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

This is topic GS1200 : Upper Roller guide switch usefullness ??? in forum 8mm Forum at 8mm Forum.

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Posted by Phil Murat (Member # 5148) on 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 ?

Posted by Paul Adsett (Member # 25) on 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.

Posted by Phil Murat (Member # 5148) on 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

Posted by Phil Murat (Member # 5148) on 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.

Posted by Paul Adsett (Member # 25) on 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.

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