Who made magnavox tube tv's around 1967

[sparks_elec]

Who built the chassis, the one I have is a magnavox T939 chassis set. The mylar caps aged and ALL of them needed to be replaced. The convergence and purity is a little off, but I can't do it, it drives me crazy. After following the proper steps I could not get the entire screen, if the middle was great the corners were off, I just don't have the touch for it. It has a decent picture now.








Before I worked on it

[holmesuser01]

Magnavox built it.

I've had no real problems setting these sets up.

[DaveWM]

are you using a dot and cross bar generator? if not then it can be very hard to do a good job.

[Username1]

That Tri-Pointed-Magnetic Thingie on the neck of the picture tube don't look lined up properly
either.... That is most likely the biggest problem....

[sparks_elec]

I straightened out that convergence assembly, but I think someone got to it before I did. holmesuser01 and DaveWM, I have a dot and bar generator but could use some tips for this particular model. I can't believe magnavox made the chassis itself, I heard from a tech that these chassis were imported from japan, or rca made them. Here's some more pics. Is the flyback supposed to leak, it hasn't gotten any worse after I've been lightly using it. I never seen a 60's tube tv before, so I don't even know if this is as good as it's supposed to work. With the 60 or so parts I had to replace, makes me wonder if there's more bad parts (open resistors mainly as it had 15 open ones, those molded ones) Is this a top of the line set or budget? Was a real adventure getting to work at all, more like a voyage, or a 46 year old headache. It was fun actually, many people would not understand that idea.


Purple trail to the right of text, changes with the color adj, not with the brightness adj.

Flesh tones change with each scene change (blue sky will make red faces, red background will make green faces).

Black level shifts drastically with changes in scenes.

Convergence!!!!!

------------------------------------------

Color pattern





Crosshatch pattern






Corners






Is this bad? Looks like it might have happened years ago.

[Username1]

Well first things first, I think you need to address that ripple in the picture. It's in the
very first picture you posted, and it is also in the ones later, so I guess it is not the
signal source??? right ??? Different signal source for each of those pictures....
Is there hum in the sound as well...? Possibly AGC set too high, possible bad filter caps...?
AGC can also bring you those odd changes from scene to scene....
If there is a Sharpness control, you can turn it down and see what that does... I think
that set should not have one though...
I don't know who may have made it, Country of origin should be on it somewhere.....
I don't have much experience with Magnavox color sets. But your symptoms should be
independant of brand in this case anyway.... Good Luck ! Keep us posted....

[zeno]

The set is built by Maggy, they built most of there own
stuff. They did use jap sets for a few models over the years.
The squirrel is right, check the AGC & filter caps for the bend.
Edge convergence will never be perfect but the center will.
When you do it you have to go back & forth to the center &
do the process several times often. The controls also interact
& you often have to compromise a little.

73 Zeno

[jstout66]

Yes.. Pure Magnavox, not Japanese. And yes... bad filter can cap or AGC could be set too high. Also, don't forget to adjust the blue lateral magnet. The flyback looks fine, and I'm pretty sure it's a Thordarson replacement. ( I can tell from the black rubber coating) Thordarson made the BEST replacement flybacks.

[jstout66]

Also, the signal looks strong, but I see your antenna leads are on UHF in picture 2. Should be VHF.

[dieseljeep]

Originally Posted by jstout66

Also, the signal looks strong, but I see your antenna leads are on UHF in picture 2. Should be VHF.

You'll have to follow the leads coming from the tuner. The UHF and VHF leads might be swapped.
That was Magnavox's low-end model, that year. They used a 22KM6 horizontal output tube, that was short lived.
The set's more like a 1971-72 model.

[DaveWM]

agree with others, get the line straight 1st, AGC/filter caps etc...

shifting hues with scene changes... hmmm sounds like a defect in the burst signal to 3.58 mhz osc. the burst signal is used to lock the phase of the color osc (in some sets like GE's and other lower end sets the burst IS the signal that is used to demod the color). try tweeking the horz hold a bit when you see this happens. the burst is keyed by a horz pulse to only sample the video signal at the time the burst is transmitted. the pulse comes from the flyback.

This is not a fix just something to look for. I would recommend looking at tubes in the burst amp and any kind of phase detector in the chroma circuit. Also you should sub in a new 3.58 osc tube. You can also check the 3.58 osc is reactance coil is set, this is covered in the sams, you ground out the burst amp correcting voltage at the grid of the AFC tube and set the reactance coil so the resulting color bars do not move. this gets the 3.58 osc close to the correct setting. This is generally is done when you cant get a color lock, but it would not hurt to check it out, do not go crazy here if any adj is needed it will not be much. The fact that the color is working at all means it is at least within pull in range of the phase detector circuit.

the horz lines on the right are controlled by coils, they have peaks and operate over a fairly narrow range. IIRC they should be set 1st before the Left horz lines (done with pots). the main thing is to see if all the pots and coils do something. I had a issue with a CTC-7 that was from an open coil on the convergence board. Not saying this is your problem, but sometimes things don't work and all the tweeking in the world will not fix it.

http://www.youtube.com/watch?v=2wYn3xLrZj0

[dieseljeep]

Originally Posted by dieseljeep

You'll have to follow the leads coming from the tuner. The UHF and VHF leads might be swapped.
That was Magnavox's low-end model, that year. They used a 22KM6 horizontal output tube, that was short lived.
The set's more like a 1971-72 model.

I was wrong again! After looking at the first picture, it shows very clearly, that the antenna leads are proper.
I haven't seen sets, that had that many bad components.

[DaveWM]

regarding the flyback. a little bit of wax drippings is no big deal. However its always a good idea to dip the cathode current of the horz out. The sams covers this procedure.

[dieseljeep]

Originally Posted by DaveWM

regarding the flyback. a little bit of wax drippings is no big deal. However its always a good idea to dip the cathode current of the horz out. The sams covers this procedure.

As often as the 22KM6 has to be replaced, it sounds like a good idea.

[old_tv_nut]

Flesh tone changes with scene - don't try to fix until you have that horizontal bending fixed - could just be bad burst gate timing due to bad horizontal timing.

I'm also amazed at so many bad non-lytic components. Replacing the lytics may fix a lot of this.