This is topic Prevost 16mm P78 motor problems in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.


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Posted by Paul Gordon (Member # 3320) on 03-21-2008, 10:36 AM:
 
Not sure if anyone can help but heres the problem...

I'm helping install a couple used projectors in a small non-profit screening room.. The 35mm install is all good and working but the 16mm has issues. The projector is a Prevost p78, 220 volt single phase 60 hz w/ 6000ft reels. It was wired up on two 30 amp breakers and a dryer style 220 volt plug was installed on it. The thing powers up, fans go, lamp strikes (500 watt Xenon) and the rewind/take up motor goes, but not the projector motor? We tested it before moving it and it ran fine. The Intermittent turns over by hand. When you turn the switch for the motor all that comes on is the take up motor. I'm going to have to trouble shoot the thing as all the cables seem wired fine...any help would be great, as they want this thing going for a screening next Saturday. Thanks

[ 03-21-2008, 05:12 PM: Message edited by: Paul Gordon ]
 

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Posted by Richard Fowler (Member # 893) on 03-21-2008, 01:51 PM:
 
Are you using two separate breakers or a double pole to get you single phase 220VAC??
 

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Posted by Jeff Taylor (Member # 443) on 03-21-2008, 02:28 PM:
 
Seems unlikely if the lamp is striking, but Richard has a point in that theoretically with two breakers you may have two feeds of the same leg rather than two legs for 220.
 

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Posted by Paul Gordon (Member # 3320) on 03-21-2008, 05:01 PM:
 
A city electrician did the wiring for the outlet. Looking at the breaker box its wired to, two 30 Amp breakers. Is that correct?
 

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Posted by Richard Fowler (Member # 893) on 03-21-2008, 05:54 PM:
 
City electrician.... Was he on hand to check performance after hook up or given the correct information. Most North American panels for 208-230VAC will have a two pole breaker taking up two space horizontally to grab two different electrical legs. Single pole 30amp @ 110VAC are becoming more in use due to more recent video projectors running 20 + amperes for input. If this is a Prevost wired up by Xetron, it could have a mix of 110 and 220 VAC components. It is possible if you do have proper single phase power that the motor connections to switch via motor starter kit (if required by the type of motor) to fuses to projector terminal board may have been disturbed....type of motor via information on motor would help.
 

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Posted by Paul Gordon (Member # 3320) on 03-21-2008, 06:14 PM:
 
The screening room is in a city building, so a city electrician had to do the wiring, but he was not around for the install. It took us two months just to get the electrician to show up! Anyway I'll track down the manual for the the projector to find out the motor specs. All the power comes in from a single 220 volt cable, he mounted a dryer style outlet on the wall so you could plug the projector in rather then having it hard wired. The projector was from a Cineplex Odeon back in the late 70's early 80's when they ran 16mm reduction prints in their tiny multi-screen cinemas ,Eaton center in Toronto and cinemas in Ottawa (which this one was originally from) There is no specs written on the motor but on the back of the lamphouse its says, 220volt, 60hz, 5 amps.

Thanks for the help..
 

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Posted by Gordon McLeod (Member # 33) on 03-23-2008, 05:37 PM:
 
All the prevost motors are 3 phase and in the cineplex machines they use a run capacitor from one leg to create a 3rd phantom phase
The takeup torque motor us also the same design and uses seperate relays and capacitors
Often there were problems with the switching especially the micro switch that sensed takeup tension
 

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Posted by Richard Fowler (Member # 893) on 03-24-2008, 07:48 AM:
 
Gorden hit a point....I have worked on many 16mm Prevost with film run out / tension switches to shut down the motor.
 

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Posted by Paul Gordon (Member # 3320) on 03-25-2008, 06:01 AM:
 
We got it working...it was the micro switch and the fact that the motor was not engaging the gear correctly. We took it off and reset it, everything is up and running. While we are at it... one of our roller pads needs replaced, its rubber padding is all cracked, its just above the sound head used its used to adjust the tension of the sound head. Does anyone still make parts for this thing, or have parts?


 

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Posted by Sean McKinnon (Member # 612) on 03-25-2008, 06:11 AM:
 

quote: Gordon McLeod

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they use a run capacitor from one leg to create a 3rd phantom phase

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Didn't Cinnemacanicca (sp?) do the same thing with the V4? I had an emergency call one day where the theatre thought the motor needed to be replaced and had one shipped up from their warehouse. I made the rookie mistake of taking their word for it and swapped motors. The new motor was making a terrible noise and not running right. After scratching me head for a few minutes BANG! from under the pedestal! I shut down the power and started to investigate, I found one of three caps under the pedestal suffered a catostrphic failure. I drove out to the warehouse where they had an old v4 on a pedestal in storage and took the caps from there. I replaced the caps and lo and behold the motor ran fine and quieter than a church mouse! I have never forgot that call, I was still pretty new and I remember feeling like such a genius for figuring it out
 

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Posted by Richard Fowler (Member # 893) on 03-25-2008, 06:15 PM:
 
Xetron or Big Sky may be able to get you the part....or the Prevost factory in Milan. I used to service many of these and that tension roller / air pot where service items.....with an occaisional sound lens focusing due to tampering.
 

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Posted by Gordon McLeod (Member # 33) on 03-25-2008, 09:37 PM:
 
I rip those caps out and run all my machines on an inverter either the Carlo Gavazzi or the Baldor
 

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Posted by Scott Norwood (Member # 30) on 03-25-2008, 10:11 PM:
 
Unless someone has a stash somewhere of NOS parts, you may have a hard time finding spares, unless you can get your hands on a parts machine.

These machines look nice, but pretty much suck (there are a couple of them in town). There are better options for 16mm.
 

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Posted by Paul Gordon (Member # 3320) on 03-26-2008, 06:04 AM:
 

quote: Scott Norwood

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Unless someone has a stash somewhere of NOS parts, you may have a hard time finding spares, unless you can get your hands on a parts machine.

These machines look nice, but pretty much suck (there are a couple of them in town). There are better options for 16mm.

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