2013/03/31

Soldered wire onto side of D19 nearest L24 on DCRC33 in order to hook up external DC power supply. Checked DC power output was 48 V with multimeter. Then hooked up other multimeter in series with DC power supply to act as ammeter. Positive lead from DC power supply to ammeter and lead from ammeter clamped onto wire soldered onto the board. Negative lead from DC power supply connected to PGND1 test point on DCRC33.

Turned on DC power supply with board hooked up as above. Potential difference across power supply unsteady. Both +5A and +5.5 LEDs started flashing. No other LEDs turned on. Current drawn was 9 mA. Increasing voltage slightly made no difference. Seems as though not enough power was being delivered to board. Connected DCRC to DAQ computer without going through PoE supply, but board's presence was not registered.

Unhooked DC power supply and tried to power up DCRC33 using PoE supply, which was successful. Cannot explain why external DC power supply resulted in the behaviour witnessed above.