U7 got fried for some reason :(

I just got my Dagu 4 Channel Motor Controller, already a small part gave some smoke and one motor channel is not working anymore.

All four wheels were turning at the same time before the channel4 got fried.


  VCC to Arduino 5V

4 PWM on the motor controller to 4 PWMs on the Arduino uno.

All grounds on both  controllers where connected.

6*1.5V Alkaline AA to Vbat on the motor controller(connected after all the other connections).

After uploading a simple code with PWM set to 75, all wheels were turning until smoke came from U7 chip and i unplugged everything.

Repeated the same thing again, all 3 motors are still working, so why did U7 burn, i have no idea. 

Any ideas?

Can you post a sharp picture

Can you post a sharp picture of your setup? Where we can see the wiring?

The wiring is very basic,

The wiring is very basic, but i dont have a camera today. I can explain the wiring: 

the arduino is connected to the computer via usb, the 5V from arduino goes to the logic on the motor controller. All 4 motors are connected to their power source on the motor controller (the motor controller is connected to 6 AA 1.5V batteries). 4 PWM from the arduino are connected to the PWM of every motor. All grounds are connected to one main ground. nothing more nothing less. 

All 4 motors were connected identically, only one stopped working while the others are still fine. 


i sent him a message. 

Hi ziplague,it looks like

Hi ziplague,

it looks like the same problem that happened to me. Unfortunately I don’t know the cause for it. Only a vague suspicion: Maybe a loose logic power supply connector was the cause. I have used Jumper cables with round pins, that didn’t give good contact. Now I use the srew terminals. No more problems so far. 

I used the screw terminals

I used the screw terminals too. Weird. Any ideas as to how can i fix it, bypass it or replace the U7 chip?

Because I need only 2 out of

Because I need only 2 out of 4 motor drivers I have no urgent intention to replace the defect one. Don’t found the SP8M3 at my favorite distributors list, too. A replacement part could be the IRF7319. But in this case you should replace both half bridge ICs U7 and U8.

Replacement of the chip is not a big deal if you know how:

  • Use a cutter to cut off the pins of the defect IC.
  • Than remove the pins with the solder iron.
  • Than you can solder the new chip.
  • Hold it down with a pincette and solder one pin first.
  • If everything is in the right place continue with the other pins

Edit: I have some IRF7319 chips here, so I will try it by myself.