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this one is getting interesting. couple things, the HV reg is still not right as I have to have it set fully CCW to just get it to 25kv.
The horz scan is about 1in wider at the top than the bottom. I was reading my serv manual and found a comment about the pin cushion and the vert pulse off the vert out screen. This is what I was looking at above, and checking for a cap. They mention a cap in the screen circuit that should be checked but do not mention which cap. I figure it has to be one of the ones that is not found on a roundie which does not have pincushio correction. pretty sure I have check them all but will look again.
When I scoped the screen grid of the Hot I get a def vert freq pulse, not exactly sine wave but sorta, has a lot of hash on it which I assume is horz freq from the hot. I am going to compare this to a working zenith with pincushoion correction and see how it looks to be sure.
while checking around the HOT checked the drive voltage and pattern. I get about -55v with a vtvm, and the scope showed a correct pattern at 150vPP.
sams and zenith service manual have it at 250-270v pp. Not sure if that is related.
oh and I will prob check the pulse from the horz osc to the HV regulator tube while I am at it, to compare, just in case that pulse is tied into the lack of proper regulation range.
I have NOT checked the yoke, did not really want to pull that off but prob will soon. Was also wondering if a convergence assy problem could be at work, dont know if that could effect the overall scan and increase the width a the top, seems like a long shot.
My plan now is to check the drive and that screen modulation of the HOT of a working set to confirm those PP numbers and the look of the HOT screen.
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