8mm Forum: Repair my Elmo GS1200

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Posted by Antoine Orsero (Member # 41) on April 09, 2018, 08:49 AM:

One of my two projectors ELMO GS1200 has a problem with the sound. Significant noise from clicks ... especially in optical sound
I had in reserve a spare part disassembled from an old projector broke down! An amplifier (see photo) and I did not know if it was in working order. So I removed the defective amplifier from my current projector and I replaced it with the one I had in store! But before I cleaned all the contacts with a special product!
I'm happy because not only I no longer have these parasites in the sound but in addition the optical sound is quite powerful.
It is important to buy used parts when they are put on sale on the web

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Posted by Joe Taffis (Member # 4) on April 09, 2018, 08:59 AM:

Nice work Tony! I also keep many spare parts for my projectors and editor [Smile]

Posted by Clive Carmock (Member # 347) on April 12, 2018, 02:27 PM:

Sounds a good repair. Another thing to watch out for on GS1200's with optical sound, particularly in dry weather is static build up on the capstan. It affects Xenon versions of the machine mainly though. The non Xenon machine has a copper earthing/grounding strap touching the tip of the capstan in the back of the machine and grounding it to the chassis. Later Xenon machines had an extra transformer in that position to increase voltage to the fan to increase airflow.

In that version of the machine this copper strap is not there, and so static builds up on the capstan and will actually discharge with small sparks. This doesn't affect magnetic playback, but the optical pickup 'sees' the spark and you hear a click or crackle on the sound.

When the weather is more humid you don't get that, but when dry you do, so watch for that as well.

On the amplifier board you show in your picture is a resistor which if cut boost the volume of the optical playback. Elmo seemed to think it needed this resistor to lower optical volume slightly.

Posted by Melvin England (Member # 5270) on April 12, 2018, 05:46 PM:

Clive - On the non Xenon versions, is this the cause of the rumbling I can hear on the optical soundtrack which interferes with the sound quality particularly on quieter scenes? I always thought that it was a fading optical signal from the print as it gets older. Is there a remedy?

Posted by Antoine Orsero (Member # 41) on April 13, 2018, 08:15 AM:

Clive,

Thanks a lot for the clarifications! You talk about a resistance in my picture. But I do not see it. Where is she? And if this resistance is cut off as you write, does this break not affect the magnetic reading?

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