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This topic comprises 2 pages: 1 2
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Author
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Topic: Kinoton MP75 E Intermittent
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Randy Stankey
Film God
Posts: 6539
From: Erie, Pennsylvania
Registered: Jun 99
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posted 04-25-2012 03:42 PM
We have a Kinoton MP 75 E (running 8/70) which is tearing up film. Film tears up below the intermittent while running.
The intermittent makes a sqealing sound, similar to what you would hear if a bearing is going bad. It only makes this sound when the intermittent tries to take a step. Either if the motor is running or if you turn the machine over by hand.
If the machine is running the sqealing sound is constant. If the machine is turned over by hand, the sound is intermittent, only as the sprocket tries to turn.
If you put your finger (carefully) on the intermittent sprocket as it turns, you can feel it vibrate. It occasionally stutters, too.
If you put your hand on the intermittent drive motor, inside the back of the projector, you can feel a vibration there, as well.
This problem has occurred within the last 24 hours. I operated all day yesterday with no problems. My coworker operated the first few shows today with no problems. It has only occurred during the last show.
The theater is down until this is solved. The tech who services this theater is not available.
Our assumption: The intermittent drive motor has gone bad and needs to be replaced.
What do you think?
Assuming this is true, what is the difficulty level of replacing this unit ourselves? Both my coworker and I have experience to make repairs on other projectors but have never done something like this ourselves.
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Randy Stankey
Film God
Posts: 6539
From: Erie, Pennsylvania
Registered: Jun 99
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posted 04-26-2012 05:14 PM
Got the servo motor changed. Projector is operational enough to present to the school group that's booked for tomorrow but it still needs work.
I think the reason for the failure was because the outboard bearing went bad. We couldn't get the bearing support off the shaft. It was frozen in place. The bearing still turned but it was all "gravely."
The servo motor, the bearing and the intermittent sprocket have all been replaced.
According to the manual, the intermittent sprocket needs to be 42.5 mm from the "main plate" but we can't figure out where the datum line for that measurement is.
We tried from the metal bulkhead of the projector. That wasn't right. We tried from the intermittent support casting. That didn't work either. In the end, we put a piece of film in the gate and aligned the intermittent by eye. That was enough to get it running but it's not perfect.
We need to know where the datum line is to get it right.
The intermittent is steady enough but it's not perfect. At the screen, there is between a quarter and a half in inch of vertical jitter. That's "okay." Just okay. It still needs to be improved. We need to get that sprocket aligned with the gate to cure the weave problem too.
So, how, exactly is this intermittent calibrated?
I have a scope. Do you connect it to the three pins on the bottom left corner of the servo drive control amplifer? Which pins are which?
We have a computer that can connect to the serial port of the drive control. I'm sure I can learn the software well enough to do the job. How can I get it?
The reason I'm asking is because the tech who services this theater isn't gong to be able to come to our location for several days. They are in Vegas.
Judging by the way they talk, they aren't fully versed in how to calibrate this machine, anyway. Or, at least if they are, they aren't talking very much.
If this is going to get done right, we're going to have to do it using our own resources.
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Randy Stankey
Film God
Posts: 6539
From: Erie, Pennsylvania
Registered: Jun 99
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posted 04-26-2012 09:11 PM
No, but I'll suggest it.
After only having worked there for three weeks, I'm in a tough position. I want things to work right and I want to show that I can make things work right or, at least, find people who can help us get it right.
Today's exercise has helped further that but I think it's still too early to be telling people that they should do things.
The contractor who installed and services the equipment is from Florida. We're in Pennsylvania. Worse, everybody is in Vegas, right now. Monday is probably the earliest time when people will be available to really help out.
I spent some time, today, to study how things work and I think I'm starting to understand. A lot of things seem to work very similar to the way a Christie projector works, only better engineered.
I get the general idea of how the servo drive works. (I damn well better! I just tore one out and replaced it! ) Given that I have only worked with it for a short time, I think I understand what needs to be calibrated: The step angle and the timing has to stay in sync with the speed of the film and the rotation of the shutter. The principle is the same as a gear driven projector but the servo controller looks at the blanking signal from the shutter to know when to tell the motor to turn. Then it reads the signal from the position sensor on the servo motor to know when it has turned far enough. Instead of gears and cams, it's electronic signals and motors.
The procedures for getting things to come together, I think I can work out. What I really need are the specs, timings and measurements.
Unless I have a 100% working projector in front of me to study, those things are pretty hard to work out without help.
I'll mention Boston Light and Sound, tomorrow, when I go back to work.
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Randy Stankey
Film God
Posts: 6539
From: Erie, Pennsylvania
Registered: Jun 99
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posted 04-27-2012 12:23 AM
I have a set of manuals for them but they aren't entirely helpful.
First off, they are translated from German and the translation is a bit klunky. Second, the information isn't all there or makes assumptions that you know things and glosses over certain points.
To remove the intermittent sprocket, the manual instructs you to remove the clamping collar from the outboard end but, in reality, there is also another one on the inboard end but the manual makes no mention.
To replace the intermittent sprocket, it says that it should be 42.5 mm. from the "main plate." I assume that means the bulkhead is the datum but, when I tried that, it came our wrong.
Similarly, the manual says, to calibrate the servo motor, you hook your oscilloscope to the control module. It shows where the test points are but it does not explain which test points are which. Okay, so one has to be ground and the other two have to be signal but which is which? It does not say.
Description of the software is just as vague, explaining about phase angle and timing but glossing over the fine points.
In terms of how the projector works, most anybody who knows how to work on more traditional projectors can figure it out. It's just these little details that the average person wouldn't know which will trip you up.
I'll figure it out because the gauntlet has been thrown down.
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Randy Stankey
Film God
Posts: 6539
From: Erie, Pennsylvania
Registered: Jun 99
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posted 04-27-2012 10:05 AM
The flow sensor works. I checked it when I changed out the movement.
It is a little, plastic cylinder spliced in-line with the water supply hose. You can look at it and see the vanes spinning when the fluid is flowing. The vanes do spin.
When the system was first installed, they did have a problem with the cooler. If the level gets too low, the pump churns the fluid, causing it to foam and reduce flow.
One of the first things I was told in training was to make sure that there is enough water in the tank. We check it every morning and we add distilled water about once per week.
I'm pretty certain that the main failure was because the outboard bearing on the intermittent shaft failed. It still turned but it felt like it was full of gravel. I'm sure this was a slow failure that put too much load on the servo motor, causing it to give up the ghost.
After replacing the servo motor, the projector runs much more quietly. In the time I worked there, the intermittent had always made a ticking sound as it turned over. After the replacement, the projector is virtually silent if there is no film in it. Turning over by hand, there is no sound. When running, the only sound is the motor. It's a bit weird to hear a machine run so quietly. I have never heard a traditional mechanical projector run so quietly.
The main issues we have, now are getting the sprocket and gate aligned correctly. I need to find the datum point for that measurement. You can't use the old steel ruler trick because the the feed and holdback sprockets aren't the same dimension as the intermittent.
I'm probably going to change the skids the next time I have the chance. (With proper study beforehand.)
The timing of the intermittent is tolerable. I think most of the steadiness problems are because the trap and sprocket aren't aligned properly. These are my main concerns.
I will keep the intermittent calibration on the back burner until the other problems are solved because it's probably pretty easy to royally fuck the projector if you get it wrong.
Comparatively speaking, trap and sprocket alignment are fairly academic.
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