View Full Version : Did I damage my controller ?

19 August 2016, 1220
Hi guys,

need some guidance here,

i was doing some tests today on my electric motorbike, Curtis 1238-7601 and AC-20.

At some point 2 of the cables going to the motor touched together for a brief time while the motor was spinning slowly (no load). At the same moment my main fuse blew out.

I'm trying to find out if i have damaged my motor and/or controller.

Here's what i have measured so far:

i've disconnected the controller completely from motor, battery and harness.

on the motor side, resistance reads infinite between phases and face plate, that seems ok.

On the controller, i measure an infinite value between all phases and B+, but on B-, 1 phase reads a large value, but on the 2 other phases (seems to be the ones that have touched) i measure 0. That's not good, right ?

Resistance reads infinite between B+ and B-

I'm able to connect to my controller using the Curtis software but i have not replaced my main fuse yet and the motor is completely disconnected from the controller (3 phases and temp sensor/encoder). I see these 3 error codes:
- Pot 2 wiper high
- Precharge failed
- Motor temp hot cutback

Do you think my controller is damaged ? or the motor ?

Can i safely re-install the main fuse ? can i re-connect the motor phases ?

thanks for your precious help,

I have also contacted tech support of electricmotorsport.com where i bought the kit.

20 August 2016, 0841
Anybody knows how to open a Curtis 1238 controller ? Mine is out of warranty anyway. So it thought i might as well look inside. If i'm lucky it's just a couple of caps blown off. Or the pre-charge resistor failed.

The only 2 error messages left i have are:
- Precharge failed
- Motor temp hot cutback

For the first code, Curtis manual mentions :
1) External load on capacitor bank (B+ connection terminal) that prevents the capacitor bank from charging
2) See Monitor menu >> Battery: Capacitor Voltage Set: Precharge failed to charge the capacitor bank to KSI voltage

I've searched on Google how to open the controller, not very clear, some people have done it, seems i have to remove the 5 brass lugs on the cover, but it's not clear how to remove them. AFAIK, there are no screws to be removed on the controller.

21 August 2016, 0603
To answer my first question: my controller is definitely damaged, the power board is fried.

You can see it in the attached video. It shows also how to open the controller, it's rather easy. Of course you have to be very careful, the caps inside could still be charged and kill you. If you don't know why/how, then don't open it.

Lessons learned:
- don't let the phases of your motor touch together
- don't install your main fuse if your contactor is closed, this will create a rush of current inside the controller caps and huge spark.

Now i need to buy a new 1238R-7601 controller.

Video here:


Electro Flyers
21 August 2016, 0832
Bummer about the controller. The magic smoke is so difficult to put in and so easy to let out! Your terminal removal technique puts a lot of stress on the circuit boards the terms. are attached to. Better to use a puller that pulls on the outside and pushes on the threaded, inside of the terminals. These guys could fix it: http://www.fsip.biz/index.html , but usually it's very expensive.

21 August 2016, 1113
I'm sorry about your board but thanks for the really useful info and follow-up!