RCA Victor 21-T-8205 issues
 

Hello all! First post here. I've been a member of audiokarma for a long time, but I'm new to this place. I've not messed around with tvs a whole lot.

I found this tv at a garage sale about a week ago and have been fiddling with it off an on. (Its been finals week) So far the pictures show the best hold I have been able to get. The source is my Sega Genesis. I also left the tv on for a solid hour and did not touch the settings and the picture was not view able in the slightest. Some values seem to be drifting with heat. My goal is to get this television ready for semi daily use and from what I've gathered on the spacepages, its going to need a recap. However, I was just curious if this is what is required to get it at least somewhat operational. Any help would be greatly appreciated! This is my first electronic with tubes, so I'm definitely excited!

http://i1136.photobucket.com/albums/...age1%202_3.jpg
http://i1136.photobucket.com/albums/...er1/image2.png
http://i1136.photobucket.com/albums/...er1/image3.png

The fold-over on the bottom is indicative of bad vertical stage caps. The horizontal frequency being so far off is a symptom of bad caps in the osc, and or osc mis adjustment.

On many RCAs there are two H hold controls. One is a pot for the user to adjust (with limited range) the other is a slug tuned coil inside the set with greater range...I'd try adjusting the osc slug (if you don't know how to ID it GET a schematic before adjusting things). Make note of exactly how far you turn it so you can put it back. watch the screen as you adjust it so you see it's effect.

IIRC,on that model, the user HH control is the horiz frequency coil.
The first thing, I do is replace the .01 cap, across the phasing coil, located on the horiz osc board. The small board with only one tube, 6CG7.
It's a typical RCA Syncroguide circuit. Just about any RCA schematic of the same era will work.
The vertical circuit is different, as it generally needs a complete re-cap.
Did many of both. :sigh:

The service manual is located at the ETF website, under 21T8202, cabinet finish difference. :thmbsp:

What is the URL of this website? I'm having a hard time locating it based on just ETF.

So it would seem that this thing is going to need to be re-capped at least somewhere to get it functioning properly. I might as well go ahead and replace everything in one go while its apart. I've been watching some videos online of the processing being done on these older tvs and I've noticed that they use those oranges caps a lot and that what is in this tv has a different value system than modern. So, what capacitor type would be suitable and how do I properly convert to the newer values? Thank you all for the input, its greatly appreciated!

Visit Phil Nelson's website: http://antiqueradio.org/recap.htm

I believe in doing it in stages. First replace the horiz cap and get that circuit working properly. Unless you're experienced in restoration, you never know if another problem existed or it was caused by a mistake in component replacement.
Many on this forum don't believe in powering up an old set without using a Variac or at least, a series lamp limiter.
I'm in this line so long, I take a few more chances.
BTW, the website is the Early Television Foundation, Hilliard, Ohio. :thmbsp:

In addition to the recapping article mentioned by Gleb, here's an article with a few getting-started steps:

http://antiqueradio.org/FirstStepsInRestoration.htm

The following page lists a bunch of TV restoration articles. None of those TVs is identical to yours, but if you skim one or two, you'll see that the general process is much the same for all. One of my first restorations was a 21-inch RCA set; they will perform well after you're all done:

http://antiqueradio.org/televisions.htm

Regards,

Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html

I think the links already posted will give you a pretty good idea of how to convert the values, (round off). As to the type, I'm partial to the brown rectangular caps made by Panasonic and the like. The yellow ones have the right cylindrical shape but the brown ones color makes it less obvious that they are newer replacements, at least when replacing the old wax covered caps. This link is one popular source, but I also like Mouser and Digikey.
http://www.tuberadios.com/capacitors/

http://www.earlytelevision.org/pdf/r...202_manual.pdf

http://www.earlytelevision.org/tv_sc...grams_rca.html

I have neither a Variac or a series lamp limiter. Given that the tv works in its current state would I be fine with turning it on with just the horizontal re-cap or do I need to have one of the two?

Hey thank you guys for all the assistance and resources! I really appreciate it. I didn't have much time, but I messed around with the sine wave adjustment and it didn't produce any real change until it was at the end of its travel. Next week I will be able to sit down and figure out what capacitors I need and work on giving the horizontal section a re-cap and going from there. Since I've never done any real tv repairs I have a few concerns. Firstly, how does one properly discharge the tube? And is there anything I should know in the way of possible dangers?

You shouldnt need to lift the rubber like this video shows, but otherwise its right. https://www.youtube.com/watch?v=-jbnFuVWTdk Keep your hand on the handle of the screwdriver.

Keep one hand in your back pocket when working on it if it hasnt been discharged. That prevents voltage from going thru your heart if you get zapped. Stay away from the caged area where the flyback is and the wire that goes to that hole you are discharging.

I did a recap a year ago on a large rca of that year but the chassis is different. A lot of the caps I had to crush, loop the ends, and solder new cap on. Most of the important resistors were easy to test and replace. You may want to replace the electrolytic caps too.

Finally got time to work on it today. Got the chassis removed and identified the Horizontal Osc. board. Now to get to work on identifying the cap values and sourcing replacements. Anything seem suspicious just from looking at it? The top capacitor is covered in a goop, almost seems like it leaked.
http://i1136.photobucket.com/albums/...image1%203.jpg

ALL of those wax covered paper capacitors are likely suspect...just replace all 5 and be done with it!

jr

Alright, so after removing them to view the values we have (followed by available replacements):
1x .01 mfd @ 600V --> .01uf @ 630V
1x .22 mfd @ 400V --> .22uf @ 630V
1x .10 mfd @ 400V --> .1uf @ 630V
1x .47 mfd @ 200V --> .47uf @ 630V (Is the voltage jump too high on this one?)
1x .0012 mfd @ 600V --> .0010 or .0015uf @ 630V (I can go +/- 20%, but I am not
sure which would be best)

From my understanding, mfd is equal to uf. Also, that going higher in voltages is perfectly fine and choosing a new capacitance value within +/- 20% is fine.
The other caps are MICA caps and from what I read, those are usually good. Is there anything I'm missing and do the replacement values seem viable? Again, thanks for all the help!