8mm Forum: Elmo GS 1200 Motor won't run???

This is topic Elmo GS 1200 Motor won't run??? in forum 8mm Forum at 8mm Forum.

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Posted by David Evans (Member # 482) on August 01, 2006, 11:18 PM:

Hi

Recently acquired a GS-1200 - lovely machine, just has an odd fault:

Set it up, plugged it in, loaded film, good picture, good sound. Fine, except occasionally the main shutter motor would stop dead and the film would melt..... a few seconds later it would start running again if one hadn't hit the stop button by then.

Cleaned & lubricated bearings. No difference. Inspected main printed circuit board and found a dry joint on a relay connection. Corrected it. Motor ran fine for about an hour, then repeated the instantaneous stopping.

Then read the manual! Found the ESS switch was in ESS position, not Normal position. The manual says it should not have run at all in the ESS position unless external sync pulse signals are present. Switched the ESS switch to normal. The motor has since refused to run at all in any position of any switches.

Do any of you technical experts know this fault?

I checked the voltage across the motor. Both terminals are at approx 26 volts +ve with respect to chassis, and therefore there is no potential across the motor terminals, so naturally it doesn't run.

Do I need a replacement motor control board, I wonder? I see it is full of integrated circuits.

Does anyone have a service manual (including complete circuit) I could buy?

Thanks for any advice you can give.

Regards from sunny Canada!

David Evans

Posted by Joerg Niggemann (Member # 611) on August 01, 2006, 11:41 PM:

David, the GS1200 Service Manual is available as pdf file in the "manuals" section of this forum. Did you check the ESS switch contacts?

Joerg

Posted by Kevin Faulkner (Member # 6) on August 02, 2006, 12:54 AM:

Yes thats the most likely. Try moving the ESS switch back and forth a dozen or so times. The contacts have probably become tarnished with age and lack of use.

Kev.

Posted by John Clancy (Member # 49) on August 02, 2006, 02:50 AM:

If all else fails you could always get a Pedro crystal sync' box and just have the GS running in pulse (ESS) mode.

Posted by David Evans (Member # 482) on August 02, 2006, 10:51 AM:

Thanks! I'll try Kev's suggestion first! Will let you know how it goes. Any idea where I could get either a motor control board or the sync unit?

Thanks for the info, Joerg. It's not immediately obvious (to me) how you get to the Manuals section. I know I'm an idiot and it must be obvious!!! Will persevere...

Regards

David

Posted by Joerg Niggemann (Member # 611) on August 03, 2006, 07:41 AM:

David, maybe it's an issue with your browser, but you should see the manuals section in the main window. Unfortunately, the file is a little too big for email transfer...

Joerg

Posted by Jan Bister (Member # 332) on August 03, 2006, 09:26 AM:

Joerg, some of us have gone with the times and are browsing the web using Firefox and such [Big Grin]

Which means tabbed browsing - which, in my case, means I open links in new tabs, which means the menu on the left-hand side doesn't show up in the new tabs (as it's a separate frame). To get it back, all one needs to do is manually re-visit http://8mmforum.film-tech.com/ - or better yet, just go to the main page http://www.film-tech.com/ and go to the manuals from there. [Smile]

Posted by Joerg Niggemann (Member # 611) on August 03, 2006, 02:35 PM:

"You shall have no other browsers before MSIE!!"

Posted by Jan Bister (Member # 332) on August 03, 2006, 03:11 PM:

Hey, I thought the browser wars ended with the advent of Mozilla. [Big Grin]

Posted by David Evans (Member # 482) on August 04, 2006, 11:12 AM:

Hi All

Joerg, thanks for the excellent screen image, but no, I don't get the buttons at the left. Probably comes about through using AOL......

However, I did find a ref to the Film-Tech site elsewhere in this Forum & downloaded the manual from there. So thanks to all involved!

Have tried operating the ESS switch many times - no effect at all and still no motor running. Will consult the manual now I have it, but have been involved in a family wedding for the last couple of days and haven't had a moment.

Thanks again!

Regards

David Evans

Posted by John Clancy (Member # 49) on August 05, 2006, 07:46 AM:

Has anyone saved Pedro's crystal sync' web page in their favourites to save me searching for it?

Kevin, how about those overheating diodes? Are they a possibility for the problem detailed here?

Posted by Jean-Marc Toussaint (Member # 270) on August 05, 2006, 07:59 AM:

There you go: Pedro's products

[Big Grin]

Posted by Kevin Faulkner (Member # 6) on August 06, 2006, 03:44 PM:

John, Yes that a very high possibility. There are 3 diodes inseries with the main motor which go to earth. They are marked on the diagram as D306, 307 & 308. The get quite hot and then can cause dry joints round their connections. When these go dry jointed the motor can become intermittent and eventually not run at all. They are situated on the centre of the main circuit board. With the back removed and the machine upside down you will notice bad scorch marks on the underside of the circuit board if this is the probelm. Normally removing the old solder and then resoldering a fresh will cure that problem unless it has caused damamge to the board in which case you would have to make good any damage first.

I have not to date found that these diodes have failed but where I have had this problem I have replaced them with new higer wattage types.

There is nothing special about the diodes. They are Standard rectifier diodes and anything of about 1 amp at 200V would be ok.
I tend to replace them with 5amp 200V types.

Part of Control Circuit Diagram.

Showing underside of main control circuit board.

Its also possible for the small motor control board to give rise to similar problems. You can get new boards from: FFR-Film Check in the Elmo menu. Item No.4768.

Kev.

[ August 08, 2006, 07:19 AM: Message edited by: Kevin Faulkner ]

Posted by David Evans (Member # 482) on August 15, 2006, 11:10 AM:

Hi All

Kevin, you are quite right, though I arrived at the same conclusion independently. Measurement showed that D308 appeared to be open circuit. I replaced it, together with R329 and R326, which had burned out. The motor ran for a few minutes, then stopped again. Measurement showed all three diodes to be OK. However, the connection on the board between D307 and D308 had gone open circuit (or intermittantly so, if you flexed the board). I paralleled the track with a separate wire, replaced R326 and R329 again and normal service appears to have been resumed. The original diode measures OK out of circuit, so I think the problem was the track all along. I hate PCBs with highish currents in them!

Thanks for your interest and advice.

Regards

David

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