1981 Magnavox with a problem. - Page 9 - Videokarma.org TV - Video

Firebird · #**121** 03-16-2013, 11:45 PM

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.

Firebird · #**122** 03-17-2013, 12:00 AM

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

Firebird · #**123** 03-17-2013, 12:23 AM

Amp is in the left behind antenna terminal.

Bill R · #**124** 03-17-2013, 03:40 PM

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.

Firebird · #**125** 03-17-2013, 04:15 PM

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

Bill R · #**126** 03-17-2013, 08:10 PM

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?

Firebird · #**127** 03-17-2013, 08:28 PM

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.

holmesuser01 · #**128** 03-17-2013, 09:19 PM

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

Bill R · #**129** 03-17-2013, 09:41 PM

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

Zenith26kc20 · #**130** 03-18-2013, 02:57 PM

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!

Firebird · #**131** 03-22-2013, 01:00 PM

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

holmesuser01 · #**132** 03-22-2013, 01:27 PM

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

Firebird · #**133** 03-26-2013, 12:31 PM

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

holmesuser01 · #**134** 03-26-2013, 02:08 PM

Quote:

Originally Posted by Firebird

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

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.

Bill R · #**135** 03-26-2013, 08:28 PM

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.