8mm Forum: GS1200 Rewind

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Posted by Paul Adsett (Member # 25) on April 07, 2019, 12:36 PM:

Well never a dull moment with the GS1200! [Big Grin]

Yesterday I was rewinding a film on the GS when suddenly the rewind slowed down and came to a slow crawl. All the symptoms of aa burned out motor. I took the motor apart and inspected the commutator and windings and I could not see any damage like burned windings. I also re-cleaned the commutator and brushes(which I had done about a year ago) and re=assembled. I engaged the re-wind again and got the same slow crawl. Then I swiched to forward projection and observed that the motor was spinning normally (it runs during normal projection along with the rear take-up motor). This told me that the motor was OK, but it was not getting the proper voltage during re-wind. So it must be a circuit problem. No, it turns out to be a switch problem, namely the two micro switches that are activated when you pull on the re-wind knob. When I pushed on these by hand the rewind spun up normally with plenty of torque. So I continued to activate the micro switches on and off by hand and the problem has now gone away and rewid activation by pulling on the yellow slide bar is now normal. A case of dirty or oxidized contacts inside those micro-switches. If it happens again I will go in and replace these switches which should be a relatively easy job.
These micro switches seem to be all over the GS, controlling auto threading, lamp, rewind, and solenoids. In my experience they cause 90% of the problems I have encountered on my two GS1200's, and owners should expect that some of them are going to need periodic replacement.

Posted by Leon Norris (Member # 3151) on April 07, 2019, 01:20 PM:

Paul, You had it easy! I rarely had to replaced the rewind micro switches! I just kept them clean with contact cleaner with lubricant! For me the problem was the constant voltage control board! That also controls the rewind! I had to replace mine! They go! If the board is working right you should get better rewind! And better take up and reverse! So keep a eye on it!

Posted by Lee Mannering (Member # 728) on April 08, 2019, 12:39 AM:

Those little micro switches are a pain and not just unique to Elmo GS1200's. My rule of thumb is when one goes change them all for new ones. Having a few GS machines I got fed up with one going then using another machine and then another. In the end I spent a happy weekend fitting new switches to them all and zero trouble since. Serviced a friends recently same thing Micro Switch. Grrr

Tis worth remembering these old girls were introduced as early as 1978 so we are looking at a good few decades of age and use.

Posted by Steve Klare (Member # 12) on April 10, 2019, 10:24 AM:

Yessir!

-a few years ago I replaced one switch on one of mine.

Eventually I will pay for it too!

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