quote:

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...but over a length that short your reaction times on the stopwatch button could easily make it inaccurate over a second or two.

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Hopefully someone skilled in using a stopwatch isn't in error by that much!
 

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Posted by Michael Schaffer (Member # 1204) on 02-10-2003, 10:26 AM:
 
Another - again, somewhat imprecise - method which will reveal more drastic problems is to run a 1 kHz loop and then use a tuning device to measure the pitch of the output.
For instance, if the projector is running at 22 fps, the frequency will be around 915 Hz.
 

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Posted by John Hawkinson (Member # 1135) on 02-10-2003, 01:16 PM:
 
I think John's methods are the only really good ones. Stopwatch measurement should not be off by more than 250ms or so. Anything else is criminal.

Leo suggests using a "known good projetor." Unfortunately there's no such thing. You would be surprised how many projectors are off by just a little bit. Unless you measure it, don't presume a baseline, because chances are you'll be wrong.

Michael suggests using 1 KHz tone. Unfortunately, 1 KHz tone is generally not at 1 KHz. It's designed to be a gain reference around 1 KHz, but my experience is that it may be significantly off from 1 KHz (e.g., around 50 Hz off).

--jhawk
 

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Posted by Michael Schaffer (Member # 1204) on 02-10-2003, 01:33 PM:
 
True, but you can check that. If you have a FP30E within reach, you can run the test loop and check its frequency. The FP30E are usually very reliable. Generally, I found the 30 series Kinoton machines very stable. We have often used them in multiple interlock situations and the - I don`t know the proper English term - "gallows" which you have between the machines never moved up or down.
edit - I just thought of another method: Prepare a known length of film. Add some material at the beginning to allow for the speedup time of the projector. Make a hole on the soundtrack of the film, and another a known length of film later. Record the output on your notebook. Then you can see exactly how big the time span between the two pops is.
 

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Posted by Paul G. Thompson (Member # 655) on 02-10-2003, 02:01 PM:
 
I don't think a stopwatch would be that inaccurate. Allowing for human lag time while punching the stem, the lag time will be the same at the start as it would be the finish unless you had an "itch" to tend to...

Seriously, reaction time would be very consistant although it would probably vary from person to person. However, the end result would still be consistant. If you analyzed that, the old carbon arc operators were very consistant in hitting the motor and changeover cues almost right down to the split second.
 

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Posted by John Pytlak (Member # 331) on 02-10-2003, 02:13 PM:
 
Once upon a time, people and stopwatches were considered accurate enough to time short athletic events, even for world records. Those times are recorded as "official" in the record books. The error in timing a 1-minute run of film with a stopwatch is probably negligible. You could always time a longer run, or take the average of several runs.
 

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Posted by Daryl C. W. O'Shea (Member # 1303) on 02-10-2003, 02:24 PM:
 
If you believe that only a computer can be accurate, you could always hook up a DTS-6AD to the machine and just check the film speed registered by the DTS reader.

I however believe that you should easily be able to be within a quarter of a second. Unless of course you're doing a physics lab and need a source of error.
 

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Posted by Rick Long (Member # 213) on 02-10-2003, 04:06 PM:
 
Back during the Sensurround installations (when the speed of the projector (and thus, frequencies derived from the film to trigger the system) had to be reasonably accurate) we used John's method of the 7 1/2 foot loop.

As John points out, it should pass a given point in the projector every 5 seconds. Leave it run for a couple of minutes or so, and you should hear the splice at the same point on your watch. (5, 10 15, or
2, 7, 12, ect.).
 

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Posted by Michael Schaffer (Member # 1204) on 02-10-2003, 05:42 PM:
 

quote:

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If you believe that only a computer can be accurate, you could always hook up a DTS-6AD to the machine and just check the film speed registered by the DTS reader.

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quote:

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BTW, a quarter of a second is six frames. That does not strike me as particularly precise.

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quote:

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Because the DTS players use a phase lock loop (PLL) to lock the timecode to the projector speed (motor)

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Do you have to thread a loop of film through the dts reader and sprockets to move it or is the phase picked up at the motor itself?
Florian, which part number in the Conrad catalogue is it?
 

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Posted by Florian Pausch (Member # 708) on 02-11-2003, 09:40 AM:
 
Michael,
it is:
ELV-electronics
"Screen-check SC-200", Part Nr. 68-314-86, € 9,95
 

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Posted by Karen Hultgren (Member # 395) on 02-11-2003, 11:49 AM:
 
Michael,

You do not need to thread film. We lock to the projector motor.

Karen at DTS
khultgren@dtsonline.com
 

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Posted by Jim Spohn (Member # 1547) on 02-11-2003, 01:35 PM:
 
The last time that a speed problem came up several people posted some very clever ways to check the speed. Steve Kraus had the one I thought to be the most clever, using a solar cell in front of the lens with the cell hooked to a meter in the frequency counter mode to count the shutter passes. The most simple however appears to be the 5 second loop. The loop can be run thru an infinite number of times for timing purposes. The more times the loop cycles, the greater the resolution. It's simple quick and dirty and anyone can do it with no special tools or equipment and end up with amaising acuracy. My hat is off to all you clever guys!!...Jim
 

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Posted by John Hawkinson (Member # 1135) on 02-11-2003, 04:27 PM:
 
Err, Karen, .

