It was a simulated stereo set. Has a speaker on both sides of the picture tube and a 10 watt amp mounted near the tuner.

Set came brand new out of box December 1980 from Harveys Warehouse in Gastonia NC. Picture of chassis.

Amp is in the left behind antenna terminal.

Well Noow. I have not seen that. Check voltages going to the amp chassis, look for wiring going back to the power supply. I don't have a schematic for the amp, well I might have it's just not with this chassis. Amp may have bad output transistors or IC, and may need recapping. I wonder if it has the standard sound module that could be used to drive one set of speakers. It wouldn't be stereo, but I would then have sound. Wish you were close to me, I would like to see this set.

I tried one speaker without amp. Got very faint sound at full volume.

Where does the amp connect to the sound module? Is that where you connected the speaker? What is connected to pin 5 of P! on the sound module?

A set of speaker wires come from the motherboard near the sound module to the amp. The pins are on the motherboard and i will have to check. I plugged these wires to the main speaker and got weak sound.

I think his sound problems are with this amplifier if he has a very weak sound with the volume turned wide open.

Yes, I think the external amp is the problem, or the B+ to the external amp.

I would get a ESR meter and ESR all the caps in the amplifier. That model had serious cap failure problem from the caps drying out. The description of the problem points that way!

Dont have an ESR meter so i am trying to find all the caps. Will let you know results.

You should check the power supplies first. That costs you nothing. Get the schematic.

I have the schematic. Thanks to Bill R. I checked power supply and have voltage.

:banana: :thmbsp: :boring:

I think your trouble is on the amplifier board. You might want to post a picture of the amplifier schematic and we can help you. There can easily be a blown pico fuse on that critter.

I don't think the amplifier schematic is in that folder. I was not that common. If it is not I would need to find another set that uses that amp.

Oh... Maybe Firebird can find some ID on the amplifier module for us?

I removed amplifier module to take pictures. When i reinstalled picture came back on folded in the middle with black bars on the sides. Then it changed to horizontal lines with black bars on the side. Then back to the folded picture.

Ext Sound Amp
 

Ext Sound Amp 704182-1

I will probably get in trouble for this but could a bad flyback cause such symptoms? No i did not replace parts with the power on. I did turn the adjustments on the sound amp and returned them as close as i could to original with no effect. The only thing that seems to effect anything is the adjustment on the horizontal oscillator board, with no change except it went from lines to picture. It was still folded in the middle. I have had electronics training but no experience repairing tvs so i have never seen this before.

Well....
Can you post a screen shot of what the picture looks like?
The flyback would have nothing to do with sound. I'm pretty sure your set has a flyback AND a high-voltage tripler. Now either of those could cause a folded picture if there was not enough high-voltage, but a screen shot of your set would help.
Your audio issue tho, would have nothing to do with that, so I'm wondering if you have 2 seperate problems going on?
Is there anyone in your area you could take it to for repair? You might be in over your head on this one. No offense, as I am NOT good on solid state stuff myself, especially a Magnavox.
So, I was trying to go thru your posts from the beginning. What was the original issue? I think you said no picture? IIRC you replaced the horiz output transistor?

I have been told several times that the flyback powers the sound. This has led me to believe it is either the flyback or tripler or both. I have tested the resistors and diodes. I found no defects. There are very few repair people left in this area and even fewer with knowledge of this type of television.

Well... whoever told you that gave you some major MISinformation, and if it was someone from this forum (which I doubt) I would like them to post and explain why they think that is. Audio has NOTHING do do with your high-voltage circuit. NOTHING.
To make it simple... a flyback and tripler act as a step-up device to deliver the 25KV needed to light up your screen. In your set (1981 Vintage) a flyback rarely fails, It's usually the tripler, and if that were bad, your symptoms would be either : NO picture, or poor focus, or.. if you have a high-voltage probe, you may find that the set is not putting out the 25KV needed.
In the years I worked in a repair shop, never once, was a no audio problem caused by anything in the high-voltage side.

Until we got pictures, nobody here even KNEW that your set had the power amplifier. The flyback supplies voltages allover the chassis, but NOT that power amplifier. Notice the power transformer... black thing... beside the power amplifier? That would be a power transformer for the amplifier.

Why did the picture fold when i turned the drivers on the amp? Why did it come back when i turned the driver on the horizontal oscillator? These are the things i find confusing.

