View Full Version : Oops, I did it again!


veg-o-matic
07-13-2004, 02:08 PM
Well, being too stupid to have learned anything from my recent DuMont debacle, I find myself now in posession of yet ANOTHER inoperative set.:withstpd:

The new one, a Heathkit GR100 just arrived today. Via UPS. The only damage I could see in the time it took to get from the loading dock to my car is that one side of the cabinet got bashed loose. It's a crappy particle board affair, so I guess I'll have to gouge out the old corner splines and put new ones in. Mmmmmmm. Wood glue...

As for the set itself, well, of course I haven't had a chance to plug it in yet. The seller said "it works" (guess we've all heard that before) but the horizontal hold needs to be fixed. Have no idea what THAT means, of course. Guess it'll be an adventure!

The reason I bought this particular one is that being a kit, I figured it would be more open and easier to service than the typical assembly-line set. I spent (wasted) some time at work today looking through the manual that came with it. Looks like everything's labled nicely and the chassis is on a panel hinged like a door so you can open it up and get at the undersides of things. The book has a bunch of service tips and troubleshooting stuff in it.

Please keep your fingers crossed that I can get this sucker to work! I'll be looking for support soon, so stay tuned!

Oh, and if anyone has the VHF knob for it (part # 462-233, 462-234)--Ant'ny?--or knows where I can get one, I'd sure 'preciate it.

Sigh. Apparently, I'm irrepressible. Someone really needs to repress me!

veg-o-matic
07-15-2004, 02:52 PM
Okay, here's what I done did so far, which isn't much but it's a start.

After pulling the (self-contained) chassis out of the cabinet, I fired 'er up and all I got for my trouble was a bunch of diagonal lines on a green background. the green I'll worry about later, I'm more concerned with the lack of horizontal synchronicity, or whatever the hell it's called.

Okay. Installed a 6EW6 tube, which was missing, and switched out the horizontal oscillator with one pulled from my infamous Dumont. I believe it checked out good when I sent it off.

More diagonal lines, more green. Sometimes purple. And an alarming sizzling sound coming from the (I think) HV cage when I adjust the horizontal hold knob. If I turn the knob slowly, I get SOMETHING on screen; if I turn it quickly, the screen will go blank until I stop.

Okay. The Heathkit book says to replace the sync/AGC tube, which I ain't got one of so I'll have to order it. The book also said to replace one of the caps and I did. Sort of. I'm a little unclear about the value, though I'm pretty sure it's wrong. The set calls for a .003uf cap and what I stuck in is a .0039m job. I get my m's and u's and p's confused but I figurred what the hey, maybe it'll do something. P.S. When I was at Radio Shack, the closest they had was a .01uf cap. Would that have been acceptible?

Anyhoo, fired 'er up again and there didn't seem to be much difference. But wait! If I adjusts the horiz hold veeerrrrrrryyyyy slowly, I can get a picture on screen, though now the whole thing is scrolling sideways. And it doesn't take long before I get those diagonal lines again.

I'd post pics, but I hate my camera and the batteries seem to be dead anyway. I'll get some more.

In other progress, I reglued and braced the side of the cabinet that took a beating in shipping.

Okay, remind me: I'm doing this why? :D

Bob

captainmoody
07-15-2004, 06:03 PM
Did you try replacing the horizontal phase diode?

veg-o-matic
07-15-2004, 09:08 PM
Originally posted by captainmoody
Did you try replacing the horizontal phase diode?

Gosh no! Didn't even know I had one! I'll try to locate 'er on the schematic and replace that bad child.

Uhm, is a horizontal phase diode hard to find? All I have are the vertical ones :D

veg-o-matic
07-16-2004, 09:27 AM
Okay. I'm looking, and I'm seeing a horizontal oscillator coil and a dual selenium diode.
Would either of these be what I'm looking for?

captainmoody
07-16-2004, 11:27 AM
It's the dual diode.

veg-o-matic
07-16-2004, 03:02 PM
Thanks, Cap'n!

wa2ise
07-16-2004, 05:07 PM
We used to have a tube Heathkit TV years ago, but it's long gone. Except for a few pieces, like this knob below. Is this the knob you need? The chrome plating has worn off the finger grip but otherwise looks okay. VHF and a "UHF" position.

