Film-Tech Forum ARCHIVE: help with a fast projector

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Posted by Philip Wittlief (Member # 1724) on 09-21-2003, 05:20 PM:

We just recently installed a DP70 in our booth and it is running faster than it should. From my calculations is goes through a minute of film in about 55 seconds. Which is a little over 26fps. Any ideas on what can be done to fix this. Thanks

Posted by Greg Mueller (Member # 17) on 09-21-2003, 05:25 PM:

Sure it isn't set on the 30 fps setting?

Posted by Philip Wittlief (Member # 1724) on 09-21-2003, 05:38 PM:

Pretty sure it is not set on 30fps, and if it was then it would be off even more.

Posted by Darryl Spicer (Member # 711) on 09-21-2003, 05:54 PM:

How did you know it was a minute of film? Did you count the feet of film that went through. Here is the best way to check the speed. Loop 7 and a half feet of film together. THread the film and start projector motor. Take a stop watch and as soon as you hear the splice go through start the watch. Every click shoud be 5 seconds. If you count mor than 12 clicks in a minute then it is running to fast.

Posted by Philip Wittlief (Member # 1724) on 09-21-2003, 06:01 PM:

I did count the length of film I put through. I put 90 feet of clear leader in between some black leader, started the motor and started a stopwatch when the clear leader hit a reference point and the stopped when the tail black leader hit the same reference point. I got 54.64 seconds, of course there is error there due to my reaction time but I would estimate that to be less than a second for sure.

Posted by Steve Guttag (Member # 268) on 09-21-2003, 08:27 PM:

Generally DP70s are spot-on...Sync motors, I'm pretty sure.

For dual motor machines you have a gearbelt, on single motors you have a v-belt and a transmission....make sure the transmission is securely in the 24fps postion. Also make sure you have the original motors...I've seen some without the proper GE or Master motors that could affect speed.

Steve

Posted by Sam D. Chavez (Member # 1841) on 09-21-2003, 09:44 PM:

The belt should be checked to see if it's the right type. I've seen a non-metric automotive belt used in this application and if it's wider than the original it sits in the pulley higher and yields a higher speed.

Posted by Warren Smyth (Member # 1838) on 09-22-2003, 06:04 AM:

It's a real long shot, but your motor/drive isn't set for 50 cycles is it? I think this would give a speed of 28.8 fps if fed with 60 cycles.

[ 09-22-2003, 08:30 AM: Message edited by: Warren Smyth ]

Posted by John Spooner (Member # 1565) on 09-22-2003, 11:39 AM:

Warren. Tend to concur with your opinion. If the pulleys or drive are in fact set for 50 cps, then the system will run too fast on the US 60cps mains.
John Spooner. across the Tasman in South Oz.

Posted by Marc Jones (Member # 29) on 09-22-2003, 05:59 PM:

I'm not familiar with this projector but I would check the belts.
I had a micro V belt riding on the side of a flange which did effect the speed. So good luck

Posted by Mark Gulbrandsen (Member # 72) on 09-22-2003, 09:55 PM:

I would tend to agree with Sam on this one. Ya got to have the correct metric belt on the DP-70. Only other possibility is that someone took the dual projector drive pulley apart and re-assembled it with the pulleys in reverse positions.
Mark @ CLACO

Posted by Philip Wittlief (Member # 1724) on 10-24-2003, 10:32 PM:

What is the correct size belt for it. Today I switched belts with the other DP70 that runs correctly, and it didn't make any difference. Between the two machines I don't see anything that's different between them. Same motors, same belts, and belts in the same positions.

Posted by Gordon McLeod (Member # 33) on 10-25-2003, 08:44 AM:

In the base of the machines behind the lower magazine are some big square capacitors make sure none of the them are disconected they govern the speed to some degree

Posted by Mark Gulbrandsen (Member # 72) on 10-25-2003, 10:52 AM:

Actually if either of them is disconnected the motor simply will not run. One is the start capacitor and the other the run capacitor. I have seen these caps fail in older machines, and in machines that have been sitting idle for quite a while. I would change them out as there is a remote possibility that the run capacitor could be bad or possibly even the wrong cap all together. There were three styles of motors used on DP-70's over the years and all three used different value start and run caps. Look for the plate on your motor to see what type you have and then consult the service manual tech notes section of the DP-70 manual(actually the manual is three different sections) here on the F-T manuals page to be sure the caps are correct for your motor. If you replace them be aware that many of the "Older" caps are PCB filled. So take caution when you handle them. All new replacement caps are much smaller and non-PCB filled.

Mark @ CLACO

P.S. One other thing you can do is have a competant tech adapt a solid state drive motor system to your DP-70. This is what we will be doing on allfuture DP-70's that we sell.

Posted by Gordon McLeod (Member # 33) on 10-25-2003, 06:24 PM:

Some of them used multiple caps for the run value and under load it will effect the speed of the motor
been there and definetly done that

Posted by Philip Wittlief (Member # 1724) on 10-25-2003, 06:58 PM:

I think we got the problem fixed. Someone at some point in time in the life of the projector dissasembled the clutch and put it together with the pulleys backward. I haven't done an actual measurement yet, but rearranging these pulleys on the clutch definitely slowed it down, and it seems to be at the right speed. I will do an official time check when I have time. Thanks for the help.

Posted by Mark Gulbrandsen (Member # 72) on 10-25-2003, 08:18 PM:

Phil,
That is definately a possibility!! If someone took it apart to clean and lube it then they may not have paid attention to which one went where [Confused]

.
Mark @ CLACO