Here's what I found out. Seems I have a different board than the one in your link. UM has incorporated a Jumper for Future Upgrades. With this jumper connected it will keep the PCB board Fan running at low voltage at all times. With it Halfway Jumped it will keep it off when the USB is plugged in. I was told they will put a diode in future boards too prevent the fan from running on low voltage all the time.
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ddurant 0
There are 2 big bits to the UM electronics: the Arduino Mega and the RAMPS shield. The RAMPS board looks like this,
http://arduino.cc/en/uploads/Main/ArduinoMega.jpg
.
The Mega is the brains - it's got a CPU and is the electronics bit that runs the firmware and is powered by the USB connection. The RAMPS board, though cool, has no brain and is powered by the power brick.
The LED on the print head is also powered by the Mega so if the Mega is on, the LED should be on too.
The fan on the electronics is connected to the RAMPS board so if that's got power, that fan is on. The Mega may be able to change the speed of that fan but it's really powered by the RAMPS board.
What you're describing all sounds normal to me...
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