I've recently bought an Arduino Pro Mini, the 3.3V and 8MHz version. The first time I powered it, using the VCC pin, all worked. But, as soon as I attempt using the RAW pin instead, nothing lights up... Is my regulator broken ? Or is this a typical issue ?

  • What is the power source you are attempting to connect to the RAW pin?
    – Majenko
    Commented May 22, 2015 at 20:32
  • @Majenko It's an unregulated 5V source
    – Spirine
    Commented May 22, 2015 at 20:34
  • 1
    Check there is solder on the solder jumper SJ1
    – Majenko
    Commented May 22, 2015 at 20:36

1 Answer 1


I am not completely familiar with that specific board, but according to the schematic there is a solder jumper which is used to isolate the RAW voltage regulator from the rest of the system "for low power applications".

enter image description here

I don't know off hand if that comes pre-soldered or not, but check it to make sure it is connected, otherwise the RAW input will do nothing.

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