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Old 12-08-2014, 03:58 PM
jbunnelle jbunnelle is offline
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Twitchy RCA CTC17 1966 Screen

This is my first time posting, so hi everyone! I recently acquired an awesome RCA CTC17 1966 television from a guy locally (Damen, he's the one who told me about this place). He has been awesome about helping out when I have questions, but I realize that if I want to keep this television for the long haul, I need to figure out what I am doing, or at least find the place to pick the brains of true experts. I know old portable manual typewriters pretty well, but this expertise is not transferring I'm afraid. Overall, the set is running solid. It has the same picture tube installed from 1969 (still had service paperwork!), which was apparently a replacement for the one that it came with. Damen replaced the melted flyback when he got it with a used one that still works. After talking about pros and cons, he recommended cutting a hole in the flyback's casing to allow dissipation of heat to lengthen its life, and I installed a good fan on the opposite side, which is keeping things cool overall. The test that Damen ran on the tube showed that it still had life left in it, so perhaps the flyback died back in the day and they decided to get a new set and store this one.

The only issue I am having now is that the screen is very twitchy, or sort of snap compressing from the bottom upwards. Damen and I are going to check some things this weekend, but I thought I'd post here in advance. Here is a pic.
https://drive.google.com/file/d/0B_w...ew?usp=sharing I tried all of the tuning settings on the front and carefully adjusted the hold on the back, to no avail.

The second issue is the shadowy vertical line on the left, visible in pic. The image tends to stretch there a little more than the other edges. Any idea what's causing that? Thanks, y'all, appreciate any help or insights you can give!
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Old 12-08-2014, 05:30 PM
DaveWM DaveWM is offline
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there are adjustment for vert height and linearty on the back as well as a vert position adj.

There are a lot of things that can go wrong in old tube sets here is a short list:

1) Dirty or worn control pots and switches
2) dirty or loose tube sockets
3) Wires that are stiff and break when moved
4)tubes that are weak/shorted or gassy
5)Capacitors (mainly eletrolytic types in this era) that are going bad
6)resistors that have drifted high or gone low. High is just aging and reg use, low is from a shorted tube or other defect that cause the resistor to get very hot and carbonize.
7)PC boards that are fragile (esp on high hour sets) with broken traces, hack repairs, and crystalized solder on traces and ground stakes
8)film caps, mostly in the sweep circuits that start to act up (can effect both vert and horz, but mostly in vert.
9)Broken coils from ill fated cleaning attempts of the PC board.

all of the above are typical. I suggest you get the volume one RCA color sevice manual a TAB published book by Carl Babcoke. This has a LOT of info on how the circuits work, and covers typical problems found in the field.

http://www.ebay.com/itm/like/1115410...ectorid=229466

this is a MUST HAVE book

Last edited by DaveWM; 12-08-2014 at 06:41 PM.
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Old 12-08-2014, 07:24 PM
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Tin whiskers in the pots are another thing to watch for.
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Old 12-09-2014, 01:44 AM
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Tubejunke Tubejunke is offline
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DaveWM made you a very nice list, but I want to add that (especially to the layman) the first two are the most likely for that specific condition, as well as being good, basic maintenance practice for anyone beginning in vintage electronics, or REAL electronics as I like to call it. LOL!

You need to gain a fundamental understanding of electricity to begin with and this is best found in old school text books. I have some nice ones in the classifieds section of this site if you want to take a look at the post. "REAL" electronics is almost a lost art and you can't even really learn it in modern day colleges or whatnot. The stuff uses much higher voltages and thus commands a whole lot more respect than what is learned farting around with transistors and other PN junction based components on a breadboard in a lab.

