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Author Topic: Run Capacitor ?? Don Sneed Master Film Handler Posts: 451 From: Texas City, TX, USA Registered: Aug 2001 posted 06-01-2002 12:44 PM                        Here is a question I should know but don't...I know what the start capacitor does, but what does the run capacitor do ?? I was in north Dallas & service an old GCC theatre which is now a Cinema Grill theatre that has Cinemeccania V-5 & V-8 projectors, I had trouble with the motors running, I checked the start & run capacitors & found ok, problem was in the wiring (Long Story) but I repaired the wiring & all is OK now...not being use to the V-8 proj. just wondering what does the run cap. do after the motor start ???  |  IP: Logged Jan Hackett Expert Film Handler Posts: 148 From: Albuquerque, NM, USA Registered: Apr 2002 posted 06-01-2002 12:55 PM                     maybe keep current stable during show run trapping nonwanted variace to ground? ------------------ Jan Hackett Theater Operations Manager Extreme Screen Dynatheater NM Museum of Natural History Foundation  |  IP: Logged Josh Jones Redhat Posts: 1207 From: Plano, TX Registered: Apr 2000 posted 06-01-2002 01:31 PM                        Perhaps they delay the phase for startup? I'm not sure either.  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 06-01-2002 01:58 PM                     The cinemecanica all have 3 phase motors and the run capacitor creates a phantom 3rd leg for the motor A 3 phase motor will run without it once spinning but will run hot and with less torque Often the start cap value and the run value will be different dpending on the morot design The Prevost 3phase machines all use the same value for start and run  |  IP: Logged Steve Kraus Film God Posts: 4094 From: Chicago, IL, USA Registered: May 2000 posted 06-01-2002 10:18 PM                    If it's a single phase PSC motor there is a 2nd winding which is the one connected to the capacitor. This creates a phase shift on the 2nd winding and that difference is what drives the motor. But since you're talking Cinemeccanica then Gordon's answer about 3-phase motors applies.  |  IP: Logged John Walsh Film God Posts: 2490 From: Connecticut, USA, Earth, Milky Way Registered: Oct 1999 posted 06-01-2002 11:03 PM                     Yeah, the V8's orginally had a funky "power on" switch. There were two sections to the toggle you pushed down on. When you pushed down, you were supposed to hold it for about 1/2 a second, then let up, ie: you were the "timer". The outer section came up, but the inner section stayed down, keeping the motor running. I had a little laugh when the installer came to change the two projector c/o booth I worked into a twin. (Each projector was set up with a platter and automated.) I told him that he couldn't just put a relay accross the motor switch on the V8; that some kind of timer was needed to mimic that switch, to get the motor going. He thought I didn't know jack and said something like; "Yeah, sure, thanks kid." I ended up designing a little circuit for him.  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 06-02-2002 01:10 PM                     I had a similar problem with an electrician who went and skipped the timer on the starting resistors on the 3 phase VIc8's and %'s in one complex and wouldn't listen wiht in a month all the shutter gear boxes had to be replaced  |  IP: Logged

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