Let's Make Robots!

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.

Connections:

  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?

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

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. 

http://letsmakerobots.com/node/30702

there's not much on it but maby you can message robotfreak for more info

i sent him a message. 

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 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 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.