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Old 10-21-2017, 09:18 PM
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CTC-5 Lost Vertical Deflection

Calling the CTC-5 Guru's!

Well, first, it's been way too long since I logged into VK. Nothing personal! Just been working on other things. About time I (tried) to fix something.

I hadn't fired up my Whitby in almost a year. The last time I ran it the convergence looked terrible & since I finally cleaned the stack of other sets off the top of it, I could pull it away from the wall. It powered up without drama (which has not always been the case with this set) and it ran for about 30 seconds before the vertical collapsed. Now, I really am not in a hurry to pull the chassis so I'm trying the easy stuff first. Here's where we are so far:

-I recapped the set years ago.
-I tried subbing both the 6AQ5 & 6CG7 in the vertical circuit, as well as wiggling them around & watching for any changes.
-There is a 50mfd cap from the vert output xsfmr to ground; I clipped in another (the grille underneath is missing & I have limited access), no change.
-I tried the old trick of running a .047 cap from the grid of the 6AQ5 to filament to introduce a pulse of sorts & that gave me about 3/4" of deflection.
-I jumpered resistors across R122 & R126 with no changes.
-I've tried tweaking vert hold, height & vertical centering, no effect. EDIT: I just pulled the front control panel off so I could try the vertical lineage control. I found that if I turn it rapidly I get a some deflection, but only as I'm turning it. Is that a good clue?

I'm going to try to grab some voltages & do some further poking & prodding. I really enjoy tinkering on sets like this & some may think I even know what I'm doing-but I'm not the greatest diagnostician. As always, advice is welcome!
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Last edited by bgadow; 10-21-2017 at 10:12 PM. Reason: Additional information
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Old 10-21-2017, 10:58 PM
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Update: I tinkered some more & decided to concentrate on that vert lin circuit. I ran a jumper to R127 which is connected to the wiper of that pot (the far end of the pot goes to ground). I then connected it through a resistance box to ground. At first, nothing. I then noticed while switching it around to different settings that I would get the same limited deflection. I then tried the vert lin again-and up popped the raster! Now I have the resistance box unhooked & it still works. Some sort of intermittent somewhere, maybe in the pot? It remains to be seen if it stays stable.
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Old 10-22-2017, 12:08 PM
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Iím only across the peninsula from you, if you wanna play with my roundie test jig.
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Old 10-22-2017, 10:51 PM
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Quote:
Originally Posted by miniman82 View Post
Iím only across the peninsula from you, if you wanna play with my roundie test jig.
Someday I have to come up with an excuse to see your collection! I played with the set for about an hour this morning without trouble. I seem to recall this same issue with an early bw set, maybe my 721TS, where the vertical osc seemed to need a "kick-start".

The convergence so far hasn't been as far out as I thought; mostly it was the static convergence being off. I can't quite figure out what caused it to change like it did. Could it be tied to the DC circuit they used on the -5?
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Old 10-23-2017, 12:33 AM
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Quote:
Originally Posted by bgadow View Post
... The convergence so far hasn't been as far out as I thought; mostly it was the static convergence being off. I can't quite figure out what caused it to change like it did. Could it be tied to the DC circuit they used on the -5?
I think if you happen to get a tube and yoke that requires little DC convergence current (the pot wipers are sitting at the tap point) then you will have minimum sensitivity to line/B+ voltage. But if your set needs more DC current for static convergence, then it will be more sensitive to line fluctuations. Don't ask me to experiment to prove my assertion, as I don't want the pain of having to readjust it after screwing it up.

I wonder, has anyone tried subbing a permanent magnet cloverleaf in a -5?
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Old 10-23-2017, 11:50 AM
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Donít think so, but it would be nice is someone figured out how to add the later style diode pack at least so there wasnít so much interaction between adjustment pots.
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Old 10-23-2017, 08:55 PM
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Glad to know I'm not the only one who has fought with that. When they went to the newer design they made a real leap forward.
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Old 10-30-2017, 10:00 PM
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I wrapped up the convergence last night; while I'd like it to be better I need to be happy with what I have. Really, for 60+years old it's doing a fine job. It's out pretty far along the left edge but if I dial that in I lose the center convergence. I also found that I need to jiggle the hue control on occasion-cleaning the pot might remedy it but I'm not in the mood to pull that chassis right now.

And the vertical problem that caused me to post? I've run the set for several hours in recent days without the least bit of problem. I really need to force myself to watch it at least once a month, just to keep it in tune. One thing I've found is that the program doesn't have to be that great; I just get wrapped up in watching what this set is capable of!
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Old 10-31-2017, 12:04 AM
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Old 10-31-2017, 01:38 PM
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That image is fantastic. It's walk away time.

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Old 10-31-2017, 07:17 PM
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The color on that set don't come near today's cartoon looking color from flat screens, it looks great.
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Old 11-03-2017, 03:31 AM
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Very nice.
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