Smoked BK 9920

[Major Azzwoopin]

Alright guys I got a question. Sorry been away so long. But with winter and all and having a second little one, I've been out of commision. Last Sept I bought 2 9920's and 2 feigao BL motors from Mike. One was for an EMaxx project and the other was for my Savage.
I just got around to and fabricated a motor mount for my savage. Well on Sunday I soldered up the ESC to the motor and put a deans on the battery leads to the ESC. I pulled the pink jumper to program the ESC, and connected the airtronics plug from the ESC into the throttle port on the receiver. (I am using a 6 volt nimh hump pack for receiver and servo power for now) Well when I hooked up the 6S lipo pack the lower right hand capacitor popped (lower left if you look at the ESC from the battery connections with positive on the right) What did I do wrong? The ESC had never even been connected to anything. I was gonna try the other ESC and have PM'd Mike about trying to get the one with the bad capacitor worked on, but am afraid that I did something wrong and don't wanna nuke another ESC.
HELP please..

[sjcrss]

copied from hpi forum ..it sounds like you sent to many volts thru the BEc part of the controller...in order to use a rx pack...you need to disable the bec function on the controller...by either pulling the center wire out of the plug that goes into the receiver.....or by removing the black bec plug on the controller..........try pulling out the center wire and try re-programming it again...you might get lucky.....

[Sylvester]

It needs replacing. When a cap goes, it wont work anymore.

[Major Azzwoopin]

yes sorry for the duplicate post but I posted in the savage section before I figured this area was more appropriate. I looked all over for the black jumper, but didn't want to remove that much heat shrink. After it popped the capacitor, I pulled off enough heat shrink and found the black jumper. I wouldn't think that a 6 volt pack would have enough ooomph to pop a capacitor on the BEC circuit though. Everything on that circuit should be rated at that voltage. What is the advantage of using a hump pack instead of the built in BEC function of the ESC?? Mike said in his programming the BK ESC section that if you ran more than 10 cells you should either use a hump pack or a BEC. I would think that the ESC should be able to step down the voltage for output to the receiver and power the servos. Maybe a amperage to power the servos??? So If I use a external BEC or a hump pack I need to remove the black jumper? correct? this eliminates the output or bleedback of voltage into the ESC from the recevier pack? or I could remove the hot lead from the airtronics connection into the recevier pack from the esc.

[Gustav]

Leaving the jumper on shouldn't smoke the controller just like that,in fact don't they suggest using both together in certain circumstances?

I wouldn't use the internal BEC on a MT,it's more a convenience feature for low cell counts,it creates more heat,which needs to be dissipated so the controller is more efficient when you don't use it.It doesn't sound to me like you did much wrong at all,remove the black jumper if you're using a rx pack or ubec though.

[Major Azzwoopin]

I want to try the other 9920, but now I'm scared that I will fry it.

[skellyo]

What likely happened is that the 6S lipo voltage was higher than the working voltage rating of the decoupling capacitor used on the BEC network. It's likely a 15V or 20V cap, so 6S would definitely exceed that and possibly cause the problem you saw.

[MetalMan]

BK uses 50V capacitors...

Mtroniks supplies a 16V capacitor (10,000uF!) with their Truck controller, and I use it with 4s Lipo (16.8v when fully charged) all the time.

[Major Azzwoopin]

SOOOO Any ideas on what I should verify before trying the other controller??? I will also just try 14 cells to start out. I will then go to 5S lipo. before I retry 6S.

[skellyo]

Originally Posted by MetalMan

BK uses 50V capacitors...

Mtroniks supplies a 16V capacitor (10,000uF!) with their Truck controller, and I use it with 4s Lipo (16.8v when fully charged) all the time.

Thanks for the info MetalMan.

I guess another possibility is that the cap was installed backwards from the get go. I'm not sure what kind of testing they do on these before they ship out, but being an EE myself, I know those sorts of things can and do happen. Trying to put the smoke back is the tough part.

[coolhandcountry]

I was thinking the backwards mount to. I seen them do wires on another esc. I guess a cap is just as easy. May have a sabatoger in the factory. :D

[Major Azzwoopin]

So in other words, I should give the other one a try and hope I don't get any capacitor spit on me. I will let you all know how it goes. I will try 14 cells and remove the black BEC strap. I might even remove the hot wire from the connector between the receiver and the ESC to be extra safe.
Capacitor spit is really nasty stuff. Unlike people spit it doesn't make you angry just makes you get a real crappy hole in your belly feeling when it happens. LOL

Sorry to hear about the smoke. I feel your pain.
My 12020 would burn one leg off every time I tied to use it. Make sure you send the burnt one back to Mike. Hopefully he can get it fixed via warranty.

Good luck bro.

[Major Azzwoopin]

I tried the other 9920 I had and whallllaaa!!!!!!! worked like a champ. Now I need a real strong slipper. 6S is real strong. The metal spur I'm using sounds real weird with the brushless. Hopefully Mike will answer my PM soon so I can return this other ESC and get it fixed. Plus my little boy isn't real smooth on the throttle. Hard on then off, and again, and again he likes the wheelies and seeing the gravel and dust fly.

[coolhandcountry]

He is no different than me. I love wheelies and gravel fly.
Try to email mike. It seems to work better than pm. He don't get on a great deal cause he kind of busy.