Arduino only powers from USB

Hiya. I have Beenplaying around with my Arduino Duemilenove for a little while now and i am having a persistant power problem. The board connects fine via USB and powers up ok but it simply doesnt seem to take power via any other way.

I eventually need to power it with batteries in a robot so i’m testing with an AC/DC converter for now. i have even tried taking apart a USB cable and hooking the gnd and voltage from the converter directly to the pins in the USB connector. Does this seem like a dud arduino or is there something integral missing?

Matt.

Well you need to tell us a little more information. How are you attempting to hook up your external power, what is the voltage and current ratings of your external power source? It needs to around 9vdc or greater with the positive lead to the center connector and ground to the outside shell connector. You can also wire an external proper value DC voltage to the Vin pin and ground pin on the Arduino.

Lefty

thanks for the quick reply but it simply doesnt do anything. my converter is variable voltage so i have been using it to test everything that will eventually be battery. I get a little spark when i touch the +9v and gnd to the arduino pins but no power LED etc. USB cable to computer still powers it though.

when i touch the +9v and gnd to the arduino pins

What pins are you touching the +9vdc and gnd to on your Arduino? And is your variable voltage source have a current rating that is enough to power the Arduino board?

Lefty

I have tried it on the ground & Vin pins (correctly) the 4mm power jack and also a hacked usb cable. The supply is 1000mA.

I have tried it on the ground & Vin pins (correctly) the 4mm power jack and also a hacked usb cable. The supply is 1000mA.

Well it should have worked wiring +9vdc to the Vin and ground pin. However if you ever connected +9vdc via the USB connector then there could have been serious damage done, it's a +5vdc input only, however if your board still works hooked to the PC via USB then you are lucky. I afraid I can't help much further without actually having the board in front of me to troubleshoot with the proper test equipment. There is a schematic drawing avalible on the Arduino site and if you can trace the power circuits with a scope or DVM you should be able to isolate the problem.

Lefty

Silly question perhaps, but you did move the jumper from the USB to EXT setting first?

This is the Duemilenove model. The power is supposed to be automatically selected. Even if that wasnt working for some reason it still wont power from the hacked USB cable.