Yamaha G8 Electrical issue solved (speed controller disassembled)

[george7806]

Let me say first that by looking up the serial number, it looks like my cart is a 1995 G14 Not a G8.So after numerous hours of troubleshooting different components, I've got the idea to bypass part of the speed controller. After running a wire from the main (-) of the battery bank to the S2 terminal of the motor had bypassed part of the speed controller, and surprisingly after turning the key on and stepping on the accelerator pedal the carts wheel were running (was jacked up). So it was time to remove the speed controller.Whoever made the OEM speed controllers didn't want anyone to disassemble it.The box is hollow inside, but has a thick foam glued both ends which looks impossible to remove without slicing the box open. So it was time to break out the band saw, and slice one side and the top open. Here is what I found.



Luckily it wasn't hard to locate the bad components by looking at the board, but still made measurements to make sure what works. Apparently the 8 transistors on the bottom can't handle heat so well, since all of the were split in half.



And the board removed. Also I had 2 resistor burned out.



By the way these transistors are "IRFZ48" which I couldn't get locally, but has found an equivalent. After de-soldering and replacing the 2 burned out resistors, I've hooked them up without installing it and it worked. So couple more brackets made out of aluminum and it was back together.I little paint and silicone to make it wheaterproof and I just saved myself a couple hundred $$$. I hope this will help to some of you with similar issues.

[smallblock450sl]

Nice job Great pictures and info. Glad you got it running again, and with your own 2 hands and a great mind.

[dwitt]

yep...thats what it takes...you gotta piddle with it yourself to get things fixed.
i pulled mine apart but could find nothing broken or cracked....(the search continues)
its good to have the know-how to replace resistors and things as well...

[george7806]

Originally Posted by smallblock450sl

Nice job Great pictures and info. Glad you got it running again, and with your own 2 hands and a great mind.

Thanks, I was relieved to finally see it running...after buying new batteries and charger, I was not about to put more money into the cart.And it's also a great feeling when you get something fixed:-)

Originally Posted by dwitt

yep...thats what it takes...you gotta piddle with it yourself to get things fixed.
i pulled mine apart but could find nothing broken or cracked....(the search continues)
its good to have the know-how to replace resistors and things as well...

I have lots of patience and that's where the "Corona" comes in:-)
Did you try bypassing the controller, to see it's running on full speed?
Also did you try to measure any of the components inside the controller?
The big capacitor for example, to see if it holds the charge.
Let me know, how it goes, good luck!

[FIXEROFCARTS]

Im courious, what was cost on parts, I know its not much.

[george7806]

The transistors were about $3.50 a piece and the resistors were about $1 for both. Definitely cheaper than getting a new controller:-)

[FIXEROFCARTS]

nice!

[dwitt]

Originally Posted by george7806

The transistors were about $3.50 a piece and the resistors were about $1 for both. Definitely cheaper than getting a new controller:-)

heh.......yah.....i dont see where they get $300 or more worth of components in there.......(someones raking it in )

[bigefan]

Is there any chance any of this applies to a G19 48 volt controller? I'm totally new to this, but have been told my controller is shot. Thanks..BigE

[george7806]

I have absolutely no idea what yours look like inside, but it worth opening it up, if they say you need to replace it. Mine wasn't made to be disassembled but I cut it open.