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Old 07-17-2021, 07:20 AM   #30
biphase
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Join Date: Jan 2009
Location: Ocala, FL
Posts: 384
Default Re: Melex 252 Curtis controller 1204 bad?

When you reassembled your controller, were you careful to restore the internal insulator between the aluminum heat sink and the box. The heat sink is connected to the M- blade and it is supposed to be isolated from the golf car chassis by an insulator. If somehow your chassis is connected to B-, you could be effectively shorting M- to B- if that insulator is missing or improperly installed. The six screws securing the heat sink to the box are also connected to M- so they must be insulated from the box and the chassis mounting surface. Shorting M- to B- effectively bypasses the controller and will cause the cart to run uncontrollably at max speed. Remove the controller and test to see if there is a short between the M- blade and the box.

You could try running the cart temporarily with the controller box isolated from the mounting surface to see if the cart runs properly. You should be able to stop a runaway cart by putting it in neutral. Of course, you should always test the cart with the rear wheels off the ground.
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