broken controller questions

[stevo]

Awhile back, my Crystalyte 36V 20A controller stopped working. I'm not exactly sure why although my LBS suspects water got into it. Anyway, one thing I noticed is that, if the controller switch was "on", even without the battery, when I turned the wheel, there was an incredible amount of resistance (like I had the brake on full). But if I turned the controller switch off (or unplugged the wires from the controller to the motor), then the resistance would disappear and the wheel would spin fine. So I am curious, what could have happened to the controller and how could it cause so much resistance even with no battery hooked up?

As a secondary question, depending on what causes a controller to break, are they sometimes fixable or are they generally toast? The reason I ask is that I am considering sending it back to the vendor for investigation (and possible warranty repair) but if generally, broken controllers are not fixable then I may save myself the postage and not bother sending it.

thanks

 

[icecube57]

I just had a similar senario. Its on of two things. A blown cap. Probably the one that reduces the spikes on the mosfet bust and or two shorted mosfets.

 

[dnmun]

cogging with no battery but controller switch on? but if you turn the switch off it will turn free?

 

[icecube57]

ohhh i re-read it. Yeah that is funky. I didnt have anything like that happen. If the mosfet is shorted it cog wether its on or off. When you unplug the motor from the controller ... It should free up. It also sounds like how my funky GM regen controller acted.

 

[stevo]

Hi dnmun,
Sorry, I realize I posted the facts incorrectly. Ignore my first post.

So to start again,
The battery is disconnected. If I connect the cable with the "rectangular" connector (the one with 3 flat leads), from the controller to the motor and spin the wheel, there is huge resistance (as if I had the handbrake on full). It doesn't matter whether the 5-pin connector (which I believe are the hall effect sensor wires) is connected or not.

It feels like the wheel is running in regen (but I don't have a regen controller).

 

[icecube57]

Sounds like some shorted fets to me. You have to open the controller up and test the mosfets with a volt meter.

 

[stevo]

Thanks icecube57,
can you point me to a tutorial about testing/replacing mosfets? (I don't even know what a mosfet looks like)