Tuner diagnosis on Magnavox TV

Oh, I just remembered there was either an rf or osc xistor that was a hi failure part too.
 I used ECG 160's to replace it with 100% success.

I worked for 2 Magnavox (sic) ASC centers.
 Many of their sets were total nightmares.
 Mostly I worked on the solid state sets, but:
 There should be specific chassis numbers on the radio, turntable, amplifier, and TV set.
 I might be able to find a schematic OEM or Sams from that info.
 The set "model" number pretty much means nothing without the special cross ref. Model to Chassis Magnavox produced. They "mixed and matched " a lot. Especially since the main difference between the low end and high end sets were 2 things.
 The high end sets had a better cabinet, and more parts on the chassis, with a few more features accessible due to the higher parts count.

If you can get the IF cable unplugged from the tuner, you can "buzz" test it with an audio gen or a finger.
 That should produce some sort of noise in the amp and something on the screen.

 The tuners were not that hard to pull. Often it took a 3' 1/4" nut driver, or 5/16" to get it out.
 Other models needed a "special" driver to remove the inverted control nut or the tint control mounting nut to get the tuner out. 
 It will be very difficult to troubleshoot the tuner without access to it.

Did this set have a remote? Was it an ultrasonic type or RF/IR type? Wired remote?
Some sets had a "mute" feature on the remote. IIRC, it operated a mechanical stepper relay to increase or decrease the audio. We had some problems with that area giving no audio.

 Do you get any audio noise or picture flashing when you rotate the tuner?

Is the raster "slick" or noisy?

Look for sockets on the TV chassis that have fallen apart, if this set uses a PC board chassis. The opaque or clear plastic ones would cook & fall apart killing everything in the IF. Usually they were at the bottom of a shield can for a tube. I would spend many hours replacing them on some of the models. Some were real PITA to replace too.

The TV audio runs thru the stereo amp. Is the amp set to "TV"?

 There is, IIRC (Trying to think bk to the 60's)  many inputs on the amp chassis. It was really easy to plug a cable into the wrong input/output.

 Is the amp solid state? If so they had a lot of faults that killed the audio. Mainly the black paper covered 'lytic coupling caps on the amp board.

 Is there any audio out of the amp at all on radio? AM or FM?

 Are you running the VCR video and audio into the tuner input, or into separate VCR and audio inputs?
 If so, is the tuner set to channel 3?

Is the VCR set to channel 3, not channel 4?

Oh, and some sets required the tuner to be set to a certain UHF channel for the VCR inputs too. It was a really ugly ball of worms for some sets. other sets had a VHF tuner position just for VCR, but I can't remember if "Maggotbox" did that or not. After a few thousand sets and a few decades, it all gets a bit muddled


To help, we need more data.

I thought I should mention that if you are successful in getting a signal (60 Hz or more) out of the the video amplifier stage to the picture tube, the Horizontal and Vertical hold will not stay in sync (very long) because a test signal from an audio oscillator or some other similar source not designed for TV service will not have any vertical and horizontal sync signals present.
Rod

I used to be a TV repairman and have worked on tube type sets but mostly did the solid state ones and they could be tough enough to solve at times. Mostly, if you hadn't seen the problem before you were in trouble trying to figure it out. Some problems can be signal traced and that is where a scope will come in handy.

Getting a raster is a good start for your set. You could try injecting a signal (audio range) at the video amplifier control grid and see what comes up on the picture tube. If you get something (some bars) then you could try adjusting the vertical and horizontal hold into synch.

Then you could work back and inject a signal (4.5 MHz) at one of the sound IF stages. I can't think off hand of a good substitute for an FM generator for this test. The simple generators used 60 Hz for the modulation frequency but the modulation level could be varied.

Likewise, do the same with the composite video IF amplifier (44-45 MHz approx.). Here the signal is AM so standard signal generators will work. Good luck.

73, Rod  WB6FBF

First off, do you have a TV digital converter to translate the digital signals into Analog? Because if you don't You won't Get a picture or sound (maybe just hissing).
My Expertise is null when it comes to TV.

Make Sure you didn't change the new components without them being exactly the same lead length and position as it may affect the RF circuitry.

Usually if it has an external amplifier the audio has RCA plugs and jacks. You can test the audio for buzzing sound by touching your finger to the pin end of the jack with your fingertip. You should get some 60 cycle sound. If so the audio is good. If not you may have to see about any blown fuses. You really Need to have at least a multimeter, to test voltages along with a High voltage probe if you are testing high voltages.
They Are Lethal!!!!!!
If you get no sound then your external amp may be faulty. If the volume controls Right and left can be reached use an insulated screwdriver and touch the center lugs and listen for a buzz. If no sound then you have some testing to trace the audio line. As Far as the rest I don't know. As you really need to get a book on troubleshooting TVs.

Try this book on bookstore searches, (I don't have one but this one by Markus is a well known Author of many electronics repair books.)
Elements of Television Servicing


by Marcus & Gendler; Prentice-Hall, Inc., 70 Fifth Avenue, New York, NY; 587 pages, many black and white photos and illustrations
A classic service guide for tube televisions. My copy is dated 1955; I don't know if it went through later editions. Written when TV was still fairly new, the book has several introductory chapters on TV theory, with other chapters devoted to the budding TV repairman, which explain how to equip a workshop, how to install antennas, etc. These are followed by many chapters on the theory, diagnosis, and repair of the various sections of a tube TV. An advantage of a vintage repair book like this is that it covers early features (such as electrostatic deflection picture tube circuits) which will never be mentioned in newer books. I own several other 1950s TV repair books, but this is my favorite.
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Go here fast if you want books on TV.
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This Forum is one that I was and Administrator for Some Time and Then left due to personal circumstances.

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I am in the process of restoring a Magnavox Stereo Theater.  It has a 27" black and white TV set in it.  I have gone thru the amp, radio tuner, Multiplex adapter and the TV chassis.  I refinished the cabinet.   We are dealing with a C36-20-11 model TV chassis.  This is my first TV restoration, and, in fact, the first TV I have done any work on outside of dusting and replacing tubes.  I am a total noob and am probably in over my head.  I have replaced every capacitor in the chassis, checked all the resistors, repopulated the chassis with all new RCA tubes.  The CRT tests about average, I guess.  Not great, not horrible.  I have raster.  I have cleaned all the "operator" controls.  I have not cleaned the "setup" controls on the chassis.  I have no audio and no picture.  I can't even introduce noise, like wiggling tubes and that, and get any response in audio.  The audio on this TV runs thru the stereo amp instead of the TV having its own speaker.  There is no audio output transformer on the TV chassis.  I connected a VCR to this TV and just got what I always had.  Raster.  I have no idea whether the horizontal or vertical are stable.  I have re-checked and subbed tubes in the video and audio IF, video amp, audio detector circuits with no change.  I'm beginning to suspect the tuner may be kaput.  I can't wiggle the tubes or anything in the tuner, since it is beyond buried in electronics and wiring.  I have no signal generators or test equipment for TV.  I don't even know what questions to ask, really.  Now what?  Magnavox made the best stereo equipment back in the day and housed it in gorgeous hardwood cabinets.  Their TV sets leave a lot to be desired.