8mm Forum: Elmo ST-600M Plays Fast

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Posted by Timothy Price (Member # 1832) on March 23, 2014, 03:59 PM:

Howdy All-

My Elmo ST-600M plays fast at 24FPS. Can anyone tell me how to fine tune the speed.

Thanks!

Tim

Posted by Mark Todd (Member # 96) on March 23, 2014, 06:57 PM:

Hi Tim thee are 2 little adjustable potemeters in the back, with a small flat screw driver slot in but I can`t remember which does the 24fps.

Its usually when you go from the origional v belt to a round section one, or they can just seem to alter a little some times.

I`ve got the info on which one in an email somewhere so I will try to dig it out, but someone else will know.

Its an easy sort.

Best Mark.

Posted by Steve Klare (Member # 12) on March 23, 2014, 07:44 PM:

The trick to adjusting these is the transport has quite a bit of inertia, maybe due to the flywheel, so it is maddening to adjust:

You twist the pot until the pitch of the sound is pefect, you lean back in satisfaction, but then notice that the speed has continued to change. It was too slow before, now it's too fast, or vice versa. So now you apply the driver again and wrench it the other way, and overshoot it again!

Small changes, let it settle out, listen, make further small changes, more settling, more listening.

-otherwise you can wind up chasing the frame rate all over the map!

Sorry. I don't know where the pots are on an ST-600. I have an ST-800

Posted by John Hermes (Member # 1367) on March 23, 2014, 10:22 PM:

Looking from the back of the projector, the 24 fps pot is on the right. One way to adjust the speed is to put a marker line on one of the sprockets. There are 18 teeth on the sprocket. It will turn one revolution for every .75 seconds at a correct 24 fps. Use a stopwatch and start the watch as the line hits the top. Count forty revolutions and stop the watch. If it is right on speed, the watch will have stopped right at thirty seconds. If the projector is running fast, it will be less than thirty seconds, and vice-versa. Make adjustments to the pot until it is as close to thirty seconds as possible. You can also do the 18 fps pot this way, except you will count thirty revolutions.

Posted by Steve Klare (Member # 12) on March 23, 2014, 10:35 PM:

I want to build a device that captures the flashes of light coming out of the lens and changes their frequency into a voltage that I can read on a voltmeter, but then again I have about ten projects in front of it, including stuff like "paint the front door" and "cut down that really ugly tree in the back yard before it falls on the shed".

(Best intentions...)

Posted by Timothy Price (Member # 1832) on March 24, 2014, 09:29 AM:

You guys are awesome! Thanks soooo much!

Steve- Don't let the tree hit the shed or the s**t will hit the fan! [Smile]

Posted by Steve Klare (Member # 12) on March 24, 2014, 09:55 AM:

Well, I may work a compromise:

I'll cut it down and while I'm at it it may fall on the shed anyway!

Posted by Timothy Price (Member # 1832) on March 30, 2014, 05:26 PM:

OK- I've opened the back of the ST-600 and cannot seem to find anything where I would adjust the speed! HELP!!!!

Posted by John Hermes (Member # 1367) on March 31, 2014, 01:15 AM:

Timothy, on all the ST-600 projectors I've seen (including the three I have) there is a 1 1/2" x 3" board about right in the center (just to the left of the big transformer), with two small trimpots facing you on the front edge of it. The pots are very small, about 1/4" diameter. The one on the left is for 18fps and the one on the right is for 24fps. I've seen some ST-180 models with the board and pots toward the very back of the projector.

Posted by Timothy Price (Member # 1832) on March 31, 2014, 07:44 AM:

Got it John! That helps a lot! Looking at them right now!

They each have a small rectangular shaped hole in them. I'm guessing you insert a small screwdriver and turn these to fine tune the speed?

Really- Thanks for taking the time to take and post a pic. I really, really appreciate it. [Smile]

Posted by John Hermes (Member # 1367) on March 31, 2014, 11:18 AM:

I'm glad I could help, Timothy. They make a insulated screwdriver-like tool specifically for adjusting pots, bladed on one end, open on the other for a different type pot. You can use a small regular screwdriver, but make sure it has a plastic handle or your body resistance will interfere the adjustment. It is an easy adjustment. Good luck.

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