1962 Magnavox Stereo Theater with a busted Theater...

[electra225]

I have to pull the chassis to dig much deeper. I need to figure out how to run the chassis on the bench with no CRT. I'm not getting much help from the "TV guys". I appreciate your input, Chris. Every component I have checked is okay so far,

[electra225]

I didn't have to pull the chassis. I found the plug on the CRT shorted cathode to grid. I pulled the plug apart and overhauled it so the terminals were better insulated. I need to make some adjustments to make the picture as good as I can. Centering, maybe some horizontal width. The horizontal lock can be touchy if you are using the antenna, so I'll adjust the horizontal frequency so it won't be so touchy. I have no idea how long this set will work before something else happens. I may touch up the changer while I have the back off. I've been putting it off because I didn't want to remove the back just to tinker with the changer.

[electra225]

In the event someone is reading this and it will help them, I'll fill in some of the blanks.

First off, very few Magnavox TV sets of any description have survived. The only ones that still remain in any quantity are the ones in the various Stereo Theater models. It is very rare to see a stand-alone Magnavox TV and even rarer for it to be a color set. I don't know if they didn't sell many TV's or if they were such poor quality they all got junked. The solid state models are somewhat more plentiful. The tube TV's in Stereo Theaters survived because they were in the stereo cabinet, and people continued enjoying the stereo long after the TV set quit working. Now these are being taken apart, the stereo equipment sold, the TV parts all get junked. Parts for Magnavox TV sets are rare as hen's teeth, the picture tubes are unobtanium for the most part, particularly the 27ZP4 tubes used in the 400 series top-of-the-line models. As far as I have been able to determine, the 27ZP4 and the 23MP4 picture tubes were only used in Magnavox TV sets. The 27" only in Stereo Theaters. Magnavox never made a 27" stand-alone set that I know of. I don't know if the 27" TV tube survived into the Astro-Sonic Stereo Theaters or not. Service literature is scarce and not all that accurate. Magnavox factory literature is scarce as well. I was fortunate to get literature years ago, some from a man who may no longer be with us and some from a forum member who was good enough to share. Otherwise, you have to improvise. Accurate schematics for my Stereo Theater does not exist. Few people know much about them. Information on the Internet for Magnavox TV sets is scarce.

When this one got a fully bright picture tube, I shut it off almost immediately. I only ran it about five minutes before I got it fixed, just ran it long enough to take electrical measurments. It was so bright, I was worried about stripping the cathode or otherwise damaging the pix tube. I did the bulk of my troubleshooting by taking resistance measurements and by checking each individual component. I didn't find ANYTHING wrong with the set. I have a cathode to grid short. What was the one place common to both cathode and grid? The pix tube. Unplugged, it checked okay. Plugged in, it had a cathode to heater short, dead short, 0 ohms. That is when I unplugged the pix tube and checked the plug itself. I found it shorted.

This particular set is not terribly complicated, thankfully. It hasn't proven to be reliable, but, in its defense, part of the issue may be due to my lack of knowledge and lack of experience repairing TV chassis. The first thing that happened recently was a shorted NOS RCA 6EB8 video amp tube. So shorted that when I put it into the tester set to the correct settings, it pegged the needle and the short light came on even before I pushed the "Test" button. Every element in that tube is shorted to the next one per my ohmmeter. Never had that happen before in the 40 years I have been working on this stuff. Next was a shorted CRT plug. How often does that happen, and happen suddenly? Time will tell is this set will be reliable or if I should just leave the back off so I don't wear out the screw holes in the cabinet. It has a gorgeous picture, when it works, and the sound is amazing. Magnavox ran the audio of the TV thru the stereo speakers instead of having its own 4X6 speaker like many manufacturers do.

Two things I learned working on a Magnavox TV set. Don't change all the tubes even if they are Radio Shack. That causes issues you may not have if you leave the old tubes in until they prove themselves in need of replacement. The horizontal frequency in this chassis is now off, giving very delicate horizontal lock, largely because I replace the original horizontal oscillator with a new tube. No big deal to adjust it, but it caused me more work than necessary. Second, don't try to make the messy wiring too neat. The TV might not work at all if you do that. Having a wire tie on the wires to the pix tube may be a part of why the plug shorted. Some of the wiring can be sorted, but be careful around the picture tube. Clean the tuner thoroughly and carefully. My ST has a Standard tuner, not the best one they made, either. Cigarette scum can cause grief years after you think you have it cleaned up. Double, triple check you work cleaning the tuner. You will save yourself untold grief, particularly if you are working with a Stereo Theater. Removing the tuner after you get the other restoration done is a horror show.

I am thrilled to have this Stereo Theater. I wanted one for a long time. This has been quite the journey, getting the TV working as well as it does. Next up is working with the changer and I might even try to get the remote control working. Everybody who collects console stereos should own a Stereo Theater, Home Theater or whatever a three-way combination instrument may be called. Nothing quite like them. If you had one of these when they were new, you were serious about your electronic entertainment.....

[William]

Thanks for keeping us posted, Greg. I wish my RCA Home Theater still had the TV in it. As a console stereo it is great, and when the TV was still in the cabinet it played through the stereo's amplifier and all 8 speakers. I can remember sitting in my grandparents living room listening to LW on the RCA Home Theater.

Bill

[electra225]

The RCA color TV chassis for your Home Theater is fairly common. They made lots of them and a lot of them still exist. The TV guys hold them in high regard as one of the better color TV chassis ever built. A Stereo Theater/Home Theater device is amazing in concept and execution. There has never been anything like them, before or since.

[William]

The color chassis is probably out there and I know there are a lot of the RCA Mark II TV's, more common, out there but my Home Theater has the Mark I chassis, it is more deluxe with power tuning and a few extra doodads. And, I am not sure if a Home Theaters TV has something different because it uses the stereos sound system. Dave, MM would probably know, he has one just like mine.

Bill

[TC Chris]

I'm generally a restoration guy--one who favors making old things work again. There's the horror of seeing vintage innards tossed to "make a bar" or whatever. But when the TV chassis is unreliable and compromised, maybe there's an argument for installing a modern receiver in the space and using the good audio of the console with it.

Chris Campbell

[electra225]

I think Motorola Dave told me one time he had a picture tube for my ST if I needed it. I hope I can get this one sorted so I can enjoy it some. If you tried to put something else in my ST cabinet, you'd ruin it. Right now, at this very moment, I am somewhat optimistic I can get this thing sorted so it will work. You never know when or if something will fail. Not much use getting excited, just be ready to handle whatever it is then move on...

I have a 98 year old radio that is still running its original filter caps. I need to find someone to recone the speaker, but it still works just fine. The TV in the ST is ONLY 64 years old, practically a new one.....

The next TV I redo I'll do things different. First, I will inspect the plug on the CRT first thing. Gotta take it off to test the tube anyways before you get time and effort in the chassis only to find you have a bum jug. Look at it REAL close. With both eyes.....