Heathkit GR-53A color TV
 

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.

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.

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...?

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. :scratch2:

Got any pics?

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

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!

Heathkit GR-53A
 

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

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.

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.

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!

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.

Heathkit GR_53A
 

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.

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?

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?

Heathkit GR_53A
 

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.

All right, it's time for another report. The set's picture and sound reproduction are working fine with the major exceptions being: The horizontal weave previously described, a tube socket which needs replacement and some buzz in the sound on certain typical over-the-air scenes. The socket change and the sound alignment will come later, but right now I've reached the end of my rope on the hum in the deflection. It shows up in the secondary windings of the yoke and convergence transformer - being a beat between the 59.97 of the vertical deflection and 60 hz, so the movement is rather slow but considerably pronounced. On the primary side there is a .390 v p-p hum at the top of the 40 mfd cap and about .185 v p-p hum on the +390 vdc feed. The hum cannot be seen at the plate of the vert. output tube and on the feed side of the primary winding. BUT get to the secondary winding feeding the vertical yoke and it's very obvious.

I've tried slapping extra 100 mfd capacitance on both the C19 cap to the primary winding and the +390 vdc feed to the green/white lead of the secondary and R42. There is no difference by either of these additions.

What's going on here? Any positive ideas would be appreciated. Check the portion of the schematic below for the area I'm talking about.

If you have a tuning eye type capacitor checker I'd recommend checking all lytic capacitors between the secondary of the power Xfmr and the vertical stage(also double check that none of the lytics are wired in backwards.). Check the B+ rectifiers for leakage if they are not tube also.
Heater-cathode shorts on tubes are also a potential source of AC leakage into the B+.

The PS doubler is working fine and all of the electrolytics along with the tubular caps are new. Before they were put in they were checked with an ESR meter and a capacitance bridge for correct and tight values. I tend to agree with you that the most suspicious site would be a heater to cathode short, but so far I haven't found it (or them). I've gone through the two major pc boards with a fine-tooth comb and haven't found anything out of the ordinary. Any other thoughts? Bear in mind that this set was assembled by a rank amateur a long time ago and I've already fixed an "arm's-full" of construction problems, but there may be more. Thanks for your comments.

A 'hula dancer' weave sounds more like ripple on the B+ feeding the horiz sweep and/or horiz osc. areas.

wow, hula brings back fond memories of my BW magging with the loose screw on the sweep board, which was a pressure connection of the ground on the pcb to the metal chassis.

I ended up finding it by feeding DC from a battery to the various tube filaments, one by one returning to the AC supply. Triple check all chassis grounds esp if there is a common cathode/filament return to ground on the sweep boards.

Confusing!
1) you have a HORIZONTAL weave
2) you are looking for it on the vertical yoke.

a) Is the weave a deflection from side to side (that is, the left and right sides of the picture go the same direction) or is it a size change (left and right sides of picture go opposite directions)?
b) Is there any vertical motion at all?

I agree with you regarding that the idea of finding the source of the hum in the vertical side sounds silly, but I've spent days checking the horizontal side and no hum appears there, only on the vertical side. There is a very obvious, slow moving hum in the vertical side. It's counter intuitive, but true! That's why I reached out to the group to try to get some help trying to nail this fault. I' stumped. The fault displays itself as a slow weave from side to side, traveling up the screen, then repeats exactly in step with what I see on the scope. On the 21" screen, the movement is almost an inch of screen width.

Ok, my guess then is that the signal on the vertical is not related to the problem, except that it happens to be coming from the 60 Hz line.

I'd poke around the sync separator / amplifier (whatever's in that area) and maybe the AGC at this point. Can you post the schematic for the sync section?

I still think you should check the grounds, if there is a common ground for the deflection board (assuming it has a PCB) then a defect in the ground could see a beat freq with the vert vs AC , then share that with the horz (same ground on pcb) and get some modulation on the horz tube cathode. Power up the filaments on the deflection with a 6v battery and see if it goes away. On my hula it would take something like 10-15 seconds to work its way thru (a vert line would show a slow moving horz shift like a hum bar, but much slower).

