Juniper MX240 Hardware Manual page 249

5. Switch on the dedicated customer site circuit breakers to provide power to the DC power cables.
6. Check that the INPUT OK LED is lit steadily green to verify that power is present.
7. If power is not present:
Verify that the fuse is installed correctly, and turn on the breaker at the battery distribution fuse
board or fuse bay.
Check the voltage with a meter at the terminals of the power supply for correct voltage level and
polarity.
8. Wrap and fasten one end of the ESD grounding strap around your bare wrist, and connect the other
end of the strap to the ESD point on the chassis.
9. On each of the DC power supplies, switch the DC circuit breaker to the center position before moving
it to the on (—) position.
NOTE: The circuit breaker may bounce back to the off (O) position if you move the breaker
too quickly.
10. Observe the status LEDs on each power supply faceplate. If a DC power supply is correctly installed
and functioning normally, the PWR OK, BRKR ON, and INPUT OK LEDs light green steadily.
11. If any of the status LEDs indicates that the power supply is not functioning normally, repeat the
installation and cabling procedures .
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