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Author Topic: Potts Platter Take-Up Problem Patrick Matthews Film Handler Posts: 86 From: Kansas City, MO, USA Registered: Sep 2004 posted 12-23-2005 10:43 AM                     After getting a new brain and it not doing the trick when it came to irregular payout I have come to the conclusion (based on the fact that it happens to every deck so it probably isn't the motor brushes) that is has something to do with the take up system. I sat and watched as I ran a test reel today I noticed that the area that the take-up mechanism is able to engage the motor is a lot smaller than it used to be. This is to say that at the majority of points from the most northern part to the most southern part have the motor disengaged rather than engaged, leading to a very unsteady take up (the tree is never "level") Is there an easy adjustment for this?  |  IP: Logged Steve Scott Phenomenal Film Handler Posts: 1300 From: Minneapolis, MN Registered: Sep 2000 posted 12-23-2005 12:00 PM                     The start/stop points on the take up variac are probably dirty or out of alignment. Pull the power plug to the platter & inspect it, if you have another Potts, compare its settings to the malfunctioning one & set accordingly.  |  IP: Logged Patrick Matthews Film Handler Posts: 86 From: Kansas City, MO, USA Registered: Sep 2004 posted 12-23-2005 12:02 PM                     I talked with a tech guy that our owner knows (our tech is out of the country) and he said that I need to set the "Electronic Zero". He is faxing over instructions. Is this a hard procedure?  |  IP: Logged Monte L Fullmer Film God Posts: 8367 From: Nampa, Idaho, USA Registered: Nov 2004 posted 12-24-2005 02:43 AM                     Loosen the motor bracket bolts and raise the motor, or lower the motor a bit to find that "sweet spot". This is how one adjusts the takeup tension and adjusts the platter RPM.  |  IP: Logged Dustin Mitchell Phenomenal Film Handler Posts: 1865 From: Mondovi, WI, USA Registered: Mar 2000 posted 12-24-2005 02:53 AM                     The platter 'drive tires' might need to be replaced too. These are the two rubber rings that actually make contact with the deck.  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 12-24-2005 09:46 AM                     quote: Monte L Fullmer Loosen the motor bracket bolts and raise the motor, or lower the motor a bit to find that "sweet spot". Monte, What does this have to do with finding the zero voltage point? Setting the zero voltage point is easy. Remove the variac cover and loosen the set screw in the center of the variac shaft to loosen the clamp(some older platters have two allen head screws there). Place one deck in "take up", then with the take up "tree" at a point that the microswitch is just not being activated be sure that the variac is not allowing any platters to turn at all. If the deck is turning just turn the variac shaft counterclockwise so the deck just stops. Then tighten down the locking screw(s). Your platter is now set for zero voltage with the tree at its lowest OPERATING point just before the microswitch turns off the power. Also.... while you have the cover off take a flashlight and check the variac brishes, not so much the stator carbon brush as they rarely wear out but in particuluar the center rotor contact to be sure that its not worn out and also that its not broken off. There should be a contact button seen in there at the end of the piece making contact with the coppper area on the rotor. Broken center rotor contacts are quite common and will cause very erratic operation. Some platters will run for a long time with a broken rotor contact but will eventually wear through the copper ring on the rotor that it makes contact with. Then all hell breaks loose. Hope this helps.... Mark  |  IP: Logged Aaron Mehocic Jedi Master Film Handler Posts: 804 From: New Castle, PA, USA Registered: Jun 99 posted 12-24-2005 11:50 AM                     quote: Dustin Mitchell The platter 'drive tires' might need to be replaced too. These are the two rubber rings that actually make contact with the deck. Use Kirby vacuum cleaner belt K-159056 for best results (not kidding). I ordered a whole bag full last year from our local mom-and-pap sweeper store and got a substantial discount on each belt. Changing the belts is a simple task and can be done in between shows. Two signs that belts need changed are shuttering decks and uncentered prints (usually resulting in thrown prints).  |  IP: Logged Monte L Fullmer Film God Posts: 8367 From: Nampa, Idaho, USA Registered: Nov 2004 posted 12-24-2005 12:46 PM                     HI Mark. I had a hunch that "electronic zero" IS the variac adjustments needed in the control arm in the control box, but to be safe thought I just chime in on the motor adjustment thingey to sorta help out.  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 12-24-2005 02:46 PM                     Just don't want him to get confused over which is which.... you left it sounding like the motor height afjustment had something to do with the zero voltage adjustment. Mark  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 12-24-2005 06:27 PM                     And be very carefull on some variacs the metal plate that holds the brush is live. Autotransformers under dead short conditions can act like a choke and current limit themselves so fuses don't blow and if they do they can provide a nasty kick from the collapsing field If you are not sure of the correct sfety methods then call in your service engineer  |  IP: Logged Dustin Mitchell Phenomenal Film Handler Posts: 1865 From: Mondovi, WI, USA Registered: Mar 2000 posted 12-25-2005 01:18 PM                     Mark, is the Potts platter take-up that different from the Alpha platter take up? Either I'm mis-reading your post or you have your instructions backwards. When I read it it sounds like you're saying to set the take up assembly as low as it will go without tripping the microswitch. But on the Alpha platter you have to do the opposite-set is as high as it will go. From the Alpha manual (the Potts manual doesn't have instructions for setting the variac in it): 1) Raise the take up to the top of its travel and secure there with a rubber band around the pulleys..... (further instructions in the manual found in the manuals section of this site)  |  IP: Logged Monte L Fullmer Film God Posts: 8367 From: Nampa, Idaho, USA Registered: Nov 2004 posted 12-25-2005 01:47 PM                     I had to do a couple of Alphas and I've done it with the accumulator in the down postion to get things centered and microswitch adjusted correctly (course, unplug the platter first from the wall..lol) in the variac box. Not so sure on the Potts, but if like the Balco with that cable drawn variac to the accumulator, it could be the same as the Alpha.  |  IP: Logged Dustin Mitchell Phenomenal Film Handler Posts: 1865 From: Mondovi, WI, USA Registered: Mar 2000 posted 12-25-2005 02:56 PM                     On an Alpha the electric zero should be at the top. Why would it be at the buttom-that's what the microswitch is there for.  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 12-25-2005 02:59 PM                     The platter should be set for zero with the dancer in the top position  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 12-25-2005 03:27 PM                     You guys are right... caught me with my pants down ! Merry Xmas! Mark  |  IP: Logged

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