Neotec NT-500DX pincushion not adjusting fully

racer

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Donor 2012
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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!
 
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I've now replaced Q717, Q714 and Q715 to rule them all out and no change. My only remaining guess is the deflection IC since the vpp off pin 24 is lower than the schematic by nearly half, which coincidentally also is about how far the pincushion adjustment goes. I have a new one on the way, we'll see if that fixes it.

Also I double checked the B+ again and it's spot on 140vdc
 
Replaced deflection IC with a brand new TDA9116, no change. Guess it goes on the naughty shelf until I get some more time.
 
The final part of the EW circuit, the diode modulator D709, i.e. upper and lower damper diodes built-in a single package that looks like a HOT. Easy to check. Also, C713 in parallel with the lower diode.

Is the horizontal size adjustment working? Attach voltmeter to the middle leg of D709 and see if the voltage changes smoothly from 0V (maximum size) to about 40V (minimum size).
 
The final part of the EW circuit, the diode modulator D709, i.e. upper and lower damper diodes built-in a single package that looks like a HOT. Easy to check. Also, C713 in parallel with the lower diode.

Is the horizontal size adjustment working? Attach voltmeter to the middle leg of D709 and see if the voltage changes smoothly from 0V (maximum size) to about 40V (minimum size).

Thanks for the reply. D709 seems to test good with the correct voltage drop out of circuit. C713 seems to test good but I don't have a replacement on hand to try instead--I'll order one. Horizontal size works fine and adjusts the full range.
 
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