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The power (red) LED on my pi will not light. It was working fine, but then suddenly, while I was using it, poof! At first it blinked occasionally, now it just won't turn on. The power supply was as it was when everything was functional. BTW I was using the pi to test some code where the GPIO pins were connected to a h bridge, which was connected to some DC motors and a 9v battery.

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    How do you know the power supply is fine? Do any components on the Pi now get very hot? Does the Pi boot? Can you carefully measure the voltage between the ground and 5V pins on the expansion header? Ditto between ground and the 3V3 pins? What model Pi do you have? – joan Jul 23 '15 at 16:53
  • I am using the model b+, the central component gets very hot and the pi will not boot. I am not sure I have the equipment to measure the voltage. – Vedant Varshney Jul 23 '15 at 20:18
  • I am afraid that sounds terminal, it seems like the main chip has blown. – joan Jul 23 '15 at 20:21
  • So do you think I should buy another one? Is there a way to fix this? – Vedant Varshney Jul 26 '15 at 10:09
  • I think you will have to buy another. It sounds like the SoC has blown. I know of no way of replacing that for less than the cost of a new Pi. Even if you did replace the SoC (unlikely as you can't buy them) other components will probably have blown as well. – joan Jul 26 '15 at 10:17
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This happens when you overload the pi or there is insufficient power. This could be solved by increasing the input current >2 amp and powering up other peripherals using an external power.

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From your comments you might have a motor driver board similar to this one.

L298N based motor driver board

You should only connect Pi gpios to the pins labelled ENA, IN1, IN2, IN3, IN4, and ENB.

Behind ENA/ENB are jumper pins marked in red.

These pins carry 5V and should NEVER be connected to a Pi gpio.

They are a convenience. If you do not want to have ENA/ENB under software control you can enable ENA/ENB by connecting a jumper between the jumper and enable pin (as shown in the image).

  • Oh... thanks. So was that the problem? – Vedant Varshney Jul 30 '15 at 11:49
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If the red LED does not light then either the power supply itself is bad (which you say is not the case)

or

perhaps the internal voltage regulator is bad.


The first step I would take is a reading at the 5V pin. Make sure the power is actually making it through.

Then I would test the 3.3V pin.


Botttom line: The Red LED should light if there is sufficient 5V power.

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