Last night, while watching a movie on our 3.5 yr old 51MP392H/17 Magnavox, we noticed that the picture in the lower left corner and upper right corner was getting yellow. This was true in High Def as well as "normal" t.v. mode. Tried the Convergence, manual convergence & even the old "restore factory settings". The red convergence is perfectly alligned, but the blue (it won't let me adjust the green?) while very sharp & centered in the center of the screen, but at the upper right and lower left, the blue and green +'s were way out of allignment, and even tilted. We attempted to adjust manually, but while I could get them to move left to right, I couldn't get them to move up or down. The problem seems to be getting worse each time the t.v. is turned on (and of course, being Friday the 13th....). We can't afford the $100+ for someone to come look at it, and my husband is very knowledgable about some electronics (and I can rebuild computers) - is there a fix / test we can do to a) figure out what's wrong and b) hopefully fix it ourselves without having to sell one of our children into slavery?
High Voltage Capacitor? Leave the set unplugged for 1/2 hour most components will selfdischarge, as for your problem, being a Magnavox, you have one of two problems, the convergence I suspect is what is blown out, this unit probably uses STK392-110 Ic's, I would suggest replacing with STK394-160e chips as they are probably shorted, some of the big resistors (1 or 2) may be opened up also, usually they change color. The only other thing that would cause usually a yellow color in the corners is the CRT Fluid, it changes from clear to Orange in color and clamps off the blue color from the fringes, I suspect the chips need replacement, dont forget to put some heatsink dope behind them, they are usually on the left in the front of the set (from the back) Big long heatsink that is fairly tall (probably the biggest heatsink in the set.) Good luck, and the repair usually runs around $350.
The heatsink Dope I use is a Silicone Heatsink Compound, on sets with 3 plastic screens the plexiglass goes outside (not side dependent), the darker unit with vertical grooves goes in the middle (grooves out) and the one with circular grooves - fresnel - goes inside.
On sets with two, just leave off the plexiglass part and the vertical grooves are the surface you view. Some newer LCD projection sets invert the vertical lines to the inside.
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Oh yeah...one thing neither of us is clear on, how do you discharge the high voltage capicitor so that you can work on the t.v. safely (and preferably discharge it safely so that 911 calls are not necessary)? I'm not treating this lightly, but I tried for over 4 hours last night to get this thing to refocus, short of threatening it with either a swim in the pool or a 17 lb. sledge and have had little or no sleep (and two teenagers that really want to see the new HBO HD channel(s) we just got).
Any help would be greatly appreciated.
Ok....we first checked the CRT fluid (clear) as it's easier to pull off the front (but I think we may have put the screen back on backwards.). So, here's another question....there are two layers on the screen, one shiny, and thick(almost opaque) and the other dark almost paper thin, and just a bit smaller. Which side faces out toward the viewer (I wasn't there when my husband took the front off)? Also, is heat sink dope same as zinc oxide?
I'm getting a rainbow effect with the color at the bottom of the screen. I've tried to manually adjust the color, but that doesn't work.
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