L293D Motor Driver Module +5V onboard problem

[okbro]

I had a working bluetooth controlled car made with arduino uno, L293 motor driver shield. After many months, i tried to use it but now there is no +5V on the board which was used to supply power to the bluetooth module HC-05. I checked and the power supply from 3 li ion batteries is 12.6V while the onboard +5V shows only 0.5mV?

any ideas?

 

[danadak]

Youi have a schematic for car and/or board you can post ?

Also well focused pics top and bottom of board ....


Regards, Dana.

 

[okbro]

there is nothing else, i have just connected to shield on top of the arduino board and applied the power via battery and checked the pin voltages...i also checked with another shield(the one shown is newer) but this board is also showing only 350mV instead of 5V.

 

[danadak]

Maybe construct a schematic by hand from scratch ....

 

[aliarifat794]

There is an on board 5V line. You have to solder male connector if needed. If the 5V line is showing only a few milivolt current please check if the batteries are fully charged. Also check if there is any short circuit occurring when you are connecting the shield with the Arduino.

 

[okbro]

as i said in the beginning i checked the batteries and it is showing good ~12.6V and that is exactly why i am wondering why there is no voltage on the +5V pin?i checked the schematic of the shield and i can only imagine if the shift register IC is damaged(Kaput)

 

[rjenkinsgb]

The power jumper on the motor shield is supposed to link the motor shield power input to the power input on the Arduino, so it uses the 5V regulator on the Arduino to create the logic 5V supply.

See page 37 of the motor shield maual:

https://cdn-learn.adafruit.com/downloads/pdf/adafruit-motor-shield.pdf

If no 5V, either there is a bad connection somewhere, the 5V reg has failed, or its output is shorted (in which case it will be hot!)

 

[okbro]

hi thanks,
i know the functionality of the power jumper. but i think the problem is not there, but the+5V pins(and the ground pins) that i had soldered and it was working just fine. Now I tried to trace the schematic(also previously done) but cannot find where the battery supply(12.6V) is converted and connected to the +5V pin is connected. But the battery supply voltage must be connected to the power jack circuit somehow and there must be voltage converter IC which is not on the L293D shield schematic. So?

 

[rjenkinsgb]

The 5V regulator is on the Arduino, as shown in the schematic page I linked that has the power jumper.

The cross-connection with the motor shield is via the (red) VIN & +5V pins, and the (black) GND pins on the Arduino connector diagram, here:

https://docs.arduino.cc/resources/pinouts/A000066-full-pinout.pdf