Here's the AGC, Sync Sep and Vertical section of the Heathkit. If you need the Horizontal section, let me know. I'm going to take a look at the Horizontal section again this afternoon. If I stumble into something, I'll let you know.

A picture of the symptoms could also help...

Well, thank you to all who replied and if I had a live TV feed to videokarma, you'd see me knocking my head with my fist for not checking this first: it was the PCB grounds as Dave and others suggested. I had put a tight ground bond on the IF board several days ago and only checked the Video/Color and sound/sweep boards with an ohm meter at that time. But the moment I bonded the grounds to chassis on those two boards the problem was solved. What a relief! Now on to getting rid of the nasty cataract and getting the color setup spruced up. MANY THANKS AGAIN!!!

(PS: I'll try to get some pictures out tomorrow!)

Good! Onward...

As promised, here are two off-screen shots showing the present stage of the Heathkit GR-53A set. The bars are from a Sencore VG91 and the live shot is off the air from KABC news at 11:00 AM. I didn't adjust anything between the two shots. The cataract is very evident, but the picture in the center tells the story. Also, horizontal hum/weave is gone!!!

looking good :thmbsp:

Looks nice. But I was hoping to get to see a picture of the whole TV. :)

Kevin it'll be a while before the set is put together and tweaked for best performance given that the CRT has to be decatted. In any case, you will be shocked to see what the cabinet is for this set. It'll make you wonder what the thinking was when the choice was made.....

Lookin' good. A bit of patient trouble shooting and some help from your VK friends paid off.:thmbsp:

-Steve D.

The following is really aimed at Dave WM because he's the guru of cataract removal and because I wanted to include some pictures I think you all might find interesting.

I've pulled the CRT out of the chassis assembly in preparation for removing the cataract, but I wanted to send you some photos to confirm the type of resin used. I suspect that this was a "Zenith" type of construction. The first shot is the only label on the tube. Nothing says RCA. The second shot is the join of the safety glass, resin and faceplate. It was a very easy matter to run a short blade around the circumference of the tube, in the resin. The third shot is a piece of the stuff showing its crumbly texture. The fourth shot shows a screwdriver inserted next to the faceplate and pulling some of the resin away; no serious resistance! What do you think? I suspect that this is a candidate for the "guitar string" method.

that is an rca cataract

If you can find an EIA number on a label, that would tell you the maker.

http://www.triodeel.com/eiacode.htm

RCA 274
Zenith 343

yep that is the RCA type, not gooey green (like jelly really).

if you can dig out big chucks and its relatively pliable, then you will need to wait for a very hot day, let it sit out in the sun and start in with the clothspin wedges. very gently is the key just let slight pressure do the work. it can take a while but you will see finger shadows develop reaching inward, just go back and gently tap in a little more and then walk away. If you can I would let it soak for a couple weeks just to make it a bit easier.

Strange that the tag on that tube seems to indicate that it 'employs integral implosion protection' which is what I believed to be the metal band which surrounds most of the later square CRTs. Never seen a tag where the 'integral implosion protection' sticker implicates a bonded faceplate.

That's an RCA tube, they used that label in the mounting band area.

News update: Last night I placed the tube on sponge rubber and toweling atop a lazy-Susan bearing which made it possible to rotate the tube as I injected distilled water containing a few drops of dish detergent to aid wetting. Using medical syringes, the injections were spaced about 1 inch apart and went in about an inch in the resin between the safety glass and the tube face. On average I was able to get in 1 to 2 CCs of liquid in each position. By the time I was finished getting around the circumference, I was able to easily remove almost an inch wide strip of resin from completely around the tube. I then soaked the tube overnight up to just above the gap between the safety glass and the tube face in the same solution. This morning I decided it probably wasn't necessary to waste a lot of water filling a tub, but rather simply keep the gap filled with liquid and refill it as needed. We'll see how this works. So far, so good.

The resin in this tube doesn't seem to be as rock hard as DaveWM described in some of the tubes he worked on, but I bet that exposure to air promoted hardening when the clear edge tape was removed and the time between removal and water application could be measured in hours or days. In this case, the water application was pretty soon after tape removal. This is pure conjecture on my part. Thoughts anyone?