Focus Adjust on neck board - Toshiba PD2367

[Buddyc]

Has anybody used this pot for anything?
Mine does not seem to do anything....
Focus on the flyback works as intended, but can’t se much difference using this though.

Appreciate any tips & tricks you might have!

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[PrincessPrinPrin]

The last generations of Toshiba tubes had dynamic focus. Both grids forming the focusing lens had adjustable voltages. The voltage for the G3 comes from the flyback (as usual) while the voltage for the G4 comes from the anode voltage through a divider that consists of a fixed resistor placed inside the tube and a variable resistor connected to the former through a neck pin that is normally not used in this neck type. Nanao cheaped out with their MS2931 and used a fixed resistor instead of a variable one.

[Buddyc]

Fantastic info. Thanks a lot!

So on a Toshiba PD2367 chassis this pot does nothing?
Just did a full recap with lovely Rubycon caps and damn.... Picture is super sweet even before calibration

[PrincessPrinPrin]

If it's a Toshiba tube of the type A68KZN or A68LBT, yes.

[Ioncannon]

I just wanna comment: That is the worst pot placement I have ever seen.

[Sunder]

Being a former Canadian, we all know what the ideal pot placement is.