8mm Forum: 8mm Elmo GS-1200

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Posted by Roderick Downes (Member # 6635) on 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???

Posted by Phil Murat (Member # 5148) on 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 ?

Posted by Thomas Knappstein (Member # 6134) on 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.

Posted by Roderick Downes (Member # 6635) on October 07, 2018, 08:11 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 boiard back in the motor didn

Posted by Roderick Downes (Member # 6635) on 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

Posted by Thomas Knappstein (Member # 6134) on 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.

Posted by Leon Norris (Member # 3151) on 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

Posted by Roderick Downes (Member # 6635) on 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.

Posted by Thomas Knappstein (Member # 6134) on 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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