Learn your fundamentals and learn how to use a multimeter properly. You won't even have to think or use math as far as reading a modern digital meter display. If you like what you learn, move to a good quality analog meter like a Simpson 260 or better yet a VTVM! Welcome friend; be safe and good luck!
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Old 12-09-2014, 11:18 AM
jbunnelle jbunnelle is offline
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Hi guys, many thanks for the checklist and recommendations! Yes, a fundamental understanding is what I need, so that book would be ideal, I will grab a copy. I started looking for an old set somewhat naively, but Damen took me aside, opened up the back of a couple of his sets to warn me of what I was in for, asking if I intended to make this my main set or decorative. In other words, doing due diligence as a responsible, conscientious collector, which I respected and understood. Having no background in electronics, it is intimidating for sure; when you said "respect for voltage", yes, that's an excellent way of putting that. I'm 43 so I did grow up at the tail end of these days, have memories of smoking sets and grandfather's accompanying tirade, the man in the van coming, etc. But I think I am up to the challenge! Thanks for the warm welcome.

Last edited by jbunnelle; 12-09-2014 at 11:29 AM.
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Old 12-09-2014, 12:39 PM
DaveWM DaveWM is offline
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some selected reading on things like ohm law and the understanding of the meaning of voltage current and resistance will be a good start. I am sure there is tons of reading material on the subject. You will also need some tools of the trade if you intend to work on the sets.

soldering iron and gun
hand tools including wire stripper and diag cutters, some precision screwdrivers.

diagnostic equipment should be at a min:

DMM (digtital multimeter)
a nice analog VOM like a simpson 260
a VTVM (vaccum tube volt meter)
an HV prob.
and and bunch of jumper (aligator clips on lengths of wire).

most of the older stuff (like the 260 and vtvm) can be had for a fraction of the orig cost, but may need some work themselves.

I mostly use the DMM and the 260, the VTVM is close to a DMM but I prefer the analog readings I get, also since they were used back in the day when much of the service literature was published, I trust the readings from them over a DMM for such things as voltage readings given on schematics.

the HV prob is handy for setting up color TV High voltage (and a safe way to discharge a CRT which can hold a high voltage charge and give you a nasty shock).

The main thing is safety. These sets were designed to be serviced by folks that had training (school or OJT) and can be dangerous so you really need to pay attention and be safe. Again there is a lot of data on this you just need to search it out.
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  #7  
Old 12-10-2014, 01:29 PM
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Looks to have some foldover, so the 50uF cap (C507) in the cathode circuit of the Vertical Output Tube (Should be a 6GF7) is BAD. Always get rid of the original, and check any replacements.

Cheers,
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Old 12-14-2014, 12:13 PM
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Got him back up and running I pulled the vert lin. pot and took it apart and cleaned it tensioned the contacts and lubricated it and all is well again. We also replaced horizontal osc. 6fq7 tube that was a little weak. I added a picture of his set working a couple months ago when he got it from me.
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  #9  
Old 12-14-2014, 12:52 PM
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Woo-Hoo looks good !

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  #10  
Old 12-14-2014, 04:55 PM
DaveWM DaveWM is offline
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very sweet looking pic. love the CTC-17's
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Old 12-14-2014, 09:59 PM
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miniman82 miniman82 is offline
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Shame there aren't more out there, I suppose most get looked over because people assume they are just another square screen set. Oddly, RCA went back to round CRT's with the CTC-20. After that, it was square till the end!

Maybe one day, I'll add a '17 to my lot?
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Old 12-15-2014, 02:30 PM
jbunnelle jbunnelle is offline
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Thanks, Damen, working like a charm now! Very much appreciate your help on Saturday. Jim

P.S. Oops, I realized after the fact that this original post should have been made in the Rectangular forum. I'll post there in the future.
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  #13  
Old 12-15-2014, 08:02 PM
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Actually, the 17 could go in either spot IMO. It's historically significant enough to be in this forum, but it does have a square screen. I say keep it here! All you late model maggot boxes can stay where you belong though...

lol
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Old 12-16-2014, 10:24 AM
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Nice picture on the CTC 17, and Green Acres, one of my all time favorite shows!
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  #15  
Old 12-16-2014, 04:17 PM
consoleguy67 consoleguy67 is offline
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And what's wrong with Magnavox?
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