Curtis 1219-4860 PMC controller repair

[GriffinRU]

Hello RC-Monsters,
Long time no see - I plan to come back again :)

This time, would like to share with you recent Golf cart (Cushman Hawk) Curtis controller repair - upgrade / mod (not like mamba Mod but might be cool to check...)

Didn't capture entire process, but in the middle pull the camera out and of we go...

What was wrong or how we break it:
-start with replacing brake pads -> end up with blown controller (quick switch from FWD to REV while 2000lb cart was moving wasn't a good idea, but smashing into other car would be worth... :)
So, upon restart 3+1 error code, stating your motor locked or drivers out - let me guess Big DC motor vs FETs - you got an answer.

Taking controller apart:
-it was easy (after removing from golf cart) rear panel was lost some time ago, so it was clear which screws to loose and what to push...
-once you have "monster" (by 99 standards) board assembly out all you need is to separate CPU board from FET's board
(Sounds so familiar, right)
-10-pin header to unsolder, 4 plastic standofs and black compound to break:


-no pictures on how to remove FET's - sorry
but here they are:


NEXT step - to Find replacement for 1998 FET - I selected IRFB4410ZPBF MOSFET N-Ch 100V 97A TO-220 -> close enough - better part - cost/availability - 28 fets

Note: replace them all with the same part!

Other parts like CR4180R diodes (more like MR2500) and lots of 1000uF 68V caps were checked and no problems were found.

Note: DO NOT TAKE EVERY TO-220/DIODE PART OF THE BOARD - TO PRESERVE HEATSINK SPACING!!!

-Complete FET's replacement and clean-up:



to be continued...

[GriffinRU]

Check for spacing and preserve heat sensor...

[GriffinRU]

- deburr and apply heatsink grease (not sure why but OEM (CURTIS) didn't use any heatsinking compaund... maybe it wasn't available in late 90 or whatever was another reason... 40A can sink through screw no problem but poor heatsinking might cost you some - especially for diodes...

[GriffinRU]

-Solder in CPU board (check driver fets)
-Apply compaund to seal CPU board and the rest of controller
-Install inside golf cart

Result:
$60 in parts for $600 controller

28 FET's 97A each -> still better than 600A

First weekend - works - I will keep you posted.

-Artur

[BrianG]

Haven't seen you here for a long time. Nice repair job!

Originally Posted by GriffinRU

...not sure why but OEM (CURTIS) didn't use any heatsinking compaund...

IIRC, normal thermal compound is electrically insulating and if they are using the tab of the FET as one of the conductors, then it would be like adding resistance.

Could also be related to the environment that the controller is meant to operate. Maybe the TIM stuff back then had some issues with certain temps or humidity levels making it more of a thermal hindrance than help.

[Arct1k]

Great to see you back and up to your old tricks. Your action on the mm was ledgendary.

[GriffinRU]

Originally Posted by BrianG

Haven't seen you here for a long time. Nice repair job!



IIRC, normal thermal compound is electrically insulating and if they are using the tab of the FET as one of the conductors, then it would be like adding resistance.

Could also be related to the environment that the controller is meant to operate. Maybe the TIM stuff back then had some issues with certain temps or humidity levels making it more of a thermal hindrance than help.

Hey Brian,
You are correct about electrical contact, but they got it wrong from the beginning, given their heatsink configuration they could end up with FET's leaning away from heatsink if it was assembled not strait or due to heat expansion. They should use special clamps to keep FET's at contact and you can tell by the oxidation behind FET's and diodes tabs...
I think for 40A per FET (OEM) mounting screw was more than enough and use the rest for heatsinking or at least 1/3 by 2/3 - large area under die.

Thanks for feedback, and glad to be back,
-Artur

[GriffinRU]

Originally Posted by Arct1k

Great to see you back and up to your old tricks. Your action on the mm was ledgendary.

Thank you,
What's new and great? I think I need to get a toy for my 5-year old...
-Artur