help with brushless rc setup

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help with brushless rc setup

Postby def215 » Tue Mar 08, 2011 7:48 pm

i ran into a problem today. while taking a ride today, my setup was working flawlessly. then all of the sudden it went berzerk and stopped working correctly. i was hoping someone could chime in and shed some light on my problem.

my setup is:
-exceed brushless monsterpower 46 (50-55 670kv)
-mystery 80A brushless controller
-servo tester
-22.2 v 6ah lipo

this setup is a friction drive with a 0.650 inch roller.

so the problem is that with no load, the motor will run up to full speed without a problem. but when i actually try to use it, it seems to not wanna put out the full power, and i think its cogging(not sure what to look for when it cogs). then when i try to run it up, it will try to go the opposite direction very roughly. i tried to look at the controller, it doesnt look like there is anything wrong. but while its on and running, some chips on the board get excessively hot. here is a picture of it:
Image
sorry, i know, crappy pic but i know what chips are giving me trouble.
the chip in the red box is a TA7805F Bipolar Linear Integrated Circuit. http://www.datasheetcatalog.org/datasheet/toshiba/4143.pdf
the chip in the green box is a IR2101S(below that says 0522, does this mean anything in particular?) HIGH AND LOW SIDE DRIVER http://www.irf.com/product-info/datasheets/data/ir2101.pdf
the chips off to the left and right of this one are similar. im guessing its the drivers for the 3-phases.
these two chips seem to heat up signifigantly. im not sure what is going on with it. i tried to check the motor for shorts or burnt windings but i dont see anything wrong with the motor at all.

any help with this is appreciated.
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Re: help with brushless rc setup

Postby def215 » Wed Mar 09, 2011 9:48 am

Ok. So I removed the chip in the green box, the ir2101s and It powered up. And the motor spins up, but it still acts the same way. Does this mean that hi/lo driver chip is bad or could it be something more than that?

Can anyone help me out and at least drop me a hint or a clue maybe, to what could be wrong?
Project: E-BMX - Completed, debugging.
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Re: help with brushless rc setup

Postby bobc » Wed Mar 09, 2011 10:39 am

I fear if the gate driver chip is getting hot it's gotta mean at least one fried FET (one on that phase)
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Re: help with brushless rc setup

Postby def215 » Wed Mar 09, 2011 11:58 am

aww crap. i was hoping not to hear that. at least i have a clue to what might be going on. thanks bobc. i replaced that ir2101s with another one that i had that came off of a controller with blown fets and it does the same thing.

also, i did continuity on the fets and the middle leg, the affected one, has 4 out of 6 fets that have continuity between the first and middle leg of the fet. all the rest of the fets have no continuity between any of the legs. there is also a high pitched buzz coming from the controller. i dont recall this noise on it at all. i put the controller and motor on an oscilloscope and it doesnt look like anything out of the ordinary. the same thing shows for all of the legs.
Image
it might be time for a new controller...
Project: E-BMX - Completed, debugging.
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