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SubScorpion

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Jan 9, 2021
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Hoping someone here has seen this and can pinpoint the suspect part causing the issue. As you can see in the screen shots here, I can't get the width to expand full screen. On top of that, there's compression on both sides of the image (most noticeable on the grid image). Basically something is not allowing the image to expand to full capacity.
20210501_060215.jpg20210503_160301.jpg
Here's what I've determined it's NOT due to swapping the parts with another known working one:
flyback
HOT
width coil
linearity coil
C37
C36
C38 (lowering the value only exacerbates to compression on the sides)
C51
H Hold pot
D15 & D18 (both were tested and not shorted)

I've tried it on 2 different tubes, both with the same result. I'm at a loss as to what other parts could cause the restriction in the image. Any ideas out there?
 
it feels like a cap - i dont have a schematic handy but dont trust any polyester box type caps in the flyback circuit.
 
it feels like a cap - i dont have a schematic handy but dont trust any polyester box type caps in the flyback circuit.
Well if you have a chance to peruse one and pinpoint caps to check (other than the ones I mentioned I already swapped) let me know. I'm schematically challenged.
 
It should fix your compression though. That cap is for S-correction.
 
It should fix your compression though. That cap is for S-correction.
I don't have anything bigger than .39uf (what's currently installed), could I add a .10uf and run them in parallel?
 
I don't see any reason why you couldn't.
So i tried it and your theory was correct, it did aid the compression a little bit but as I stated earlier, the image is still being restricted as you can see here clearly with the brightness turned up:
20210509_095557.jpg
No matter what size width cap I install, I can't ever get the image to expand into the black area of the screen on either side. There also seems to be a slight linearity issue best seen here:
20210509_095643.jpg
Most noticeable on the left side. Messing with the H Hold pot helps, but can't adjust it all the way out. I'm thinking maybe it's tied to the width issue or not really noticeable if the image was full screen.
Any other idea of parts I can check? I'm running out of options....
 
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