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Author Topic: Critical: For GS 1200 Owners
Chip Gelmini
Phenomenal Film Handler

Posts: 1733
From: Brooksville, FL
Registered: Jun 2003


 - posted November 07, 2017 06:24 PM      Profile for Chip Gelmini     Send New Private Message       Edit/Delete Post 
ATTN: GS 1200 OWNERS

Okay this is a strange one.

Follow these steps. Note: Use caution. You need to have the volume very low. It is also done without film loaded. You should be throwing a white light only. Unplug any output cables and use only the built in speakers.

Begin test:

1. Use built in speakers.
2. Use track one volume control, set to less than “2” on the scale.
3. Put the projector in optical sound mode.
4. Put the projector in forward mode.
5. Turn on the picture lamp.
6. Drop down the front cover to expose film path.
7. Move your hand very close to the lens up and down very quickly.
8. Remember to have the sound down low, less than 2 on the scale.

WHAT IS THAT NOISE YOU HEAR? HOW IS IT CAUSED?

I am clueless and concerned. All of my GS1200 machines do this, and it would appear this should NOT be happening. Thanks for your suggestions.

I am trying to learn the nooks and crannies of these projectors. When I get one, I give them a head to toe kind of test - perhaps unlike anyone else probably does. And the problem I have described here does concern me. Because as far as I can tell, it's not normal for optical sound.

As your hand blocks the picture lamp in a sweeping motion following the steps above, you should hear a short blast that, well to put it bluntly, sounds like a light saber from Star Wars.

YIKES

End of test.

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Steve Klare
Film Guy

Posts: 7016
From: Long Island, NY, USA
Registered: Jun 2003


 - posted November 07, 2017 06:31 PM      Profile for Steve Klare   Email Steve Klare   Send New Private Message       Edit/Delete Post 
Hi Chip,

Do you think your hand is reflecting some of the light coming through the lens back onto the photo cell?

Put on some black gloves and see if that makes a difference!

I've noticed a similar effect on mag heads with my left hand but not my right. What's the difference?

-Wedding Ring!

--------------------
All I ask is a wide screen and a projector to light her by...

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Chip Gelmini
Phenomenal Film Handler

Posts: 1733
From: Brooksville, FL
Registered: Jun 2003


 - posted November 07, 2017 06:34 PM      Profile for Chip Gelmini     Send New Private Message       Edit/Delete Post 
Maybe. Did you try this yourself?

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Steve Klare
Film Guy

Posts: 7016
From: Long Island, NY, USA
Registered: Jun 2003


 - posted November 07, 2017 06:35 PM      Profile for Steve Klare   Email Steve Klare   Send New Private Message       Edit/Delete Post 
No, it's just a guess.

The only optical sound machine I own is my Kodak Pageant and I'm too tired (or maybe lazy) to lug it up the stairs!

It's wise not to do this through an amp and speakers. When I do things like that my wife asks "What on EARTH are you DOING?".

-some people don't understand the need to pursue new technical horizons! (Was Edison married?)

--------------------
All I ask is a wide screen and a projector to light her by...

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Thomas Knappstein
Expert Film Handler

Posts: 124
From: Erwitte, Germany
Registered: Oct 2017


 - posted November 07, 2017 10:29 PM      Profile for Thomas Knappstein   Email Thomas Knappstein   Send New Private Message       Edit/Delete Post 
This is commig from The AC voltaged Projection Lamp.
If The Light comes on the Cell for optcal Sound so it makes a Hum.
The Exiter Lamp is voltaged by DC so it works.

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Nantawat Kittiwarakul
Master Film Handler

Posts: 280
From: Rajburana, Bangkok, Thailand
Registered: Aug 2017


 - posted November 07, 2017 11:04 PM      Profile for Nantawat Kittiwarakul   Email Nantawat Kittiwarakul   Send New Private Message       Edit/Delete Post 
So something is bouncing the projected light (doesn't have to be from the lens,a spillover from the aperture will do) internally and finally landed it on the solar cell pickup,hence the hum? Saw that happening on another make&model before.

