42  
Old 01-16-2009, 10:54 AM
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I don't have the CTC15 schematic to compare it to, but I did notice an unused high line voltage tap on the power transformer primary. It might be worth switching it to that to help things run cooler.
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  #43  
Old 01-16-2009, 04:50 PM
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I don't have a CTC-15 to compare it to either, but I see three sound trap adjustments:
A1, tune for minimum response at 41.24 Mhz, along with R19. A11, tune for minimum response at 4.5 MHz (intercarrier, demodulated result of 41.25 MHz).

Still couldn't tell you if the chroma ringing you see is the result of misadjustment or an unimprovable design flaw. The best thing would be a complete IF alignment first including the three sound trap adjustments, then see if it's any better.
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  #44  
Old 01-19-2009, 07:59 AM
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I've never attempted the IF alignment before. And while I have 2 of those sweep signal generators - neither works. It's something I definitely want to learn to do, but as I said in another thread I'm moving to the other side of the country (with all my sets and other junk) soon, and I don't want to start anything new until I'm relocated probably a little over a month from now, so the Philco will have to sit as is for a while. I'll try and get up the sams for the ctc-15 for comparison to the Philco schematic in this thread later this week.
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