8mm Forum: 8mm Elmo GS-1200

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Topic: 8mm Elmo GS-1200

Roderick Downes
Junior
Posts: 6
From: Chelmsford, England
Registered: Sep 2018

posted September 28, 2018 03:23 AM

Anyone had this problem? My GS-1200 was OK until the motor stopped with a burning smell. I checked the 2 resistors R328/329 were burnt so I replaced them.The diodes D6,7, & 8 are OK.Now motor runs flat out with no speed control.
Any ideas???

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Phil Murat
Jedi Master Film Handler

Posts: 671
From: Villeneuve St Georges, France
Registered: Dec 2015

posted September 28, 2018 03:56 AM

Hi Roderick,

I assume this is a good question for Leon Norris.

You can contact him here. He is ELMO expert for USA.

Is it this board ?

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Thomas Knappstein
Expert Film Handler

Posts: 124
From: Erwitte, Germany
Registered: Oct 2017

posted October 07, 2018 01:46 AM

Hi Roderick!
When the Motor runs flat please check The Voltage on the Transformer (AC) and after the black and green Rectifiers (DC) which gives the Motorpower. There must be about 35V DC on the 2200µF Elko. If this is OK check the Motor inside. It could be very dirty because of the Carbon Brushes. Clean it up and try it again. Look if the Diodes are not soldered out from the Heat they got when the Motor stops. If you have another GS test the Motor control Board in this one.

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Roderick Downes
Junior
Posts: 6
From: Chelmsford, England
Registered: Sep 2018

posted October 07, 2018 08:11 AM

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Roderick Downes
Junior
Posts: 6
From: Chelmsford, England
Registered: Sep 2018

posted October 07, 2018 08:16 AM

Thanks for your reply. I have 2 of the main motors & tried them both with the same full uncontrollable speed.
I have checked all the components on the small control board and they appear to be OK. I remember when putting the board back in, the motor didn`t run until I wiggled the board. Maybe the connections are not making properly. I have a mind to solder small wires from the board to the spigots to see what happens. Everything was OK until the burn up of the 2 resistors R328/329

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Thomas Knappstein
Expert Film Handler

Posts: 124
From: Erwitte, Germany
Registered: Oct 2017

posted October 08, 2018 08:40 AM

Before changing the little Control Board change the three Diodes on the Main Board. I think they could be damaged inside too. If there is a fault of the IC on the little Board, the Motor will runn with highest Speed. Have you checked the Relais Contakts on both Relais on the Main Board? They could be damaged too when the Motor shorts the Electronic. You must change Step by Step every Part of the Motor driving Section. Have you look in the GS 1200 Servise Manuel?
There is a Step by Step analytic for every Defet.

Sorry for my bad english.

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Leon Norris
Jedi Master Film Handler

Posts: 958
From: Elkins Park, PA, USA
Registered: Jun 2012

posted October 09, 2018 10:01 AM

The problem you are having with your GS is most likely coming from the governed circuit board check the IC on it if that is bad that will cause your speed problem and also check the ESS circuit board that also control the speed so get back to me and let me know how you made out with your machine because I have all the parts to fix it

Leon Norris

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Roderick Downes
Junior
Posts: 6
From: Chelmsford, England
Registered: Sep 2018

posted October 12, 2018 03:01 AM

Thanks Thomas & Leon for your replies.
I will check all that you`ve suggested when I get a chance.

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Thomas Knappstein
Expert Film Handler

Posts: 124
From: Erwitte, Germany
Registered: Oct 2017

posted October 12, 2018 11:07 AM

When the Main Motor run at very high speed the 2SA720 Transistor on the Motor Control Board could be damaged.

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