D9410 side squished

[lilshawn]

D9410, running 640x480 60hz.

working except for horizontal linearity at the edges.. it's squashing and expanding down quite a bit when the horizontal position is changed.

left side looks okay but also seems to move/expands when horizontal position /size is modified. thinking it might be something in the horizontal linearity circuit but not real sure... short clip of what it's doing...

https://photos.app.goo.gl/bBRDQE2LCdbi3U2CA

[lilshawn]

not sure what the deal is with it, it seems to operate normally at 800x600.

i thought maybe it was an S correction cap in the resolution switch circuit so i swapped out the 4 (c244 to c247) since i' dont know exactly which is enabled for that resolution...

but unfortunately it still seemed to do it. i did swap out all the switching fets and transistors coming from CS0/1/2/3 due to the monitors original failure. so i know it's not that. maybe it's a fried CS line coming from the CPU, but i don't know what the logic is for the different resolutions to dig into this more.

in any case, it's working good enough.

original failure was the typical yoke horizontal shorting out and dumping 195 volts into....everywhere. removed yoke and repaired/sealed the windings and re-sealed the neck insulation. replaced 48 components, diodes, resistors, caps, fets, transistors....  and managed to get it going again.

i feel this issue stems from the tube neck insulation drying out, cracking and flaking off. this insulation also seems to corrode and attack the lacquer insulation on the yoke windings (similar to how the yellow glue on the boards turns brown... then black and becomes corrosive and conductive.).... eventually a perfect storm of corrosion, bad insulation and static buildup.... eventually having a discharge into the h winding, the main switching FET shorts out, then all hell breaks loose. the chassis gets a shotgun blast of 195 volts to dozens components frying/shorting/and blowing open circuit stuff,  until nothing's left in the 195v path..and anything unfortunate enough to short circuit to a lower voltage rail. loads of fun.

basically everything in attached...