8mm Forum: Elmo GS 1200 Projector

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Topic: Elmo GS 1200 Projector

Alex Fox
Expert Film Handler

Posts: 179
From: Vineland Ontario Canada
Registered: Jul 2003

posted June 06, 2005 12:34 PM

Hi I'm getting a lound hum from one of my projectors,would any of gents out know of this problem and is there a fix for it ALEX

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Rick Skowronek
Expert Film Handler

Posts: 120
From: Marietta Georgia USA
Registered: May 2005

posted June 06, 2005 01:10 PM

Hum like from the audio? If audio, does it vary with the volume control or always stay the same?

If not the audio, is it when the projector is running, etc.?
Also, make and model may be helpful. Oops, saw your heading as Elmo GS1200. Got many great gurus here on that model.

Rick

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Alex Fox
Expert Film Handler

Posts: 179
From: Vineland Ontario Canada
Registered: Jul 2003

posted June 07, 2005 03:53 PM

Hi RICK, Thank you for your reply, yes it is from the audio when I turn up the volume the hum gets louder ALEX

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Rick Skowronek
Expert Film Handler

Posts: 120
From: Marietta Georgia USA
Registered: May 2005

posted June 07, 2005 06:29 PM

Alex,

Pretty much sounds like the amplifier power supply filter capacitor. Again, I defer to Kevin Faulkner and the others that own these beautiful pieces of machinery. Though it could be other things, those are the most susceptible to aging and failure.

Might suggest you do one other thing and that is put the unit into a playback mode and cycle the record switch on and off at least 10-15 times to insure it isn't creating an open head ground situation. Record isn't used much and as such the switches, with age, wont make contact as well as they used to when new.

This is something you should do after 4 or 5 reels (or so) anyway.

Hope the other GS 1200 owners chime in for you.

Rick

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Mark Todd
Film God

Posts: 3846
From: UK
Registered: Aug 2003

posted June 08, 2005 03:30 AM

Hi usually if you turn the tone up higher( bass down) it helps reduce it quite a bit, for the time being.
You can find varius models of the same machine some will have more hum than others.
A low recorded sondtrack will show it up more than a high one.
Best Mark.

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John Clancy
Phenomenal Film Handler

Posts: 1954
From: Cornwall
Registered: Jun 2003

posted June 08, 2005 08:11 AM

Possibly the two pots by the sound head have been knocked out of their preferred position (different for every machine) and require playing with to find their best location to minimise noise.

--------------------
British Film Collectors Convention home page www.bfcc.biz. The site is for the whole of the film collecting hobby and not just the BFCC.

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Kevin Faulkner
Film God

Posts: 4071
From: Essex UK
Registered: Jun 2003

posted June 08, 2005 12:22 PM

Yes John, I think thats the more likely. Nearly all the Elmos I have ever seen can be made quieter by adjusting these two coils. My theory is that when they are set up in Japan its probably not using the same voltage and frequency as we do in other parts of the world. These coils are for hum cancellation and the way to adjust them is to put the projector in forward play with the lamp on the full setting and with the vol control for the left track up full with the bass also full. It does help to put the machine to mono as the hum usually gets louder.
Now use a non mettalic item such as a plastic knitting needle and tap each of the 2 coils which are situated directly under the heads on a small pcb. One coil will amplify the tapping sound through the speaker. When you have found the correct coil gently move it about to give the least hum.
After you have done this turn down the left vol and turn up the right vol control and then adjust the other of the two coils. This should now give the lowest hum levels possible on that machine.
This method works on all the Elmo sound machines, even the single track mono machines.
One word of caution: Be careful moving these coils and dont be to heavy handed with them as the wires can snap off where they enter each end of the coil. Be gentle.
Most movie projectors with Mag sound have some sort of coil arrangement for this purpose.

Kev.

[ June 11, 2005, 12:07 PM: Message edited by: Kevin Faulkner ]

--------------------
GS1200 Xenon with Elmo 1.0...great combo along with a 16-CL Xenon for that super bright white light.

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Rick Skowronek
Expert Film Handler

Posts: 120
From: Marietta Georgia USA
Registered: May 2005

posted June 08, 2005 01:11 PM

Aha, that's what those two inductor coils on the heads are for on the schematic. Cool. My power supply suggestion would probably not be correct as the bridge rectifier without proper filtering would create more of buzz than a hum (50 or 60 Hz hum vs. the rectified 100-120 Hz buzz). The wealth of knowledge here is amazing. Learn something new everyday.

Rick

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Alex Fox
Expert Film Handler

Posts: 179
From: Vineland Ontario Canada
Registered: Jul 2003

posted June 09, 2005 01:16 PM

Hi I wish to thank you gentlemen for taking the time to answer my queery with regards to the problem that I am having with the GS1200.I WILL LOOK INTO EACH ONE AND SEE WHAT I CAN CME UP WITH ALEX

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