We're talking about a regular DTS-6D with the standard timecode reader?

--jhawk
 

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Posted by Michael Schaffer (Member # 1204) on 02-11-2003, 04:57 PM:
 
That is what confused me too. But Karen is referring to the dts-6AD. Still, I don`t understand why this is necessary when the dts-6D works effortlessly just from the timecode reader?
 

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Posted by Karen Hultgren (Member # 395) on 02-11-2003, 05:36 PM:
 
I am talking about checking projector speed with the DTS reader and the DTS-6/-6D/-6AD players. All of them have the PLL circuit that act in the same way. And, I made a mistake, you do need to run film. The reader needs to be sending speed info the the player. Use the 1kHz tone and monitor it at the output of the player.

Karen at DTS
khultgren@dtsonline.com
 

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Posted by Steve Kraus (Member # 476) on 02-11-2003, 06:11 PM:
 
Paraphrasing myself from just a month ago:

If you want to check the speed you can use a solar cell, perhaps an old mono one out of your junk box, otherwise get a cheap one at Radio Shack (or UK equivalent), connect it to your DVM set for frequency measurement, and hold it in the light beam. With a 2X shutter (double blade or single blade, double speed) you will be looking for a deviation from 48 Hz. With a three-blade 3 blade look for 72 Hz.
 

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Posted by Frank Angel (Member # 248) on 02-11-2003, 06:15 PM:
 
So we figured out some inventive ways to determine if the projector is going slower or faster than 24fps. OK, you clever lads....NOW WHAT?! Finding out if it's slow or fast is a piece of cake -- doing something about it is a lot more vexing. It's not as if these things have a speed control on them, eh? Induction motors are not about to be coaxed into going faster or slower than what they want to go at, and the synchronous babies, if they are not going at the right speed, then you really have a complicated problem going on, or maybe even a few of them.

Sometimes it may be better not to know

Frank
 

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Posted by Scott Norwood (Member # 30) on 02-11-2003, 06:41 PM:
 
Stupid semi-relevant question: what's the difference between the FP20 and the current-model FP30? Is the FP20 mechanical or electronic (the FP30 comes in both versions)? Are there other differences? They look very similar in photographs, but I've never seen an FP20 in person.
 

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Posted by Rick Long (Member # 213) on 02-11-2003, 11:55 PM:
 
Getting back to the "5 second loop" how would one calculate how far off speed the projector was?

If for example when the measurement started, the splice could be heard at the 3,8,13,18 ect. points on the second hand, yet five minutes later they were falling at the 2, 7, 12, 17 ect. points, what lower speed would this represent?

Calling professor Criswell.....
 

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Posted by Daryl C. W. O'Shea (Member # 1303) on 02-12-2003, 01:40 AM:
 


So in your example:

24fps x 300s / (300s - 3s + 2s) = 24.08fps actual speed
 

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Posted by Gordon McLeod (Member # 33) on 02-12-2003, 11:01 AM:
 
Well you could misalign the sound head to scan the perfs and that should be 4x24 or 96 HZ on a frequency counter
 

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Posted by Dave Macaulay (Member # 813) on 02-12-2003, 03:24 PM:
 
Any known size film loop (a multiple of 24 frames - assuming you run 24fps - is a wise plan) and a stopwatch can be as accurate as you like with a stopwatch. If you time 12 passes of a 120 frame 5-second loop with a stopwatch you will be pretty accurate against the expected 1 minute...
 

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Posted by Rick Long (Member # 213) on 02-12-2003, 09:49 PM:
 
A stop-watch introduces the factor of human error in pressing it's stop button. (Did you hiccup before you pressed it?).

Besides I have enough test equipment to carry up to the booth as it is.

Further, not many projectionists have access to a frequency counter.
 

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Posted by Mark Maxwell (Member # 1355) on 02-13-2003, 01:17 AM:
 
I have an FP20 manual that I can mail you. The problem is that I won't be back at my theater until Saturday, and every other fourth page is in english, so I'll have to undo the binders and put the english pages together to photocopy and mail it to you. Just don't pay attention to the index because it will mess you up if I just send you the pages that are in English.
 

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Posted by Mark Maxwell (Member # 1355) on 02-13-2003, 01:37 AM:
 
You are all going to think I'm stupid for this. There aren't a whole lot of FP20's out there. And probably few that have DTS. I'm lucky to have three of thase that have it. The motor runs everything on theese machines. If the motor runs slow, everything else does. Get a manual for one of the things. Get a multimeter and see if the motor is getting the power it should.
If it is, thread up a reel of old trailors and thread it through the projector onto a platter. Theese are old reel to reel projectors, so they should feed the film in at the same speed. Use a hand held rpm tester against the reel on the mut(there is such a thing) and see if the reel is spinning slower than it should. And that's a regular reel, not a big house reel. If it's not running to speed, check the motor, or the power supply.
 

