SE/30 screen adjustment

[PacificState]

My SE/30's display is shifted over too far to the right, and I want to center it. I've searched through the forums, and I understand that I need to adjust the rings on the back on the display. As much as I'm wary of doing this due to personal risk, I also can't identify exactly what to tweak - can someone point out which part of the neck I'd adjust? By the way - I do have one of @zigzagjoe's grayscale boards installed, but that's working great - this issue existed beforehand. Thanks!

 

[zigzagjoe]

These metal disks are your centering rings: if you adjust them it moves the image around. Recommend using a rubber glove while doing so. You may want to remove the bolle riser temporarily and put the grayscale card only, as to allow you to reach underneath the CRT easier.

If you haven't recapped the AB, definitely do that first, otherwise you'll need to adjust again most likely.

 

[PacificState]

Aha! It makes sense that it's *under* the tube, in terms of me not seeing it.

One question - the glove makes sense, but which parts of the tube (if any) carry high voltage when live - is it just the board at the back?

 

[croissantking]

Aha! It makes sense that it's *under* the tube, in terms of me not seeing it.

One question - the glove makes sense, but which parts of the tube (if any) carry high voltage when live - is it just the board at the back?

It’s the red flyback lead, I believe.

 

[zigzagjoe]

Anode lead [red] & flyback (many kilovolts), and neckboard (400v) are highly dangerous. The coils, I'm not actually sure about how much voltage they carry. Practically, the neckboard is the part you're most likely to accidentally contact where there may be exposed voltages - so don't do that

Incidentally, the insulating plastic from the rear of the apple neckboard may be transfered to the new neckboard (courtesy of @Bolle's design).

 

[PacificState]

Thanks. Of course, I get that adjusted fine and move onto tweaking the potentiometer to correct the screen height - at which point the plastic cap pops off, along with the inner 'screw'(?) and I'm left with a half-height screen

I'm comfortable removing the analog board, but I suspect I should do a full recap in the process - and also that the width pot has suffered the same fate (for what it's worth, I didn't insert the adjustment tool hard or extend beyond the range of the pot). It appears to be a 100k variable resistor from the 104 marking - are there recommended replacements? I presume the failure here is to do with the age of the board...

 

[zigzagjoe]

The variable inductor for width does not have an adjuster; it uses a hex tool to adjust. Avoid damage to it at all costs, as far as I know at this time it is irreplaceable as the value and parameters are not known.

Height is a 100K pot. I don't know if a exact replacement has been identified, though.

 

[PacificState]

Thanks! I did figure that out in the end, and I have the right tool handy. Per one of the clone board BOMs, I went with https://www.mouser.com/ProductDetail/531-PT10V-100K - I guess the alternative is to fix the original part, but it's a little concerning it fell apart under adjustment!