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Zenith SJ2775BG picture distorted

 
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oldsguy
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PostPosted: Wed May 17, 2006 12:02 pm    Post subject: Zenith SJ2775BG picture distorted Reply with quote

This is a SJ2775BG, 9-1054 module TV. The picture does not consistently behave; the most common symptom is the picture being shifted down or folded over with a 2-3" horizontal black line in the middle of the picture. Also, there is some intermittent horizontal deflection too - I believe it's called "pie crusting" - (ie if you look on the left edge of the screen it looks like a pie crust and the whole picture shifts like this intermittently)
I resoldered the vertical output IC and while that did help clean the picture up quite a bit and it even holds a correct picture occasionally, I am still having the problems.
Can anyone help?
I've heard about replacing the fusible resistor on the B+ to the VOIC but I haven't a clue how to identify this resistor. Are there any caps I should replace, and if so, which ones specifically?

Thanks,
Chris
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PostPosted: Thu May 18, 2006 6:24 pm    Post subject: Reply with quote

Replace as many electrolytics as you can around the chips, especially the ones near big resistors or heatsinks. (don't forget the small electro's) Use high temperature low ESR replacements. It will pay to test/replace all filter capacitors. If a fuse was blown I would think that the problem would not be intermittent.
If there is a larger electrolytic next to or inside a U shaped Verticle IC heatsink, try and mount the replacement under the board away from the heat if there is room.

Let us know your progress. Smile
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PostPosted: Fri Jun 09, 2006 8:22 am    Post subject: Reply with quote

I went through and tested every capacitor, and pulled about 10 off the board before I realized that my DVM was set for the lowest resistance which evidently was too small a charge to actually charge the larger capacitors (oops!). But anyway, i did find 5 bad caps and ordered replacements. Everything is soldered back into the board now, but alas, I found that my notes as to what goes where were quite inadequate (was I drunk?). I was able to relocate all abut two of them successfully, but now I'm afraid to fire up the set until I know that I put all the caps back right - I don't want to risk cooking this TV because I didn't write enough down.

Anyway, does anyone out there happen to have a service manual or schematic for a Zenith SJ2775BG (9-1054 module, 9-1092 sweep) that they could look up the values of a couple capacitors for me?

The numbers on the board are:
C3472
C3422

Notice now, how close the numbers are! I discovered to my dismay later that part of the "2" in "3422" had rubbed off, leaving something that looks very much like a "7"!

Any help would be appreciated,
Chris
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PostPosted: Fri Jun 09, 2006 8:30 am    Post subject: Reply with quote

An additional thought:
The two caps I am dealing with are small, of identical size, and of the values:
50v47uf
16v100uf

C3472 is right next to the horizontal width adjustment screw outside the vertical IC heatzink. C3422 is on the other edge of the board near a big coil and a bunch of big caps of 50, 160 and 200v. My gut feeling is that the 50v one goes here due to the voltage of the surrounding components.
any thoughts?
Chris
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oldsguy
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PostPosted: Sat Jun 10, 2006 4:21 am    Post subject: Reply with quote

Does someone just have a schematic they could email me?
I just fired it up and blew a different capacitor (25v2000, one of the new ones)
My email is fastcarson -at- prodigy.net

Chris
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fongs
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PostPosted: Wed Jun 14, 2006 1:51 pm    Post subject: Reply with quote

Hi there,

One suggestion I have for u is to download the vert. IC datasheet. The datasheet usually comes with sample application circuits that show u the caps values.

Hope it helps... cheers. Smile
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