8mm Forum: Adjusting a sound head?

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Posted by Gary Baker (Member # 5862) on August 17, 2017, 04:24 AM:

Hi Folks,

Looking through the technical index, I couldn't find anything relating directly to this topic...

I recently shipped over a very nice example of a Kodak M100 to add to my growing projector collection (!). I have the service manual and with the right step-down transformer, have managed to get it running well. I'm really impressed with the machine and now just need to get the sound working properly to have a fully functioning model.

The sound does work but suffers from a distortion issue (almost like the film's running a wee tad slow, although the 24 fps image it's set at looks just fine.) I'm wondering if this is a sound head issue and if adjusting this might be all that's required?

On the other hand, is it possible that by stepping down from 240 to 110V the projector's not getting the precise electrical input needed to run at exactly the right speed? In which case, it's no biggie as this would then just become -hands down - the best silent projector I have.

If I were to investigate the sound head possibility, how is this best done? Do you expose the head's adjustment screws and then attempt a correction as the film is running? I have no experience in this area.

Any thoughts gratefully received.

Posted by Maurice Leakey (Member # 916) on August 17, 2017, 04:58 AM:

Gary
Before you do anything drastic, check the flywheel of the sound drum to see if it is revolving freely and not dragging.

Posted by Steve Klare (Member # 12) on August 17, 2017, 05:06 AM:

There's another possibility. If the machine has an AC motor the operating speed follows the frequency of the house current. Since you have 50 Hz power, if the machine is set for 60 Hz. North American house current you will run at 5/6 of the right speed even if the voltage is correct. This would take you to 20 FPS.

Very often an AC motored machine has some means of adjusting the speed up or down to compensate.

If it's a DC motored machine, you should be good to go already.

I've heard that head adjustment is usually something best left as the factory set it. It's very hard to get it right and once it's set loose and it's usually never as good as original again. To me it doesn't sound like something the heads being misadjusted should cause anyway.

This is a great machine, by the way. I hope you are able to overcome this!

Posted by Maurice Leakey (Member # 916) on August 17, 2017, 05:47 AM:

A good point made by Steve regarding British mains frequency as apposed to US, however, Van Eck's site says that the M100 has a DC magnetic motor.

You could check the M100s running speed at 24fps.

100ft of Super 8 sound film runs for 5 minutes, therefore 10ft would run for 30 seconds.

Take some scrap film and mark out an accurate length of 10ft. Warm up the projector first, and then run the film against a watch to see how many seconds it takes to run that length.

You can then calculate if it is running at 24fps.

Posted by Steve Klare (Member # 12) on August 17, 2017, 09:51 AM:

I saw that myself, but the single source of information makes me a little nervous, especially with such an unusual machine. (Nobody else seems to know.)

I know who to ask...

Posted by Gary Baker (Member # 5862) on August 17, 2017, 03:37 PM:

You guys were spot on. A closer inspection of the manual reveals this projector has an AC motor.

Will have to look into the possibility of adjusting the speed.

This makes me very happy as this thing's a beauty. I actually ran a silent cut-down version of Boris Karloff's 'The Mummy' for my ten year old daughter this afternoon accompanied by music from Alloy Orchestra's New Music for Silent Films - which I recommend - and, (rather gratifyingly) it kind of creeped her out (don't tell the wife).

Beautiful picture from this machine. I've just finished running a nice copy of King's Solomon's Mines and the colours have never looked better. With more careful viewing it's now clear to me that the image is indeed a little slow...about 4 frames worth, so you projector doctors have diagnosed correctly.

This gives me something to research and tinker towards.

