Toshiba CTX28 Check the -24 Volt Circuit Breakers, Circuit Breaker Location and Slot Assignments

Rack Mount Cabinets

Power Supply Unit (BRPSU672A)

Check the -24 Volt Circuit Breakers

The BRPSU672A provides four -24v circuit breakers as shown in figure above. If a low resistance between –24 volts and ground exists the circuit breaker will trip. Usually the front panel DC green LED indicator will turn off but not always. Also if AC power is recycled the DC LED indicator may turn back on – even if the –24 volt circuit breaker is tripped.

Circuit Breaker Location and Slot Assignments

•The circuit breaker 24V1~24V4, located directly below DC-out cable, protects the cabinet slots as shown in the Circuit Breaker assignment table.

Reset Circuit Breaker

1.A defective PCB or an external short on the MDF may cause the circuit breaker to trip.

2.If you suspect that a –24 volt circuit breaker has tripped, try to reset it by:

•Turn the power supply DC power switch off and unplug the power supply AC power cord from the AC outlet – the inside of the power supply has exposed voltages.

•Gently press in each circuit breaker and listen for or try to feel it click. If the breaker was tripped, you will hear or feel it click back to the set position.

•If the circuit breaker resets, pull the PCBs and check for MDF shorts associated with the slots assigned to the tripped circuit breaker. Remove any defective PCBs and MDF shorts.

•Restore power and verify the system is working normally.

3.Replace the power supply if the circuit breaker continues to trip and a defective PCB or short cannot be found.

Rack Mount Cabinets

Strata CTX I&M 06/04 5-29