Not sure yet what you turned on the amp. Were there any labels? I doubt turning anything on the amp caused the picture problem. A bad connection on the horizontal board would be more likely cause the problem, and touching the adjustment on the board made the picture come back. If anyone knows the sams number for a set with that amp I will look up the amp schematic. Shame you can't get the entire chassis here to West Tn. I would look at it for you. It would be to fragile to ship, but if you happen this way let me know. I have a test jig and really don't need the CRT or cabinet.

Module number is 704182-1. Chassis number is T815-009.

Young man, I suggest you take your TV to a qualified service technician. You apparently have no idea what you are doing and will only cause more damage to the TV or yourself. I am not trying to be offensive, but this thread has been going non stop with nothing but "shot in the dark" attempts at a repair, which is the most foolish way of troubleshooting. The members here have apparently made an "attempt" to help, but nobody can diagnose a TV on line for which they cannot see. There has been no attempt at gaining a schematic either which only contributes to more guessing games. A qualified technician with the appropriate diagnostic instruments needs the set in THEIR hands so that THEY can do the troubleshooting and get it fixed correctly and SAFELY.

I have a schematic, for some reason the audio amp is not on it and since there are no repair techs around anymore with experience in crt tv i am afraid that would be impossible.

Do not turn any adjustments unless you know what they are for. Guys the problem is that the amplifier schematic is not part of the sams set. I can not find any reference to an external power amplifier, yet there it is. I have been unable to find a schematic for that amplifier. i could possibly fix it if I had it here, but he is 7 or 8 hours away from me. if the set still has the on board sound module, it may be possible to connect one set of speakers to the speaker level output of that module. This is not where the external amp connects to the chassis, unless that set does not use the sound module called for on the Sams schematic. Firebird, you have more than one problem. As long as you have a picture concentrate on getting the sound working. Then, using the schematic you can troubleshoot the color problem. You still may have solder problems around the horiz. osc. board. The flyback and tripler are not your problem. They are fine. On newer sets most if not all of the B+ voltages came from the flyback windings. This is not the case on your set. Your flyback is fine, and would not cause any sound issues. Not having the schematic I would first check the output transistors or IC on the external amplifier. Then the driver transistors. Replace any that are bad and check any emitter resistors. Be sure the solder connections are good. I would then check every electrolytic capacitor with an ESR meter or just replace them all. Do not turn any adjustments. Right now we do not know what they are for, and if they were bias adjustments could cause you to blow new transistors. If there are no output transistors, there should be an output IC. Check it for shorts. Replace it if necessery. How may connections go to the external amplifier? If it only has power, signal and speaker out. I may be able to fix it without the rest of the chassis. Let me know. After you get sound fixed, you can move on to the Horiz Osc board, and its connections. This will get you a stable black and white picture. Then move on to the color issue. The color is processed through about 3 differnt modules, none of which will cause sound or unstable picture issues. So get the other problems solved first, the move to the color problem. Solder connections were a huge issue with these sets, I know you resoldered some of the connections, did you pull the chassis out and look at the bottom of the motherboard for bad solder connections?

Buy the way, is the fuse good on the power amplifier?

I put a new one on even though it wasn't blown. I resoldered the whole chassis. That was how i got it to come back, that and replacing the HOT transistor as well as replacing the safety capacitor with a regular capacitor. I resoldered the motherboard, connectors and modules.

Replaced the safety capacitor with a regular one? I'm not too keen on that. They are specific capacitors for the circuit.

May not have been much choice but to use a regular capacitor. The original may very well be NLA. Usually not a problem if proper size and voltage caps are used. Since it is a safety componant, and I always try to avoid litigation, I would never do that on a customer set, but on my set I might if it was all I could get.

I was told that if the original version failed it could destroy the picture tube.

I've seen it snap the neck off of a 23" CRT.

Other than the updated versions of the safety capacitors, I've never had to replace one with anything else.

T815-09

I plugged it in today, took off the back to observe. I use a digital box now as we no longer use cable and the satellite does not have an rf connector. When i changed channel to one with a cartoon the picture started trying to unfold and became full width on the left. Still a quarter inch black band on the right.

From looking around the net i have concluded that the problem is the Horizontal Oscillator module. Since no one seems to have one and i can not pin down the exact component, i will have to rebuild the module.

Good luck with that.

An odd film capacitor is near the horizontal hold driver. Numbers are M4/00 TRW 4700H. Does anyone know how to read this?