Thanks! You are gentlemen and scholars. [Smile]

Posted by Paul Adsett (Member # 25) on August 17, 2017, 08:08 PM:

For Steve, and anyone else who has never seen the Kodak M100, here is a photo:

This is the projector that Kodak designed to showcase the new Super 8mm magnetic sound system on a professional quality projector. It is fitted with that superb, unbelievably sharp and flat field, fixed focus f1.0 Ektar lens. It had auto threading and a rotary knob which was used to totally remove the sound head from the film path for silent films. Lighting was 150 watt halogen with a high and low lamp setting switch. There was an analogue recording level meter and sockets for phono/tape/ microphone input. It has a big internal speaker housed in the wooden rear part of the projector. Plus, as you can see, it takes 1200ft spools. Picture quality, smoothness of running, and steadiness is better than anything I have ever seen on Super 8mm. The machine is built like a tank, being based on the superb 16mm Kodak Pageant design.
The down side is sound quality- not nearly as good as the 800 series Eumig's, and uses a hybrid valve/transistor amplifier. The sound head is brazed on to the end of a thin cantileverd metal finger, and adjustment would be extremely difficult. Kodak used to sell replacement sound head assemblies, which included the complex engagement mechanism.
But it's a stunner, Kodak's best ever S8 projector, designed and built in Rochester NY in the days before US corporations off loaded everything to the far east, when quality counted for something, and before Kodak became synonymous with cheap plastic projectors and cameras. Goes to show just how much Kodak and America has really lost in the last few decades.
Here is an ad for the Kodak Sound 8, which was a reg 8mm sound machine of similar design and build quality, which preceded the super 8mm M100 by a few years:

Those surely were the days!

Posted by Steve Klare (Member # 12) on August 17, 2017, 08:26 PM:

Thanks, Paul!

I'm interested in something on your machine, Gary. Please try to find a ratings plate. With an AC motor, if the plate says "50/60 Hz.", then there must be some internal adjustment to compensate for the motor speed. If it only says "60 Hz.", life is probably a little more complicated.

There are ways of providing 60 Hz. in a 50 Hz. place, but they aren't pretty!

(Just be glad it's not an electric clock: in a week you'd lose an entire day!)

Posted by Maurice Leakey (Member # 916) on August 18, 2017, 03:17 AM:

I have the similar 16mm Kodak Pageant model AV-12M6.
It took ages before I could find an export model that runs on 50 Hertz mains and had European voltage selection.

Posted by Gary Baker (Member # 5862) on August 19, 2017, 04:42 AM:

Found the plate in question and it states clearly: 100-125 Volts - 60 cycles - 3 Amperes.

Looks like I'm out of luck. It can be done it seems and I see there are options to make it happen but as, Steve said, they aren't pretty...

https://www.youtube.com/watch?v=_dgO0HdPMds

Posted by Steve Klare (Member # 12) on August 19, 2017, 06:13 AM:

Yes,

That's basically what I was thinking of. You'd also have to be careful to find an inverter that has a sine wave output. There are some out there with square wave that a synchronous motor would react pretty badly to.

Decades ago my parents and I camped at the local beach. There were no electrical hookups there back then. I talked them into buying an inverter and a deep-cycle marine battery. Being the only family in the place with electricity was kind of a treat! I also watched TV in the car on trips. My son just brings his iPad (-Too simple: where's the challenge?!)

Another way around this is to use a small UPS (like you'd use for computers). This is tricky too because you'd have to make sure that the output frequency was fixed at 60 Hz. I see a lot of them that are universal (50/60) input, which is in your favor, but if the manufacturer decided the thing should follow whichever frequency it encountered when it was first plugged in (which most users would want), you'd be pretty much back where you started, other than the money and time invested.

It would also need to be an off-line UPS, because the on-line ones just pass regular power through until there is a fault, which isn't helping you at all.

Even before all that, I think you'd be hard pressed to find a fixed 60 Cycle UPS in he UK. You'd probably have to import it, they have internal batteries and would be heavy to ship. (£££)

There are more ways than these. The sad part is these are the simpler ones!

So where there's a will there's a way, it just depends how much the will is willing to pay!

(It might be simpler to find a Canadian or American consulate in Glasgow and ask them if you can run an extension cord through a window!)

Posted by Maurizio Di Cintio (Member # 144) on August 19, 2017, 06:50 AM:

Please Paul: from the photo you posted, it seems to me the sound head assembly is past the second sprocket wheel... And no capstan/pinch roller (hence no flywheel! Is this correct???)

Thank you.

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