I've an Arduino Duemilanove board clone with power issues. I want to get my hands dirty and repair it.
Here is a schematics that I use: http://arduino.cc/en/uploads/Main/arduino-duemilanove-schematic.pdf
Issue description: When powered from USB the +5V is about 3,8V, when powered from DC jack -- I have 5V on +5V line.
That's not USB port issue, I've tried a couple of PC and standalone USB chargers.
What I've measured when powered from USB:
- I've 5V on USB jack
- I've 5V before and after fuse F1
- I've 5V on T1's D pad
- The voltage drop on diode inside T1 (measured from D to S) is about 1V
- When powered from USB I've 2,56V on G pin of T1 (I suppose it should be low?)
- When powered from USB I've 3.3V in Vin
1. Is voltage drop on T1's D-S junction in 1V a correct value? If anyone can measure the voltage drop between 2 and 3 pin of T1 on working board and post results that's will be great!
2. When I look into schematics I assume that when board is powered from USB I should read 0V from Vin. Can anyone check on their board?
3. What voltage is on your +5V line when powered from USB?
4. Is there anything else I can check?
Thanks in advance!