Pentranic 1125 no image.

Lolerooz

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Hello all!

I recently came across this 25" Pentranic 1125 that was completely dead. After replacing two resistors in the power circuit daughter board I was able to get it to come back up. The problem I have now, is that I can only get a raster line to show up, no actual image whatsoever. No matter what adjustments I make on the neck board/flyback/adjustment board, none of them seem to make much of a difference aside from changing the raster line appearance.

Any of you have any experience with this? None of the caps on the board seem leaky, although I am planning on replacing them soon. Maybe just shotgun recapping solves my issue?

Here's an image of the display.
1000005777.jpg
 
Does it have an LM1203 IC on the neck board? I have had to replace that once or twice on similar chassis when I got no video.
 
Likely no 200V supply to the RGB transistors on the neckboard. Check voltage at one of the common legs of the three big resistors R961/962/963. If no voltage there, check R409 near the flyback. These should be the schematics:


If all good on the 200V (it doesn't have to be exactly that but something in the 180-200V range), check voltage on R724 also on the neckboard. One side 18V, other side 12V.
 
Last edited:
Hello all!

I recently came across this 25" Pentranic 1125 that was completely dead. After replacing two resistors in the power circuit daughter board I was able to get it to come back up. The problem I have now, is that I can only get a raster line to show up, no actual image whatsoever. No matter what adjustments I make on the neck board/flyback/adjustment board, none of them seem to make much of a difference aside from changing the raster line appearance.

Any of you have any experience with this? None of the caps on the board seem leaky, although I am planning on replacing them soon. Maybe just shotgun recapping solves my issue?

Here's an image of the display.
View attachment 749570
Looks more like one of your I.c.'s are bad.
They're good monitors but flybacks are no longer available anywhere… just a heads up
 
Likely no 200V supply to the RGB transistors on the neckboard. Check voltage at one of the common legs of the three big resistors R961/962/963. If no voltage there, check R409 near the flyback. These should be the schematics:


If all good on the 200V (it doesn't have to be exactly that but something in the 180-200V range), check voltage on R724 also on the neckboard. One side 18V, other side 12V.
Perfect, will do
 
If all good on the 200V (it doesn't have to be exactly that but something in the 180-200V range)
I dont believe I have the switchable version of that monitor, but I ended up testing the three large resistors in the neckboard and they all tested at around 200v, would it be a safe bet to assume its LM1203 that's bad in that case?
IMG_20240617_130656.jpg
 
Check if it's getting 12V first. And if you replace it put it on a socket.
 
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