--------------------
Just a lone collector from a faraway land...

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Maurizio Di Cintio
Jedi Master Film Handler

Posts: 977
From: Ortona, Italy
Registered: Jan 2004


 - posted November 08, 2017 01:37 AM      Profile for Maurizio Di Cintio     Send New Private Message       Edit/Delete Post 
Hi, Guys! Steve is SPOT ON: it's light reflected onto the sound photocell. Nothing to worry about as in norma use, htis won't happen.

Just screen films, Chip, ANd enjoy your GS (though - of course! - it's wise to run test on it and check it thouroughly from time to time

--------------------
Maurizio

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Alan Rik
Film God

Posts: 2211
From: New York City, NY, USA
Registered: Jun 2003


 - posted November 08, 2017 02:43 AM      Profile for Alan Rik   Email Alan Rik   Send New Private Message       Edit/Delete Post 
This was critical? [Roll Eyes] Maybe it should be retitled as : Quirky:
I was worried there for a minute that all GS's leak cancerous gas or something...

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Brian Fretwell
Phenomenal Film Handler

Posts: 1785
From: London, UK
Registered: Jun 2014


 - posted November 08, 2017 02:45 AM      Profile for Brian Fretwell   Email Brian Fretwell   Send New Private Message       Edit/Delete Post 
Yes, at the Big Screen Scene Revival one optical sound projector gave a click from its speaker every time someone took a flash photo in the room. This, of course was before the show using it began.

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Chip Gelmini
Phenomenal Film Handler

Posts: 1733
From: Brooksville, FL
Registered: Jun 2003


 - posted November 08, 2017 06:50 AM      Profile for Chip Gelmini     Send New Private Message       Edit/Delete Post 
Alan that's a funny idea but I won't do it you know these projectors act up in the most strangest ways and I thought I had a serious problem but now I see I don't thank you all for your replies

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Chip Gelmini
Phenomenal Film Handler

Posts: 1733
From: Brooksville, FL
Registered: Jun 2003


 - posted November 10, 2017 10:51 AM      Profile for Chip Gelmini     Send New Private Message       Edit/Delete Post 
Hello everyone.

This is a follow up to the above mentioned optical noise when the picture lamp is blocked with the cover down.

As pointed out Steve Klare was right in his post about the diode picking up reflection.

The other night I tested a GS and placed my left pointer finger just behind the exciter bulb while blocking the picture lamp with my right hand and the problem was gone. My left finger blocked the light from reaching the diode further inside the machine.

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Chip Gelmini
Phenomenal Film Handler

Posts: 1733
From: Brooksville, FL
Registered: Jun 2003


 - posted December 03, 2017 09:32 AM      Profile for Chip Gelmini     Send New Private Message       Edit/Delete Post 
 -

Maybe this is something else I don't know. But food for thought anyways.

Well now, maybe we DO have a problem after all.

Read starting in top left corner. Follow the arrow down to the next block below it and the one below that..

Page 126 GS1200 service manual for the Version 1 machine (forward bottom loop)!

Quoting the manual:

Block 1:

Exciter lamp is lighting?

Block 2:

When lighting fluorescent to the solar battery, does noise come out?

Block 3:

Poor adjustment of exciter lamp and sound lens.

Now back in the day, I remember taking pictures of the projectors I ran in theaters. And of course, the camera flash would trigger a boom if the optical picked it up. That's only natural to happen.

But this buzzing sound with the GS1200 hand over the lens issue I think is more than that and should be addressed. It just doesn't seem right.

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Steve Klare
Film Guy

Posts: 7016
From: Long Island, NY, USA
Registered: Jun 2003


 - posted December 03, 2017 11:30 AM      Profile for Steve Klare   Email Steve Klare   Send New Private Message       Edit/Delete Post 
The buzz is probably because the light is pulsating from the shutter action.

It’s as if you fired the photo flash 72 times per second.

--------------------
All I ask is a wide screen and a projector to light her by...

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