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!

Sounds fine to me. :thmbsp:

jr

That'll work. I tend to do higher in value on paper caps rather than lower, not for any particular reason though. When the paper caps were new, they would have had tolerances no better than 20 percent, and in some cases closer to 50 percent. Either the 0.001 or the 0.0015 would work just fine.

I usually pick the closest value available so I can say it is in closer tolerance than it could have been.

A good habit to be in is to read the color coded values off the physically larger micas...Some are paper in mica's clothing. Usually there is a dot the color of which denotes dielectric type....If a mica has it's value textually printed on it then it is usually a paper cap.

Got the horizontal oscillator board recapped! WE GOT HOLD. So far this is the best adjustment vertically I can get. Is there some combination of adjustments I'm missing or would a recap of the Vertical Oscillator board solve this issue? I have no problems getting a vertical hold.
http://i1136.photobucket.com/albums/...er1/image2.jpghttp://i1136.photobucket.com/albums/...image1%204.jpg

I'd start by replacing all paper caps in the vertical circuits.

After doing that, I'd go to the service manual and look up the adjusters for height and vertical linearity. (Your pictures show a moderate problem with vertical linearity, where objects in the top of the screen are vertically stretched compared to the bottom area.) Note that these adjustments are somewhat interactive, meaning that adjusting linearity may affect the height a bit, and vice versa. You may need to go back and forth between the adjusters a few times to get the height and linearity just right.

Looking pretty good, otherwise.

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

I recapped all but one paper capacitor in the vertical oscillation board. I wasn't able to source a .0037uf 1600V replacement. So far it seems to be working well! Better than I would expect from an almost 60 year old tv. It took a little centering adjustment as well to get it about right. There are a few issues I am noticing though. I have a buzz in the speaker depending on a combination of the fine tuning on the channel select and mainly from the contrast control. Along with the contrast control, it is causing issues where depending on what is displayed (usually a lot of white and then black) cause some wave distortion within the image. I am not sure if this is just the nature of the beast with these older tvs or if maybe I need to look into the contrast control and where that leads. Thank you all for the help! Its greatly appreciated.

http://i1136.photobucket.com/albums/...1/image2_1.jpg
http://i1136.photobucket.com/albums/...age1%203_1.jpg

A buzz in the audio when graphics are on the screen using a converter box is very common. The signal from the converter boxes are not as good as NTSC broadcast. I have my converter box feeding a Betamax and that combination works much better.

One thing of note that I can't quite figure out. It hates signals from a VCR. I run my hdmi->av into the vcr, its fine. If I play a tape however, it curves off at the top no matter what I sat my horizontal hold to. Its driving me nuts.

It's not your TV set. VCR tape playing produces video with timing defects that older TV sets were not designed for and not expected to deal with. The only video they expected to see were from broadcast TV stations, that had timing equipment with tight specs, as the FCC mandated.

Specifically, the VCR produces video that has a major timing error in the horizontal sync timing that happens in the vertical interval. This is when the VCR switches from one video tape head to the other that is mounted in the spinning drum the tape slides over when in play. Your TV is trying to quickly readjust itself to this poor horizontal sync, the result is the curving at the top of the picture. Newer TV sets were designed to be faster at readjusting themselves, but then be less noise immune and be more jittery in noisy reception.

Well that is good to know! Thank you for the information. I was kinda of guessing that it was something to do with the signal from the tape itself. Looks like I'll just being using my amazon firestick and the converter to watch films. Would an RF modulator produce a good enough signal or should I just stick to using the VCR as the converter?

A time base corrector will fix that bend. Some DVRs and DVD-recorders have TBCs built in...Also some Sony S-VHS decks have decent TBCs built in. A friend had some such Sony decks, but they were constantly breaking, and he ended up trading me his 3-4 parts decks (and his busted main deck) for a good deck of another make.

So, even running the signals straight from the hdmi to av converter to a rf modulator I get about an hour or so of play time before the waves start to appear. Adjusting some settings can fix things for awhile, but its no guarantee. What section would be causing this timing issue? I'd rather not shell out 250 bucks for an external TBC. If anything, I will probably just attempt a full recap of the paper capacitors in this TV as it has now become my semi daily driver.

By waviness do you mean to say that with a digital source after a while the top of the screen starts to flag wave in a similar manner to what it does with a VCR?

If so there are a few things I would do: Change the lytics in the power supply (so we know the B+ rails will be stable) if you have not already done so. Make sure all caps in the AGC, sync separator, Horizontal AFC, Horizontal oscillator, and H output have been changed, and make sure all resistors in those stages are within tolerance, also confirm the tubes in those stages are healthy.

After doing that it may be wise to adjust the AGC after it has warmed up long enough for the sync to have gotten wavy. If the AGC is too high or too low sync may be affected. The AGC pot will have a low no signal zone where the picture fades to white, a good zone where sync is strong, and an overload zone where the pic will go negative and loose sync, and the audio may turn to buzz. Generally you turn up till you hit the overload region then back down just past the point where overload symptoms stop (some service lit for some sets specifies 1/4 turn below overload).

That chassis, while being a good performer, has a more basic AGC and not adjustable. I feel, some of those simpler design sets were intended to be used for OTA analogue signals.

Yes, very similar. However the wave issue sometimes appears within the middle of the image depending on what is displayed. Also a little bit of wave on the bottom of the screen can occur. When I get some time I'll have to go through and recap those sections. I have currently already done the horizontal and vertical oscillation boards. Its probably just time to do a full recap in sections as all issues seem to be related to them. As for the tubes, I have no way to check those out sadly.

BTW if the wave appears as a horizontal bar that slowly rolls vertically, then it is likely the Power supply lytics.

Usually power supply electrolytics start off waving then as they warm up thermally they work. If the power supply electrolytics are failing after they have been on a while they start to run warm to the touch. Be careful, my RCA CTC-9 almost had it's power transformer burned up by a leaky electrolytic.
I would try subbing a horizontal oscillator tube as heater to cathode leakage can also produce the symptoms you are describing.
What signal sources are you using?

I'm using a kindle fire into a hdmi to av converter that then runs into a rf demodulator. This combination is able to stave off the issue the longest. As for the waves.. imagine a side ways V that goes through and distorts the image. It does not roll. A combination of the tuner fine tuning, contrast control, and a little horizontal lock and can usually bring it back for another hour and then not much seems to help it.

Here are a few examples of some of the issues that will happen.

http://i1136.photobucket.com/albums/...image1%205.jpg

http://i1136.photobucket.com/albums/...image2%201.jpg
Notice that grey ish line in the middle. Under normal conditions that line is straight and centered.

I would recap it and measure resistors whilst performing the recap. You've already found crook caps in the vertical and hor circuits so it's highly likely that there are others just as bad elsewhere in the set. Once that's done you can address any remaining faults.

That is correct. Some of those mica caps also look suspect. Looks like one paper cap had exploded from being shorted.
I agree with them that say replace all paper caps, and, electrolytics so you will have a trust-worthy set.
I also see why the vertical has fold over, more bad caps. The audio caps are always bad. And, I've actually found damaged controls from shorted caps.
Bill Cahill