Melex 252 Curtis controller 1204 bad?
 

I have a melex 252 from early 1990's.
It was working as usual, then one day i was putting it in reverse and it pushed the throttle and it only barely moved, didnt matter how much I pushed the throttle. I left the cart and the next day it was working as usual. The day after that I could go maybe 10 meters and then it stopped. Hasnt worked since.

I* have measured all the microswitches and they seem fine(solenoid clicks when i push the throttle).
*Potentiometer starts at 0k and when i push the throttle it goes seamlessly up to 5k.
*F&R switch has been dissasembled, cleaned and measured and seems ok.
*I have put a 12v battery directly to the motor and it runs fine.
Yesterday I removed the Curtis controller since that seems to be the one thing left.
It looked like this:
https://i.ibb.co/jJGNtpF/curtis-1.jpg
https://i.ibb.co/rk2k3fN/curtis-2.jpg

Is there any test i can do with the controller out to see if it is ok?
Do you think the corrosion(or whatever it is) could be the problem?

Regards,

Re: Melex 252 Curtis controller 1204 bad?
 

Best way to test the controller is in the cart.

Clean the heck out of that controller. Put it back and see what happens.

From the looks of it, I would say that controller has performed 30 years of hard labor and deserves a retirement, but looks don't tell everything.

Re: Melex 252 Curtis controller 1204 bad?
 

Ok, i found som test protocols for in the documentation from curtis.
Just gonna clean this up and put back in and see what happens.
Yes its an old cart and its been standing outside for 10+ years. My friend then put 48v batteries in it and it started to burn. He gave it to me and I put 36v batteries in and worked fine for a year until now...

Re: Melex 252 Curtis controller 1204 bad?
 

Looks to me like bad cables caused the heat that discolored the controller contacts. With any luck that is all it did. The bench test in the documentation will tell you allot, of it checks OK you need to replace all the cables with soldered connectors. In the process of doing that on my 512, looks to me like the Melex cables are just crimped and not soldered, time and corrosion makes for high resistance which makes heat.

If you do determine the controller is bad I would be interested in getting my hands on it. I am looking for a few bad 1204 controllers to see what it actually takes to repair the durn things.

Re: Melex 252 Curtis controller 1204 bad?
 

I cleaned the controller up, and all other connections i could find. Still doesnt move.
I measured the throttle potentiometer, it has 3 cables coming out of it.
Black, blue, and green.
black and blue is going in to curtis controller, green is going to micro switch in F&R switch and also routes to the back somewhere on the cart.
My measurements with keyswitch off:
*Black and blue=No throttle 0kOhm, Full throttle 5.03KOhm. No hops or "dead zones".
*Black and green=No throttle 52.5k Ohm, Full Throttle 52.5kOhm
*Blue and Green=No throtte 52.5k Ohm, Full throttle 59.1K Ohm.
https://i.ibb.co/SvPkTCm/pot1.jpg
https://i.ibb.co/cQ7HRF8/pot2.jpg

Anything out of the ordinary?

Re: Melex 252 Curtis controller 1204 bad?
 

Red, black and blue are all correct as shown. Red should go to 36v when you step on the pedal.

Re: Melex 252 Curtis controller 1204 bad?
 

Ok, great!
About the resistances, is there anyting odd?
Regards,

Re: Melex 252 Curtis controller 1204 bad?
 

The black and blue wire resistance is correct. I do not know the purpose of the green wire.

Re: Melex 252 Curtis controller 1204 bad?
 

I checked voltage at Controller B- and Battery B+ terminal. Only 2.6v. So my conclusion is that batteries are discharged or the connections are bad somewhere. To rule out discharged batteries I've removed the batteries and are now charging them one by one. I starting to think that maybe the 36v charger that belongs to the cart is not charging correctly. I'll post again after I charged all the batteries.

Re: Melex 252 Curtis controller 1204 bad?
 

Charged all batteries one by one. Batteries are OK.
Voltage between B+ and M- on controller is 0 with pedal up, and 0 with pedal down. New conclusion is that controller is bad. Gonna check for a new used one.
When I have the time i'm going to try to open up the controller and check if there is anything to do with it.
Anyone who has ever opened up a curtis 1204 and know what is the usual problems is?
Regards,