Heathkit GR-53A color TV

[Ralph S]

I got a Heathkit GR-53A 21" roundie as part of deal to buy an early RCA color set and had stashed it for sometime. I've recently pulled it out of storage to see if I can get it running. Have any of you worked on this model set and if so what sort of problems did you run into? I'm very close to having the whole thing recapped and have found a number of unsoldiered connections which I've fixed and a few questionable diversions from the published schematic which I've corrected. Any thoughts or caveats to relate?

PS: The picture tube is in great shape electronically (very good emission,) but has the usual cataracts which will have to be removed.

[old_tv_nut]

Wow - this sounds great. Have not worked on one, but eager to hear your experience. If you have the manuals and are restoring according to them, I'd think that's all that is needed.

[dieseljeep]

Originally Posted by old_tv_nut

Wow - this sounds great. Have not worked on one, but eager to hear your experience. If you have the manuals and are restoring according to them, I'd think that's all that is needed.

The roundie Heath, was a another clone of the RCA CTC15 design. I remember the color circuit as being identical.
IIRC, the IF and sync circuits were slightly different, as well as the audio.
It shouldn't be too much different, than troubleshooting an RCA.

[Username1]

I have put together a couple of heathkit items years ago, and in some cases when they made changes in the assembly, they published an attachment, but you still got the original instructions. Have you checked to be sure those diversions are needed, or mistakes...?

[Electronic M]

Got any pics?

Those roundy Heathkits are so rare I've only heard of them been offered...I did not know any still exist.

[Ralph S]

Well, here's the latest news on the Heathkit: I finished the full recap, replaced a bunch of bum tubes and then did a voltage run up and very soon had sound and picture. 1st major fault was that the local color osc won't lock and keeps coming up with slightly high multiples of the correct frequency! I've got to track this down. 2nd fault occurred after the set had run for about 1/2 hour, with a large drop in the Y signal. I haven't got this nailed yet either. Overall pix frequency response is good.

Don't get the idea that I'm whipped on this one, just have to give it some reasonable diagnostic time. I've decided I'm not going to touch the cataract until everything else is under control.

The recommended production changes (page of 138 in the manual) have been done; no further modifications. Don't worry!

[wkand]

Originally Posted by Electronic M

Got any pics?

Those roundy Heathkits are so rare I've only heard of them been offered...I did not know any still exist.

Agree... Can't wait to see pictures!!! Very cool project you have there, Ralph S !!

[Steve D.]

Originally Posted by Electronic M

Got any pics?

Those roundy Heathkits are so rare I've only heard of them been offered...I did not know any still exist.

Here's a link to some tech facts on the HEATHKIT roundie: http://www.radiomuseum.org/r/heath_n..._gr_53a.html#a

-Steve D.

[Einar72]

There used to be someone on here who used a catalog picture of the Heath 21" roundie - with Madman Muntz added to the CRT image photo - for his avatar.

[Ralph S]

Here's the latest news: Found the problem with Y signal failure: the original kitbuilder failed to solder various connection on the "color board." The intermittency was caused by a wire just stuck in a hole. Every time the board was touched the signal would be fail. I'm willing to bet that I haven't found all of the "non-solders" yet, but I'll be more eagle-eyed as this goes on. I realize now how easy I've had it with previous restorations on sets which were factory produced. At least you knew that at one time they did work in the intended manner. You don't know that with kits.

Now to solve the chroma lock problem. My Tek scope failed yesterday, so time to switch to another one!

[Tim]

Glad you found the problem. Sets leave the factory with mistakes also. When I restored my 630TS I found that the connection to the input of the first IF was never soldered nor was one of the wires on the flyback. It may have exhibited intermittent problems for years for the original owners.

[wkand]

I had an AJ series tuner years ago that I bought from the original owner. It "warbled" when in stereo mode. He said it had always done that, but neither of us had the diligence to fix it. Could have been a wrong or defective component, or as simple as your case of a missing solder joint.

[Ralph S]

Here's the report d'jour: I've got the color problem solved by resetting 3 transformers/coils: 3.58 Mhz transformer; reactance coil; burst phase transformer. Now color bars and broadcast scenes are as they should be. Now the only thing that's bugging me is horizontal hum that looks like a hula dancer in slow motion. Remember, all caps (electrolytics and tubular have been changed.) Any ideas?

[Ralph S]

I should add an addendum to my report above. I have not yet changed any parts on the convergence circuit board. This means that the three sections of diodes are still the original seleniums. Also, there are five tubulars which have yet to be changed. I was hesitant to do this before the basics were out of the way. What do you think? Could this board be the culprit causing the hum in the horizontal scan?

[wkand]

Hi Ralph:

Your hula dancer description leads me to believe the sets power supply filter caps are going bad not the convergence board.

The diodes and tubular caps you mention, are they on the convergence board?

What are the capacitance values of the tubulars?


If they are large finned diodes then yes they should be changed. But you'll need to watch the voltages after replacement as the drop across a silicon diode is different than selenium.