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Posted by Larry Shaw (Member # 388) on 02-13-2003, 08:40 PM:
 
Scott,

The FP-20 is a belt drive machine, V-belt for async and toothed belt for sync. It has been out of production for many years. It has a smaller chassis than the 30 and a convex rear door. The 20's replacement is the FP-30. Early production was belt drive and no suffix was used. Later the model became FP-30D, meaning direct drive, which also used a inverter to smoothly run the motor. Later still the FP-30E was introduced, with the servo drive intermittent to reduce jump to nearly 0.
 

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Posted by Bill Gabel (Member # 1105) on 02-13-2003, 08:49 PM:
 
Hi Larry

I have a pair of Magna-Tech PR-135 Studio Projectors. They
are a upgrade of the Kinoton FP-20 machine. They have been
in this location for over 18 years. They handle film great.

 

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Posted by Rick Long (Member # 213) on 02-13-2003, 10:36 PM:
 
Another clue might be motor temperature. Motors running below the speed for which they are intended, tend to run hot.
 

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Posted by Michael Schaffer (Member # 1204) on 02-14-2003, 01:18 AM:
 
Larry, doesn`t the "D" stand for digital meaning the FP-30 which comes complete with the Dolby reader?
 

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Posted by Steve Guttag (Member # 268) on 02-14-2003, 09:24 AM:
 
(Speaking for Larry at the moment)...NO the "D" does not stand for digital. The FP-20 and 30 series were both offered in "D" versions. The "D" series have all offered the ability for multiple speeds (due to the 3-phase motor controller). The "D" series was the last model of the FP-20 and both FP-20D and FP-30D models were offered concurrently.

The "D" did not guarantee that it would be Direct Drive though...an FP-18D (16mm) still used a belt between the motor and shutter.

Personally, I preferred the FP-20 line of projectors over the FP-30...they were sleeker and more solid. The FP-30 frame is more flexible in the sense of different configurations and is, no doubt, less expensive to manufacture.

Steve
 

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Posted by Michael Schaffer (Member # 1204) on 02-14-2003, 10:06 AM:
 
Indeed, the "D" does not stand for the integrated digital reader. I do not know about the FP-18D, but it seems that "D" does stand for "Direktantrieb"=Direct Drive. Well, Larry has the most direct access (LarryD=Direct Access) to the information.
 

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Posted by Rick Long (Member # 213) on 02-15-2003, 01:25 AM:
 
Steve's picture must be running in an FP-20. So far, no new scratches.
 

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Posted by Pete Naples (Member # 761) on 02-15-2003, 04:34 AM:
 
To check projector speed I use a hand held tachometer. Drive it off any constant speed sprocket shaft and read the display. It's pretty easy maths to calculate what 24fps = in rpm for different machines.
 

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Posted by Larry Shaw (Member # 388) on 02-15-2003, 04:10 PM:
 
Michael, Steve is correct in his speaking for me on this. But don't feel bad, lots of people assume that is what the "D" means. The vast majority of 20's are suffix-free, but there are a few odd ones to be found (EG: "-A" for a particularly basic version made for a while). If you go to http://www.kinotonamerica.com/technical.htm , just below the tech notes there is a list of model codes I wrote a couple of years ago. As you can see, there is a downside to having such a broad (and always expanding) range of projection equipment. And yes, I know I need to update it. Any suggestions are always welcome.

I can't really explain the 18D. I think it was done so all the mechanical drive (as opposed to servo intermittent) machines ended in "D". The D was also added to the DP-75 around that time if memory serves. But I'm sure an exception can be found.

And Steve is correct that the 20's frame was more rigid. But it was smaller inside (harder for servicing), was very tough to drill or punch, not easy to add options or upgrades to, and very expensive to build.

Bill, thanks for your comments on the PR-135. As you know MTE made a lot of mods in those. Of course later they made "their own" projectors, but we supplied the gate assy's, soundheads, lens holder assy's and a bunch of other stuff.

Regarding the original post, If I had a FP-20 that ran slow, I'd first check belt slippage (assuming V-belt drive), then see if the aluminum motor pully was worn.
 

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Posted by Michael Schaffer (Member # 1204) on 02-15-2003, 04:24 PM:
 
Oddly, I remember that it was a technician from Kinoton Germany who told me that it was for digital.
But you are right of course.
Another question. Why don`t you let film-tech publish the Kinoton manuals on this website?
BTW I find Kinoton projectors better than most other types I have seen. But why do you reside in "Goodenough Street"? Shouldn`t you be more self-confident...
 

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Posted by Larry Shaw (Member # 388) on 02-15-2003, 05:34 PM:
 
Michael,

The decision not to put the manuals on-line comes from Kinoton in Germering. Simply, they own the copyright, after several requests they have decided "NO", so no it is. Sorry.

The street name is abbreviated. The full name is: "Foryourtheatreourcompetitors'projectorsarenotgoodenough Street"
 

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