Film-Tech Forum ARCHIVE: Potts platter motor problems

This is topic Potts platter motor problems in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Louis Belloisy (Member # 3836) on 09-14-2009, 08:49 AM:

Hi, my main problem in our booth (6 screens) is the older Potts platter motors. I have rebuilt them over the years using parts from scrapped motors. I have two motors that run too fast. No matter how i try to adjust them, they will try to sling the film off the platter during the latter part of the film when it gets lighter.

The motor consists of the normal motor workings plus a diode and a large resister. would either of these components cause the speed problem. any help would be appreciated.

louis

Posted by Mark Gulbrandsen (Member # 72) on 09-14-2009, 09:03 AM:

The diode is there in payout to cut the voltage in half essentially so if this is a timming problem the diode is probably ok. One time long long ago Bob Potts did send me some higher ohm resistiors to cut speed down on some motors. It worked ok. There is also smaller diameter sleeve available that interchanges with the present sleeve for the fast running motors. Did you install new brushes???

Mark

Posted by Gordon McLeod (Member # 33) on 09-14-2009, 10:33 AM:

Mark said "The diode is there in payout to cut the voltage in half essentially"
It is in line all the time the resistor is switched in and out

Posted by Louis Bornwasser (Member # 3063) on 09-14-2009, 11:02 AM:

#1 level the offending platters

#2 buy Brad's platter kit that keeps from slinging film.

#3 adjust the feed out switch to minimize wrapping. (Pull the switch as far away from the actuator arm as you can.)

Normally the correct operation of the microswitch will minimize the start/stop into a fast/slow.

Good Luck. Louis

Posted by Louis Belloisy (Member # 3836) on 09-14-2009, 06:22 PM:

Thanks everyone, yes i did change the brushes.

i will try the adjustment of the switch.

thanks,

louis