#1
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1963 RCA CTC-15 roundie
Acquired a CTC-15 from a VK member here. It's in great shape and produces a nice color image.
Two questions: 1. After about 3 hours of operation, the color fades out to near nothing with a green tint. This does not happen gradually, it will be fine and then just loose the color all at once. Cannot bring back the color by switching the channel selector, fine tuning etc. After maybe 5 or 6 hours, if I turn on the set, it will be fine with great color image again. What should I check first? 2. The set is 100% original, so only plan to show it to guests that visit and watch vintage TV shows on DVD. What is best, leave the set plugged in or unplugged? Is there a trickle current in the set when plugged in?
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Personal website dedicated to Vintage Television https://visions4netjournal.com |
#2
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Well--the first thing I would check is to see if the 3.58MHZ osc. is running--when you lose color. It most DEFINITELY sounds like either the crystal itself, or maybe a cap or such in it's ckt. I also would get a voltage reading on the plate and grids of the burst tube--and any in the ckt. with the crystal--when you DO have color--and THEN again--after it goes away. You might find a big discrepancy, between the 2 conditions.
As for "trickle current" in this set--the answer is NO..this set did NOT have any sort of instant on ckty--so there should NOT be any current drawn by it--when switched off. If there IS--then SOMETHING is not right--such as a leaky line-isolation cap-- and MUST be looked into. |
#3
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burst amp tube, color osc tube, band pass amp, check color killer setting.
If you turn the color down (while its working) is the green tint there (grey scale setting). |
#4
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No. Good grey scale. When it looses color, barely there mostly green, like a tint with severe mute of color. Sometimes after the condition sets in, intermetent color pulses.
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Personal website dedicated to Vintage Television https://visions4netjournal.com Last edited by etype2; 10-18-2014 at 06:04 PM. Reason: Typo |
#5
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When the 3.58 craps out on most tube RCA's it gives you a
pink & green pix. Not sure if this applies to the -15. Its distinctive when you see it. Dont remember the layout but its best to get at least one known good 6GH8 & sub it once at a time. Do not move them around it will cause confusion. 'GH8's will work fine in one place but not in another...... Lots of folk would bring in all the tubes for testing & when they put them back in had different symptoms. Not this but also watch for a short jumper wire at the demod tubes that carried the filament voltage. Very common. Its brown & dries up badly. 73 Zeno |
Audiokarma |
#6
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99.99% confident it's the 3.58 section. Saw a lot of them in the shop.
Phil |
#7
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You all mentioned the 3.58 section. Thanks for the lead, will update later.
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Personal website dedicated to Vintage Television https://visions4netjournal.com |
#8
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A few screen shots of the CTC-15 when working properly.
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Personal website dedicated to Vintage Television https://visions4netjournal.com |
#9
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Could you post some shots of when it's not working properly. That might help verify it's condition.
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"Face piles of trials with smiles, for it riles them to believe that you perceive the web they weave, and keep on thinking free" |
#10
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I could do that. When the color go's about 3 hours after it's turned on, it looks like black and white with just a hint of color. When the scenes shift, I can see the color trying to come back a bit but very faded out. Best description I can come up with.
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Personal website dedicated to Vintage Television https://visions4netjournal.com |
Audiokarma |
#11
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Sometimes the 3.58 osc. just needs a tweak one of my roundys would take ~1/2 hour to have it's color synch, work for a few hours then flake out again. Tweaking the osc. slug while messed up cured the issue.
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Tom C. Zenith: The quality stays in EVEN after the name falls off! What I want. --> http://www.videokarma.org/showpost.p...62&postcount=4 |
#12
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That set sure produces a great color picture, when it's in sync, Yowza!! :-)
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[B]"Bee care-eh-full to don't broke thee pic-sher tee-yube!" :-) |
#13
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Let the set run for 3 hours...
until the color problem rears it's ugly head. Then perform a complete AFPC circuit alignment.
This will either fix the set, or reveal which circuit is malfunctioning. |
#14
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always go for the easy fix 1st, wiggle tubes, esp the color osc.
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#15
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Thanks guys.
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Personal website dedicated to Vintage Television https://visions4netjournal.com |
Audiokarma |
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