UPDATE: Great Mystery Magnavox TV 27MS3404/17 Problem

Hi,

Thanks to everyone who offered their help.

I managed to get the TV to stay on, although I didn't find out what actually was causing the shut down. I have Photofact 4968 for this model TV, but there is no information about IC7200, TDA9577H. I couldn't find a data sheet for this IC on the web. I suspect it relates to the beam current sensing circuit or IC7200. Parts tested good and voltage measurements were right on, or not far from values in Photofact.

I noticed if I increased the brightness with the pattern generator, the TV starts to go off. I reduced (which were not set very high) the picture settings such as brightness and picture/contrast, as well as the color level. Then I increased the "screen" a small amount. Note: I had tried different "screen" settings before, but that didn't fix the problem.

Now the picture is a pretty good (it was good before), and the TV stays on. I ran it on and off for a number of hours.

Brad

Hi, > > I have a Magnavox TV model 27MS3404/17, chassis L01.1UAC-7638 >(mfg. 06/05) in my service shop that comes on, picture shows for a few >seconds, then the TV goes "off". Actually the horizontal sweep shuts >down. The SMPS is still "running" at "full power" (Reg B+ is 130V). >Note: The HV was around 27KV with picture showing. > > If I use a pattern generator (color bars, cross hatch, etc.), the TV stays >on!!!!! However, with a normal TV signal, it goes off in a few seconds >after the picture shows. With no signal (snow), the TV stays on much longer >but it still goes off. It only stays on with the pattern generator!!!! > > Note: I had tried different "Screen" (on FBT) settings. > > Any idea what is the cause of this weird problem? > > Thanks in advance, Brad > > Before you type your password, credit card number, etc., > be sure there is no active keystroke logger (spyware) in your PC.