1981 Magnavox with a problem. - Page 11 - Videokarma.org TV - Video

Firebird · #**151** 04-01-2013, 03:53 PM

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.

holmesuser01 · #**152** 04-01-2013, 06:12 PM

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

Bill R · #**153** 04-01-2013, 07:53 PM

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.

Firebird · #**154** 04-01-2013, 07:59 PM

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

holmesuser01 · #**155** 04-01-2013, 08:48 PM

Quote:

Originally Posted by Firebird

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.

Firebird · #**156** 04-01-2013, 10:11 PM

T815-09

Firebird · #**157** 04-05-2013, 06:24 PM

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.

Firebird · #**158** 04-06-2013, 06:32 PM

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.

holmesuser01 · #**159** 04-06-2013, 10:01 PM

Good luck with that.

Firebird · #**160** 04-06-2013, 10:02 PM

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

Firebird · #**161** 04-07-2013, 11:57 AM

I need more than luck. Some advice would be nice.

Bill R · #**162** 04-07-2013, 08:42 PM

Check the power supply voltages going to the module first. Low B+ may also be a problem. I would check the electolytics with an esr meter, but I dont recall problems with the other caps.

Firebird · #**163** 04-08-2013, 10:26 PM

Power supply is fine, electrolytics are all new. I am having trouble finding the film capacitors and transistors on the board.

Firebird · #**164** 04-10-2013, 04:44 PM

Horizontal oscillator module number is 703881-3 if anyone has one.

rpm1200 · #**165** 04-11-2013, 12:03 PM

You can get an ESR meter for $50 from everybody's favorite made-in-China electronics supplier, matelectronics.com. http://matelectronics.com/test-equip...-mul-3333.html

Or if you have a scope and signal generator, you can use them as an ESR meter. Instructions here: http://fullnet.com/~tomg/esrscope.htm

As far as the black bands go, my guess would be that you bumped something around the horizontal module when you were troubleshooting the amplifier, but if you reseated the module and that did not fix anything, that's not the case. Maybe there's a width or horizontal hold control somewhere that is dirty and got disturbed?

Anyway, keep at it and troubleshoot one thing at a time. I am almost completely certain you are dealing with multiple failures that each need to be corrected, not a single failure that is causing all the faults you are observing.