Bolex M8 Replacement Capacitor

[Bryan Chernick]

It's been a while since I posted here but I have a question about my Bolex M8 projector. I'm looking at replacing the capacitor but I'm having trouble finding the correct replacement. It's value is 400V 0.1uF. I believe it's polarized because it has a band on one side that would indicate the negative. Everything I have found with that value looks like non-polarized. I understand I can go up in voltage. I attached a photo, am I correct in assuming it's polarized? Can anyone recommend a replacement? I'm in the US so it runs on 110V.

I'm just going to remove the other capacitor. I understand it's just for noise suppression and isn't needed.

[Joerg Polzfusz]

Hi!

I haven’t got a clue when it comes to electronics. But browsing through the German online shops, the 400V capacitors are sold in two different sections: „Entstörkondensatoren“ (denoising capacitors) and „Motorkondensatoren“ (motor capacitors). Hence, I don’t know whether removing the capacitor will have a negative impact on the motor running smoothly (and hence a negative impact on your films).

[Steve Klare]

This looks like a motor capacitor, even if I do agree that the stripe on it looks like it isn't. The only other thing I could imagine is some kind of noise-suppression.

The good news is you can never get in trouble replacing a polarized cap with a non-polarized one (-the other-way around can get a little....lively, though!)

Here's a .1uF, 400 VAC (850 VDC) rated film capacitor which should drop in nicely.

Film Capacitor, .1uF 400VAC

It's also called "100nF" in places on the webpage. This is OK: "100 billionths" is the same thing as ".1 millionths"

It'll probably be smaller than the existing part: that's just technological progress. Just apply insulation where you need to to keep those leads off the chassis (-this goes double for a machine with a two-prong plug!)

[Bryan Chernick]

This looks like a motor capacitor, even if I do agree that the stripe on it looks like it isn't. The only other thing I could imagine is some kind of noise-suppression.

The good news is you can never get in trouble replacing a polarized cap with a non-polarized one (-the other-way around can get a little....lively, though!)

Here's a .1uF, 400 VAC (850 VDC) rated film capacitor which should drop in nicely.

Film Capacitor, .1uF 400VAC

It's also called "100nF" in places on the webpage. This is OK: "100 billionths" is the same thing as ".1 millionths"

It'll probably be smaller than the existing part: that's just technological progress. Just apply insulation where you need to to keep those leads off the chassis (-this goes double for a machine with a two-prong plug!)

Thanks Steve, that's very helpful, I'll order that one. I think it is the motor capacitor.

[Bryan Chernick]

It's fixed! works perfectly now. It wasn't the capacitor causing the problem, it was the speed control. Regardless, the capacitors needed to be addressed. first thing I did was remove the noise suppression capacitor, what I have read, it's no longer needed. Next, I replaced the motor capacitor with the one Steve told me to get. After that I tested it, still had the same problem, the speed was still low and surging. Next, I tried cleaning the speed control mechanism, it had a lot of corrosion. That didn't work so I took one of the coils out which released the metal bar that swings between them. filed off half a century of corrosion, smoothed it with steel wool, and put it back together. That fixed it. I'm so glad it's working again, this is my favorite projector.

Noise suppression capacitor removed.


New motor capacitor installed.



Cleaned speed control. I also rotated the coils slightly so the bar isn't rubbing on the same spot. You can still see a lot of corrosion on the coils. I tried gently cleaning it but it wouldn't come off. I was afraid if I got too aggressive I would damage it so I left well enough alone. You do have to loosen that center screw to take the coil off, then the bar just lifts off the post. I removed the one on the right since it has a longer wire allowing me to move it out of the way easier.