Mikrokopter Mosfet "POP"

[JLO]

Hi guys I was on the power up for the first time a new all Mk electronics package MK FC 2.0, octo xl power dist board Bl-Ctrlv2.0 pre solder by the dealer,Mk Navi board , and MkGPS
and as soon as I connected a 4S lipo something POP and the distinctive electronic smell and of course the "O NOO from me, after inspection the only visible damage was a hole on 1 of the mosfets on the bottom of the board next to the caps BL-Ctrl #8, I have inspected and inspected all of the solders that I did and I did not see any mistake tomorrow I am calling the dealer but for now my question is has this happen to any one before if so why. thanks guys
View attachment 9886

 

[RotorJockey]

If you caught the smoke that came out of the board, you could put it back, fix the fault and it will work again ... JOKE ...!
My experience (in electronics) is when a chip inside a plastic packaged transistor pops a hole, it is usually a catastrophic short circuit on the output side of the circuit (the device controlled or fed by the circuit) with little or no current control on the input side (often the battery).
I see from the pic there are 3 wires extending from under each FET. Look on and under the printed circuit board (pcb) for solder bridges, chips of solder or other metal where it should not be. Compare the tracks and components around the legs of the FETs (they should be similar) to locate a possibe fault. The component values also should be similar. Where the wire(s) are connected to the pcb should only make contact with the required track/component in each case.
The device that is fed by the FET and its wiring should similarly be checked. If you have or can get a continuity (multi-) meter set on the appropriate range, the above comparison can be more detailed.
This would be the 'first line' procedure. If such a fault can be cleared, its just a matter of replacing the FET with a similar one. This is usually quicker than 'second line'.
The 'second line' option is to send the pcb back to the manuf./supplier for replacement.
I hope this helps - please post the outcome!

 

[Bartman]

do you want the good news or the bad news?

The good news is that it didn't happen while you were flying. Those FET's burn pretty hot and will desolder everything around them when they really ignite. Flames are not out of the question.

THe bad news is that you're probably going to be told it's your fault and that you have to pay for the repair. Maybe not, but probably.

Those caps work well in the position they're in but they have to be bent to not touch the FET's and they have to be secured with a blob of the cheap, clear hot glue that you can buy at craft stores. That first power up is the tricky one. You're usually good for a while if the smoke doesn't leak out the first time.

A possible cause is an excess of solder used to attach the motor wires. Too much solder on the motor pads and you end up transferring a lot of heat into the FET and they end up damaged. Repair of the board by replacing the BL is the quickest and easiest repair. $85 for the BL, and a quick solder job. I've tried repairing the BL's with limited success but have come to the conclusion it just isn't worth the time.

Bart

 

[RotorJockey]

Bartman, what is a BL?

 

[JLO]

Thanks guys I am sending the board back to the dealer so they can replace the BL and test the board o boy 2 more weeks
thanks

Bl = Microkopter Brushless controler or Bl-Ctrl

 

[RotorJockey]

Oh, thanks. Did you have a close look at the board?

 

[JLO]

Yes, under a magnify lamp nothing that would tell me the source of the pop MOSFET

 

[Electro 2]

Usually, a good house rule to follow when applying power the first time to any new power handling device, is to limit current. Use a bench supply with dynamic current regulation or something a simple as a 9v transistor radio battery. If there's a short somewhere, nothing ugly will happen as the supply side simply can't source enough current to do any real damage. Alway did this in a previous lifetime with medium size gimbals for optical and radar systems. Slug each of the supply lines with low-value, hefty, power resistors during first time start up. Then if the gimbal "slammed" to one limit or the other, no damage resulted.

 

[Shaun Stanton]

If you caught the smoke that came out of the board, you could put it back, fix the fault and it will work again ... JOKE ...!
My experience (in electronics) is when a chip inside a plastic packaged transistor pops a hole, it is usually a catastrophic short circuit on the output side of the circuit (the device controlled or fed by the circuit) with little or no current control on the input side (often the battery).
I see from the pic there are 3 wires extending from under each FET. Look on and under the printed circuit board (pcb) for solder bridges, chips of solder or other metal where it should not be. Compare the tracks and components around the legs of the FETs (they should be similar) to locate a possibe fault. The component values also should be similar. Where the wire(s) are connected to the pcb should only make contact with the required track/component in each case.
The device that is fed by the FET and its wiring should similarly be checked. If you have or can get a continuity (multi-) meter set on the appropriate range, the above comparison can be more detailed.
This would be the 'first line' procedure. If such a fault can be cleared, its just a matter of replacing the FET with a similar one. This is usually quicker than 'second line'.
The 'second line' option is to send the pcb back to the manuf./supplier for replacement.
I hope this helps - please post the outcome!

Agreed, MK BL's are real susceptible to being shorted out. Sometimes a small wet blade of grass that gets caught or other debris near the MOSFET's can cause that capacitor to short out. That cap which I believe on the circuit diagram is C9 is a common element that blows out when there is a short between A, B or C MOSFET's. That cap is part of the BEC for the Atmel chip on the board.

 

[DennyR]

Another possible cause is from the use of an aerosol product called Contact which MK sell. Don't clean your boards with this stuff as is does what it says on the tin. It makes contact everywhere and can trigger your FET's at anytime. Hence the name. MK fireworks kit.
Once it soaks in to everything, it is difficult to remove. I have know it work fine until a freshly charged battery is connected. Do yourself a favor and forget MK and get Autoquad-6, nothing else comes close.