Source for brightness pot for SE analog board?

[polpo]

I’m trying to fix no video on this Macintosh SE/30 that looks like got dropped on its front left corner. The brightness pot is pretty smashed up and reads as an open circuit on my multimeter. Does anyone know if this is a common part that’s still available today, or if there are any substitutes?

Oh, and bonus pic of the screen describing its current state!

 

[polpo]

To kinda answer my own question, after measuring an un-smashed pot on another analog board, this Alpha potentiometer, part number 3RP/1612N-AA2-B1M seems to be the closest match. Of course, I can't find any place that actually stocks it.

I'm assuming I want linear taper, not audio taper for the brightness control. If audio taper, the suffix is -A1M.

I may try to find one with the same 18MM height from board to center of shaft, but without the extra support legs on the back. Since the front of the knob is supported by the Mac's case, it may not need such a beefy connection to the analog board.

 

[ScutBoy]

If you find a good solution - or if anyone has otherwise munged up boards and can spare them - I could use a couple as well!

@polpo should get first dibs, though!

 

[polpo]

I've been unable to find an exact replacement so far. I've tried using this other Alpha pot: https://www.taydaelectronics.com/b-1m-ohm-linear-taper-potentiometer-spline-shaft-pc-mount.html
It has the right lead spacing and body size, but has a few downsides: the leads have to be bent straight and trimmed to match the original pot's height, and it has a spline shaft instead of a D shaft. I've filed the shaft down with a dremel and wrapped it with tape to get the right thickness, but it's not exactly centered so the knob wobbles when turning. The knob also doesn't push onto it all of the way without trimming some plastic from its interior, which I'm reluctant to do on increasingly rare parts.

I've found that I tend to not adjust the screen's brightness much, so an ~18kOhm resistor works just fine in place of the potentiometer. It's a resonable long-term solution for me!

 

[speakers]

I've been unable to find an exact replacement so far. I've tried using this other Alpha pot: https://www.taydaelectronics.com/b-1m-ohm-linear-taper-potentiometer-spline-shaft-pc-mount.html
It has the right lead spacing and body size, but has a few downsides: the leads have to be bent straight and trimmed to match the original pot's height, and it has a spline shaft instead of a D shaft. I've filed the shaft down with a dremel and wrapped it with tape to get the right thickness, but it's not exactly centered so the knob wobbles when turning. The knob also doesn't push onto it all of the way without trimming some plastic from its interior, which I'm reluctant to do on increasingly rare parts.

I've found that I tend to not adjust the screen's brightness much, so an ~18kOhm resistor works just fine in place of the potentiometer. It's a resonable long-term solution for me!

I'm fixing up an SE/30 and my brightness pot has also been munged. In my case, ~180KΩ is the value needed for adequate brightness. Your 18KΩ seems very low (for a 1MΩ pot) - was this a typo?

My SE/30 also had a arcing CRT due to it the nipple breaking at the end of the neck and hence bye-bye vacuum. The arcing also took out Q1 on the CRT circuit board but luckily that seems to be the extent of the frying and I even happened to have the exact replacement on hand!

I haven't decided yet whether to fix the brightness at 180KΩ or to craft a bespoke pot as you did.