8mm Forum: Spare Speed Board GS1200?

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Posted by Alan Rik (Member # 73) on March 23, 2004, 03:36 PM:

This is for you Elmo Techs out there.
Where can I get a spare Elmo Speed board for the latest revision of the GS and can someone tell me how to install one?
Thanks!

Posted by Tony Milman (Member # 7) on March 23, 2004, 04:02 PM:

Alan

I think Pedro on this forum might be able to help

Tony

Posted by Kevin Faulkner (Member # 6) on March 24, 2004, 05:33 AM:

Why do you need one Alan? Do you have speed variations? Wittners in Germany are a good place to start as I do believe that they had some at one time.
www.wittners.de

Kev.

Posted by Alan Rik (Member # 73) on March 24, 2004, 08:16 AM:

Hey Kev,
I just purchased a GS1200 MINT (Well, thats what was said- will know later!) that is one of the first ones made. I remember my first GS was made from the same year. Sometimes when playing films it sounded a little warbly!
Then when I got both Xenon's which were later models they all had perfect sound in regards to pitch and speed. I guess I am anticipating the same wow and flutter and I wanted to change the speed board. Just jumping the gun...but was curious as to how hard it would be to do it myself. I am pretty handy with a soldering iron!
So.....provided I can find the board...how hard is it?

Posted by John Whittle (Member # 22) on March 24, 2004, 06:25 PM:

It might be easier to modify the original board. Do you have schematics for both boards? Know what changes were made? From your comments it would lead me to think that they made a change in the time constant of the speed variation. This might only require the change of a capacitor. Or it could a power transistor was changed for something more stable.

If the board is made of discrets rather than ICs, there might even be a service bulletin on the change.

John (who has no idea on how good Elmo was on service data to its dealers)

Posted by Pedro Santos (Member # 167) on March 25, 2004, 03:23 PM:

I had recently the same problems and I can tell you that only exchanging the speed bord helps! No power transistors on the speed board, but a special integrated circuit, that, of course, is out of stock at the dealers and out of production. But the complete board you can get at several dealers (Wittner, Soligor...) for about € 50. Simply plug it in and adjust the two speeds. If you don´t have any instruments to adjust the speed, record a sinus tone to a film (from a audio test CD), then change the board and adjust the pitch by ear, comparing with the CD playback.
At www.conrad.com you find a flicker meter, as used to test computer monitors. It shows the flicker frequency, simply by pointing it to the screen. And it wil shurly also show the flicker frequency of a projector. The device is very cheap (about € 10)
Pedro

Posted by Tony Milman (Member # 7) on March 26, 2004, 01:10 AM:

Alan,

I found the speed board last night and adjusted the speed of the 24fps which was running a little slow. The board is located in the bottom right of the machined and is mounted on posts on top of the main board. It has a small I.C in the middle and two variable resistors stand out of the front of the board.

The left hand one controls the 18fps circuit and the right the 24fps one. I nudged the right one using a non conducting screwdriver to the right to speed up the motor. It had to only be moved from the 12 noon position to about 1 o'clock to achieve the desired change. I actually used Pedro's crystal unit and judged it on the relative sound the motor made with and with out the unit. I will run a proper sound test later.

Happy to email a photo if you need one.

Tony

Posted by Alan Rik (Member # 73) on March 26, 2004, 06:46 AM:

Ok! That is great news. I am going to look at the GS and see what I can do. In the interim, Pedro, I have contacted Wittner but have not heard back from them. Do you have the contact number for one of the places that would have the speed board?
Thanks!

Posted by Antoine Orsero (Member # 41) on March 26, 2004, 10:30 AM:

Pedro,
I did not find at Conrad's the flicker meter. Please say to me in which column you found it.
As regards Wittner I suppose that it is a question of http: // www.wittner-kinotechnik.de/.
If that's right I do not see speed bord on sale.
Please help me.
Thank you very much
Antoine from France [Roll Eyes]

Posted by Kevin Faulkner (Member # 6) on March 28, 2004, 05:11 PM:

Alan, I have to say that our Tony is spot on with his info. Before you condem the board you should see if the bottom tensioner on the machine is moving up and down a lot. Its the black plastic item just before the second sprocket after the sound capstan.
The earlier machines with the old film path (loop out under lens) were prone to wow. The later film path layout was much better.
The later machines had different take up motors with a differnt torque spec which out a more even tension on the film. This also helped.

Kev.

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