8mm Forum: Elmo GS 1200: ESS mode is not working

This is topic Elmo GS 1200: ESS mode is not working in forum 8mm Forum at 8mm Forum.

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Posted by Rene Ruppert (Member # 5392) on September 06, 2019, 11:41 AM:

After fixing the take-up arm of my “new” GS 1200 (first version) I noticed a problem with the ESS mode. I tried to run the Elmo by feeding a sync signal for the first time (usually I use my Braun Visacustic for re-recordings). I’m using a self-made cable with RCA und DIN plugs - signal on pin 4 and ground on 5, as described here:

http://8mmforum.film-tech.com/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=1;t=001956;p=1

The problem is that the projector – which is set correctly to the “ESS” mode – does not react to the sync signal. Even the pulse level doesn’t show any reaction, the needle isn’t moving at all. I tried two different 24Hz square signals (generated with Audacity and Audition) and tried to play from a BD player (RCA out) and a notebook (headphone output) – without success.

Is there anything I could try to get the machine working?

Posted by Phil Murat (Member # 5148) on September 06, 2019, 01:13 PM:

Hello Rene,

From my side , I use a Synchro-Box (Home Made) which shows an adjustable "Pulse Gain" and gives a very good square signal.

You increase gain untill projector starts.

Then it is also recommended to use short shielded cables with good connectors.

Moveover, in case "ESS" sliding switch is sometime faulty , you can soak it with a powerfull contact cleaner (spray gun)

Posted by Rene Ruppert (Member # 5392) on September 06, 2019, 01:19 PM:

Hello Phil,
Thanks for your answer! I'll try to clean the switch tomorrow.

Posted by Rene Ruppert (Member # 5392) on September 07, 2019, 04:24 AM:

Today I tried again and besides cleaning the ESS switch I raised the level of the sync signal with an amplifier. The needle of the pulse level reacted at once and the projector started. I played a film for testing and the Elmo ran perfectly in sync with the digital sound. So it seems that the Elmo needs a "stronger" signal than my Visacustic.

Posted by Phil Murat (Member # 5148) on September 07, 2019, 11:56 AM:

Hi Rene,

Thanks for these informations.
A powerfull signal to run the Elmo GS1200 prevent you from unwanted mahine starts or synchro faults due to external frequencies polution (Ex : power frequencies, any radio waves, etc....)
Once more, best quality shielded cables are recommended.

Posted by Paul Browning (Member # 2715) on September 07, 2019, 02:13 PM:

Rene, there was something about the capacitor on the board drying out, generally due to not being used for a period of time. I looked for in the tech info but its not there. I have generated square wave signals like you with audacity and run it straight into the gs from the computer with no problem with the levels, so it could be this capacitor at fault.

Posted by Rene Ruppert (Member # 5392) on September 07, 2019, 02:40 PM:

Hi Phil and Paul,
Thanks for your support! Today I re-recorded two reels of a Derann feature and the sound was in perfect sync. The capacitor may have dried out, but as long as the "workaround" helps, it's o.k. with me.
But when I checked the recording, I noticed a high-frequent noise on both tracks which appears towards the end of the reels. When I got the projector, this noise was present during playback - pressing the recording buttons a few times helped. I read about a capacitor that's well known for making trouble during recording (when it gets hotter?). But soldering on the circuit board goes beyond my abilities ...

Posted by Phil Murat (Member # 5148) on September 07, 2019, 11:26 PM:

Hi Rene,
Due to possible High frequencies crossing them, I suggest you to replace mentionned capacitors by 2 capacitors (same voltage but half capacity) installed in "parallel assemblies" at the same place to decrease impedance.
So that Capacitors stress is significantly decreased.

Posted by Rene Ruppert (Member # 5392) on September 08, 2019, 01:56 AM:

Hi Phil,
I'm afraid this hobby requires either a degree in electrical engineering or a specialist workshop in the neighborhood. Unfortunately, I have neither. ;-)
Maybe I find an engineer who can do the job. I do not want to kill the machine while repairing.

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