Re: motor port problem  you may have blown one of your L293D chips.

try swapping the two chips to see if the problem then migrates to
motor 1.  if it does, then you have blown an L293D.

there is more info on debugging motor problems in the FAQ.  See the
answer to "One of the motor outputs has stopped working" at

  http://el.www.media.mit.edu/projects/handy-board/faq/index.html#motordied

Fred

In your message you said:
> hi,
> i really need help urgently. Currently, I running my robot using 2 DC motor
> on port 2 & 3. I used external power supply to the L293D (pin 8). I did not
> cut the trace. I used Alkaline battery 12V recharagable . when I run my
> robot, it is running smoothly. However,  something went wrong. The port 3
> for the left motor is not rotate anymore. 
> I tried numerous debugging method to see what is the problem.
> 
> Firstly, the outcome of the problem is that the port 3 red LED (reverse) is
> always turning on. When I used the command :
> 
> a) motor (3,50); ==>   red LED and green LED is light up
> b )motor (3, -50); ==> red LED is light up. Green LED is not light up
> the red LED is still turning on for both command . Not the green LED.
> However, When I used command :  off(3) ;   the red LED on port 3 turned
> off.
> 
> I tried to load the "hbtest.c"  and then type " testmotors( ); "  The
> result is that the motor LEDS is begin to flash one at a time , beginning
> with motor 0-green, motor 0-red, motor 1-green, etc. When it reach port3
> green LED, the port 3 red LED turn on all the way without turning  off. The
> red LED stay light up even though the rest of the LED is still flashing
> orderly. The port 3 green LED is still can flash normally. NO damage. Only
> the port 3 red LED has problem.
> 
> Moreover,  i pluck in the DC motor wires into the port 3, the motor is not
> moving. The rest of the port is moving . 
>  
> Please help .Thank .
> 
> rgds,
> phillip
> 
> 
> 

