Rebuilding G07 with donor tube + yoke. Low B+ Issues

[Tithis]

I'm working on getting a G07 I've had up and running. It came with my midway cocktail and at the time I just swapped it out for a 19" K7000 I knew worked great. This was how it looked last time it ran, with a picture of off to give an idea of how narrow the screen was.



I ditched the tube years ago and saved the yoke, hoping to fix it some day with a new tube. I grabbed a 90s TV with the right socket type, but it had a low impedance yoke. I wanted to avoid the trouble of doing a yoke swap if i could, so I tried rewiring the vertical coils from being in parallel to being in series like the original yoke, and this roughly quadrupling the resistance to 52.8ohms. This is a bit less than the original yokes 55.6 but within ranges I've seen online. Horizontal is only .2 ohms off from the original.


Then I put in a new flyback, cap kit and B+ filter cap, adapted the various connectors and fired it up today.


I'm pretty pleased with the vertical, linearity isn't perfect but not bad at all. Horizontal is pretty wonky and squished near the top, but based on the old burn in the squished image was a problem for LONG time. Saw some similar looking issues on G07s with low B+, tested mine and its showing about 99v. Adjustment pot was at the max clockwise and adjusting it back and forth did nothing to change the B+

I've gone and tested the following resistors in the power section out of circuit. Nothing seems drastically off.

R903 5.2Ω
R904 10kΩ
R905 18.5kΩ
R906: 152.3kΩ
R907: 32.6kΩ
R908: 47.4kΩ
R910: 2.74kΩ
R912: 800kΩ
FR901 218Ω

And I tested the adjustment pot, which seemed to go pretty smoothly from almost nothing to ~1950Ω

Looks like I've be expanding my search to the transistors and diodes in the power section, but if anyone has any ideas of other things to test I'm all ears.

[Tithis]

Had some success without actually finding a smoking gun, but once everything was soldered back in place and I fired it up the adjustment pot actually started affecting the B+ and I got it stable at 116v, which was enough to eliminate the distortion. My guess is was me re-flowing the voltage regulators pins, or a cold joint in one of the other components.



The B+ pot is very erratic though, so I will be replacing it. Rather than get a NOS one I'm going to be installing the G07 remote board kit from Twisted Quarter since that also replaces the B+ pot. That will hopefully be enough to get the B+ stable at 120v and I can move on to things like getting the width right.

Plan ultimately is to build a 3rd cabinet to join my 25" upright and 19" 4-way cocktail, a 19" Atari style cabaret for 8 way shooters.