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Author Topic: Potts Platter Takeup/Payout Problem Patrick Matthews Film Handler Posts: 86 From: Kansas City, MO, USA Registered: Sep 2004 posted 12-29-2009 11:27 AM                     My Potts Platter is quickly becoming unreliable. I have narrowed it down to the variac. It seems that it will no longer engage the motors when the take up plate is pinned. This is usually the area that the take up plate hovers at during normal operation. Now it seems like that area is about 1/2"-1" below where it should be causing the motors to not engage when they should and then spin too fast when they do. So, is this the brush going bad on the variac motor or do I need to reset electric zero with the variac hub?  |  IP: Logged Kirk Futrell Film Handler Posts: 95 From: Nashville, TN / U.S.A. Registered: Nov 2008 posted 12-29-2009 12:00 PM                        Make sure the button switch on the variac isn't gummed up. Remove power to the variac and spray the switch with contact cleaner and push the button several times. You may even want to lightly lube the switch so it travels in and out smoothly. Also make sure that all the bolts and screws holding the variac arm together are lubricated and properly tightened, so the angled plate that hits the button switch on the variac does so at the correct time. This worked for me when I had a similar problem, of course the problem you are experiencing may be less superficial, in which case I can't help.  |  IP: Logged Monte L Fullmer Film God Posts: 8367 From: Nampa, Idaho, USA Registered: Nov 2004 posted 12-29-2009 12:32 PM                     quote: Patrick Matthews So, is this the brush going bad on the variac motor or do I need to reset electric zero with the variac hub? I've seen brushes go bad - both the button and the brush itself..have you tried to reset to electical zero yet?  |  IP: Logged Paul J. Neuhaus Expert Film Handler Posts: 126 From: Iraq.. Again! Registered: Jun 2005 posted 12-30-2009 03:39 PM                     Probably the zero. But, I agree with the above about a good cleaning. Things can get jarred out of place in time. Think about it everytime a show ends the variac arm slams to the bottom. You're headed in the right direction.  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 12-30-2009 04:17 PM                     YEp! Check the rotor brush... not the ccarbon one but the one near the center of the variac. The contact tends to snap off leaving the end of the brass arm rubbing on the rotor and then things run really erratic. Matrk  |  IP: Logged Monte L Fullmer Film God Posts: 8367 From: Nampa, Idaho, USA Registered: Nov 2004 posted 12-31-2009 01:01 AM                     I've had to replace three variacs on Alpha platters due to the same button wear on the rotor. You can really see the "Christmas lights" effect where that variac is mounted when that button is worn off .. and horrible platter action.. I think that you can replace that rotor instead of buying a new variac. Pair of external snap ring pliers removes the ring attached to the rotor, which will remove the rotor from the frame. Check with your supplier on this option - this has to come from STRONG. -Monte  |  IP: Logged Patrick Matthews Film Handler Posts: 86 From: Kansas City, MO, USA Registered: Sep 2004 posted 12-31-2009 10:40 AM                     Ok, checked electric zero and that wasn't the problem. So I obviously have a bigger one. I don't have much (read any) experience working the the variac. I have one totally intact that was removed by a tech a few years ago and I'm trying to take it apart to see what we are talking about before I go ripping the active one apart. I'm having trouble getting, what I guess is, the transformer out to get a better look at the brushes and whatnot. I can't seem to remove it from the casing because of the variac shaft, I'm assuming. Can anyone help me out? Sorry for my lack of knowledge, but I'd like to try to get it fixed myself than having to drag a tech down here.  |  IP: Logged Louis Bornwasser Film God Posts: 4441 From: prospect ky usa Registered: Mar 2005 posted 12-31-2009 11:11 AM                        As Monte mentioned, remove the shaft (set screws on "wrong" end) and then disassemble shaft using the ring-removal tool. Now that the holidays are behind us, you could also ship the variac to one of us for repair. The part you need: the contact and contact plate are easy to deal with once you gain access. louis  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 12-31-2009 05:49 PM                     Be wary of using the one the tech removed... it must have been removed for a reason... and why did he not repair it? Parts are cheap and available through STACO Energy Products or W.W. Grainger.  |  IP: Logged

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