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Topic: Arduino UNO won't power on via USB (Read 7322 times) previous topic - next topic

jchiar

Hi I just got my Arduino UNO. When I plug in via USB, the board doesn't light up the power LED green and doesn't show up under the PORT>

Any idea why? If I power via a daughter board and 3.7v battery it does..

Budvar10

It could be caused by several things and it is little bit advanced for skills. Look at the schematics. Fuse on USB power input. It is reversible fuse so some problem (short circuit, overloading...) persists or the fuse is damaged. Next is MOSFET for switching between USB and jack power. Maybe it has gone or there is switching voltage problem from comparator. It compares 3.3V from onboard regulator against to Vin. With the multimeter would be able to detect problematic part.
What is a daughter board and how is the battery connected? Please be more specific.
Arduino clone with ATmega1284P   http://forum.arduino.cc/index.php?topic=277260.0

weedpharma

Let's start at the beginning.

Have you tested the USB port on some other device?
Have you removed all other connections?
Have you done any voltage checks?

Weedpharma

septillion

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I want x => I would like x, I need help => I would like help, Need fast => Go and pay someone to do the job...

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jchiar

It turns out that the board had a hardware mod from the class i am attending.. I think they removed the FET.

septillion

Only reason for that I can think of is they wanted to power the Uno with 5V (Uno is bad at that...) But yeay, without mosfet, no power.
Use fricking code tags!!!!
I want x => I would like x, I need help => I would like help, Need fast => Go and pay someone to do the job...

NEW Library to make fading leds a piece of cake
https://github.com/septillion-git/FadeLed

karthikeyan_aero

Same happened to me on Arduino due. I had connected to my xbee and it wont power on when connected via USB but will power on if I use separate battery source. then I removed my xbee. Then it worked after that I connected my xbee !! Wierd

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