Rca 21-t639

[fujifrontier]

Hey guys. I recently found this lovely RCA 21-T639 outside of a house, a few minutes before the garbage truck came and took it away forever.

The lady who threw it out (not literally thrown, by its condition) said that it came with her house and had been in a garage area for years, she plugged it in and got sound but no picture, and she didn't want it taking up space so she kicked it to the kerb.

I saw it was missing a ballast tube so I dropped one in (after waiting 2 days for it to arrive from ebay), and plugged the TV in (don't yell; i figured if it had already been powered on and got sound, i just might be lucky....). I got sound and a blurry horizontal line. It got very sharp and then I heard that "TV high pitched mosquito noise" go very high, the sound cut off and I saw the Horiz tube (the one with the little cap) arcing purple and dropping sparks down its interior so i immediately unplugged the TV.

*sigh* you can flame me now.

What do you think it would take to restore this old beast to working order? It would look so nice my living room. Is there anyone who does restorations for sets like this?

[David Roper]

A ballast?

[fujifrontier]

yeah. i bought a NOS ballast tube and put it in.

i can't find anything about the TV on the net....

[blue_lateral]

A ballast?

Ok, were just a little surprised to hear that it has one. I don't think that was common in an RCA of this vintage. There are some members here who work on sets for others. It would probably help if you posted your location.

Almost certainly it can be fixed. There are probably some parts in it that could be showstoppers, but odds are it can be fixed.

It's old enough to have paper capacitors, so those should be replaced. Testing the crt would be a good thing to do.

John

[Steve K]

Hi:

Your set is from 1956. The RCA 17 inch sets of that era had a ballast tube, I believe, but the 21 inch sets had a standard transformer and 5U4 rectifier tube power supply. What is the chassis number? Should be something like KCS-97.

Steve

[fujifrontier]

I'm from San Antonio, Texas.

I stay at my dorm; the TV is across town. I'll check on it soon and grab the chassis number. Yeah, it has a ballast. The diagram says so. 6AX4 GT, is the tube, i think.

[Steve K]

Actually a 6AX4 is a damper tube. I am surprised that the diagram calls it a ballast as a ballast tube is usually a resistance device that is found in a power supply to keep current constant.

Steve

[bgadow]

If it was mine I would replace all the paper & electrolytic caps & put in a new horizontal output tube. Chances are very good that it will then work. You could skip some caps and just try the ones in the horizontal/HV circuit but my experience is that those caps you leave will come back to haunt you. The vertical section in particular will not work right with marginal or bad capacitors. As Blue Lateral said, having the crt tested would be a good idea. If it was very weak or bad you would then have to face locating a replacement. Not the end of the world but it might make this not worth the effort. Maybe you can borrow a tester from somebody? It wouldn't have to be a very fancy unit. I'll admit that if I was in your shoes I would get impatient and throw another output tube in there and see what happens, but that is not what you are supposed to do!

[fujifrontier]

the horizontal tube (it has a little "hat" connector with a wire leading into a HV cage) has a metal ring around it, on the chassis. Since it was connected to the HV cage and had that metal attachment to the chassis I didn't want to touch it, even a couple of days later since I dunno what's in the cage (a giant capacitor, with my luck). It's like a metal ring that's bent upward on the sides. I tried prying it up gently with a flat tip screwdriver, but no dice.

also, the picture tube isn't an RCA. it has the 60s Sylvania logo... obviously someone loved this TV enough to retube it. I don't think the tube is weak -or- bad, judging by how bright that horizontal line is. So.. who wants to fix my TV, LOL. I suppose that in order to do a complete and accurate repair I couldn't just ship out the chassis, because you'd have to align the tube and all that. *sigh*. How would you ship an old, heavy beast like mine, anyway?

[bgadow]

That bent metal arrangement is there to hold the tube in place, often used on rectifier and horizontal output tubes, especially on sets with a vertical chassis (the chassis is up and down, usually wrapped around the neck of the crt, instead of laying flat on the bottom of the cabinet) this was common around the time your RCA was made. You need to push down on both sides of that spring while pulling the tube out. I know, because those HV cages are tight it can be unnerving to have both hands down in there. You can discharge the HV by shorting the picture tube HV lead to chassis ground. One method is to get a large, straight slot screwdriver and connect its shaft with a jumper wire to the chassis, then stick the tip behind the connector of the crt so that it shorts. You will hear a snap if there is voltage stored there. Leave it there for a few seconds and then do it again. Then it will be safe enough to work in the cage no matter what you touch, provided the set is unplugged!

You wouldn't need to ship the whole set for repairs, you could just send the chassis to someone who could use a test CRT to power it up. Still a pain to ship but doable.

[fujifrontier]

you know, I would be more than glad to ship the chassis out to bring my new (old) friend back to the land of the living. I would love to watch some old movies on the thing. Something tells me if you fed it MTV it would blow a tube in spite.

I've been obsessively researching vintage television. I'm being driven by much the same desire; it's weird but I like to listen to MP3s on my (mid to late 50s) Zenith tube radio, just because I like the rich, liquid, mellow warmth of tube audio. I suppose it's a testament to their design and engineering that they still serve us 50 years later... I bet if I bought a TV at walmart today, with new caps and etc, the RCA would outlive it, even with 50 years under its belt.

[fujifrontier]

Chassis numbers (by the electircal socket):

KCS101
603L5
RBV274

they were stamped one line after the other.

the chassis does indeed look like a PITA to remove. I tried removing the gun connector but it feels reeeally loose so I'm not gonna F it up. How did ya'll get over your fear of ruining things and start fixing these beasties?

[Charlie]

I'd bet capacitors would be all you need. If you got light on the screen earlier (even though you lost it), it's likely that the CRT is in good enough shape to give you a picture.

In the first photo... Is that a clock under the control door???

For future reference, don't do what you did again. Purple arcing and dropping sparks inside the horz tube are not cool things to do.

[fujifrontier]

Yes, it has a clock under the control door. So. Who wants to fix my TV?

[jstout66]

Chad Harris is in Texas isn't he? He could do it. Not sure what area he is in, or how far of a drive it would be for you.