8mm Forum: GS1200 : Upper Roller guide switch usefullness ???

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Topic: GS1200 : Upper Roller guide switch usefullness ???

Phil Murat
Jedi Master Film Handler

Posts: 671
From: Villeneuve St Georges, France
Registered: Dec 2015

posted September 10, 2018 11:06 AM

Hello,

I have no idea of the use of it...... (On/Off, no change observed when projector is playing)
The micro switch is hidden in the upper "green" guide and actuated by the small lever with the roller....

Anybody has an idea ?

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Paul Adsett
Film God

Posts: 5003
From: USA
Registered: Jun 2003

posted September 10, 2018 01:39 PM

Phil, this micro switch is part of the front motor drive circuit. It is activated in reverse projection mode only, in order to reduce the rewind torque on the front spool, so as to avoid the film from slipping against itself ( ' cinching') while winding back up.

--------------------
The best of all worlds- 8mm, super 8mm, 9.5mm, and HD Digital Projection,
Elmo GS1200 f1.0 2-blade
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Panasonic PT-AE4000U digital pj

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Phil Murat
Jedi Master Film Handler

Posts: 671
From: Villeneuve St Georges, France
Registered: Dec 2015

posted September 10, 2018 02:04 PM

Hello Paul,

Thanks for this information, I'll make some tests again to observe these torque changing....

I let you know

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Phil Murat
Jedi Master Film Handler

Posts: 671
From: Villeneuve St Georges, France
Registered: Dec 2015

posted September 11, 2018 09:17 AM

Hi Paul,

After adjusting Both trimmers (Min & Max Torque) its's much better now.
It's strange both machines were showing same "defect".....(Max torque was a bit under rated).
Moreover these trimmers are poor quality and seem to lost continuity, so that , associated motor stop intermitently.
I have clean them with a good spray and it looks ok.

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Paul Adsett
Film God

Posts: 5003
From: USA
Registered: Jun 2003

posted September 11, 2018 11:00 AM

Phil, I think the microswitch is intended to reduce the reverse projection torque, mainly for the situation where you are using a small 200ft front reel (which has a small inner hub and therefore puts a lot of rewind tension on the film), which can cause film slippage and scratching.

--------------------
The best of all worlds- 8mm, super 8mm, 9.5mm, and HD Digital Projection,
Elmo GS1200 f1.0 2-blade
Eumig S938 Stereo f1.0 Ektar
Panasonic PT-AE4000U digital pj

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