Yours for the postage.

bgadow
07-16-2004, 09:34 PM
IMO .0039 should be close enough for .003, but .01 is not.

I've noticed sometimes the horiz controls in the hv cage would have bad spots & cause evil noises as you turned them. Could be a bad control, I suppose, but that dual diode would be worth trying. I had one go bad on a set last year and I couldn't get the pic to stand still for more than a second.

veg-o-matic
07-26-2004, 08:17 AM
Greetings, Gents:

Well, I've done a little bit of work on my Heathkit, and made a little bit of progress. Not much, but a little.

As per the manual, I replaced the cap it said might be bad, replaced two tubes, checked the value of a resistor (it was good) and replaced the dual diode. Also tried adjusting the horizontal something coil--oscillator? efficiency? Think it was oscillator.

Anyway, with careful adjusting of the horizontal hold control, I can get a pic to stand still for a couple of seconds, but after that, it starts scrolling sideways again. Doesn't really turn into diagonal lines, the whole picture starts flying sideways. I can get it back again (temporarily), but it requires very careful adjusting of the HH control. Like a millimeter too much is enough to send it scrolling again.

Any ideas what I should check next?

The picture is still green, though I reset the grey scale (?) which brought in nice black & white for a while. Now it's back to green, but I'm not going to worry about that until after I can get the picture to stay where it oughta be!

Not gonna post any pictures until I've made enough progress to make it look presentable!

veg-o-matic
08-02-2004, 12:43 PM
You coulda knocked me over with a feather.

I was going over the sound/sync board checking the values of resistors when I noticed what might have been a loose connection. I wasn't sure, as I couldn't find it in the assembly manual. In short, it was a cap with one leg soldered to the PCB and the other one sticking in the air. Near it was a short length of wire, also soldered into the PCB.

What the heck?

Thinking I'd either accomplish something or fry myself, I fired up the set and got the typical horizontal problems. Touched the wire to the cap leg with a pair of insulated pliers. Horizontal locked. Disconnected the connection; no lock. Touched 'em together again; lock.

Woo hoo!

Went ahead and soldered the two together. Actually, it looked like they had been soldered together in the past anyway, so I don't think I did anything dangerous.

Of course, a new problem popped up. Now that I have a steady (if green) picture, I did the grey scale alignment or whatever, and couldn't get any blue. That's odd, 'cause I had plenty of blue a week or so ago when I last did the adjustment. Would a gun just up and die like that? I tried resetting the bias control as the instructions say, but that didn't do a dang thing.

The only other thing I messed with that I can remember is the color killer, but that wouldn't do it, would it? I don't have a tube tester, so I can't check the CRT.

If I can get past this hurdle, then the only things I still need to do are replace the cable between the antenna connectors and the tuner (got sliced somewhere along the line) and finish strengthening the "cabinet" (euphemism for crappyass particle board covered with Con-Tact paper!)

When (when not if !) I get this done, I'll post pics. Figure I'd do the whole beginning-to-end thing.

Onward!

bgadow
08-02-2004, 09:39 PM
Could be another bad connection. First thing I would do is follow the wires off the crt socket-the blue ones especially-and be sure they are hooked up. I say that because on 1 or 2 sets I have the blue wire had come loose from the chassis, meaning no blue screen. When setting up purity a switch box would be connected to these wires with jumpers to short them out and I think all that clipping & unclipping causes connections to pull loose. Just a possiblity.

(I think every time I have fooled with the purity on the CTC-5 one of those wires fell off)

veg-o-matic
08-03-2004, 09:28 AM
Well, here's a new development.

I checked all the wires that looked likely and they all seem to be connected to something.

I let the set play for a while and after about 20 minutes, the screen turned distinctly purple. Hmm. Purple means blue showed up.

So I did the grey scale thingie again and got a nice blue line. When I went back to the broadcast, I had regular color.

I'm hoping this is a tube, as I just spent 32 bucks on new tubes that the manual said might need replacing. Will try 'em out when I get home.

Looks like I'm having slightly better luck with this one than with that Dumont!

Chad Hauris
08-03-2004, 09:53 AM
Could be intermittants in the screen pots, there is 800-1000 volts there, also check for intermittants in the blue drive control if used.