I was given this chassis which originally had a series of power faults. I now have it running, but the pincushion adjustment will not adjust within the full range. I can get the center to bow inwards like an hourglass at the minimum value but not outwards at the maximum. To be clear: the adjustment is working--it is not completely dead.
I can see the bias waveform being output all the way through to L703. The only difference I can see is that the schematic waveform says pin 24 output should be 0.8vpp whereas I'm getting 0.5vpp. The 12v supply is at 11.44v which should be fine? Also, it should be noted there are no issues with width being too large/small and the issue persists on all resolutions.
So far I have replaced C727, C745, C725 with no change and checked all the passives in the EW bias circuit. I pulled Q714 and Q715 and they both test good out of circuit. I don't have replacements to try on hand. Q717 also tests good. Considering it's outputting a waveform, I wouldn't guess the deflection IC is bad?
I do have another fully working chassis I can test against but it's currently in a machine and I'd prefer not to pull it if I don't have to. If anyone has any ideas where to look next let me know!
I can see the bias waveform being output all the way through to L703. The only difference I can see is that the schematic waveform says pin 24 output should be 0.8vpp whereas I'm getting 0.5vpp. The 12v supply is at 11.44v which should be fine? Also, it should be noted there are no issues with width being too large/small and the issue persists on all resolutions.
So far I have replaced C727, C745, C725 with no change and checked all the passives in the EW bias circuit. I pulled Q714 and Q715 and they both test good out of circuit. I don't have replacements to try on hand. Q717 also tests good. Considering it's outputting a waveform, I wouldn't guess the deflection IC is bad?
I do have another fully working chassis I can test against but it's currently in a machine and I'd prefer not to pull it if I don't have to. If anyone has any ideas where to look next let me know!
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