6 Maintenance
40 Keysight N8900 Rack System Installation Guide
The Keysight N8900 Series Rack System has locks on the front and
back doors. Only authorized persons should have access to the keys.
- The lock on the front door is designed to prevent
unauthorized access to the front panel controls. Access to the front
panel controls may be necessary during normal operation. Opening
the front door does not present a safety hazard.
- The lock on the back door is designed to prevent
unauthorized access to the cabinet during operation. If the back door
is opened during operation, a safety switch shuts disconnects AC to
all power supplies.
The interlock switches on the back door do not completely disconnect
the AC mains from all components and connections inside the rack. AC
voltage is still present at the main terminal block, the line side of K1 and
K2, circuit breaker F7, and the auxiliary power supply.
Switch off the disconnect device before servicing.
To service the rack system you must turn off the external disconnect
device to completely disconnect the AC mains from the rack system.
This disconnect device must be installed by the customer. Refer to
External System Disconnect.
Attach a tag to the rack system to indicate that the cabinet has been
disconnected from the AC mains for servicing.
All troubleshooting must be made by qualified personnel who are aware of the
hazards involved. Improper actions can cause fatal injury as well as equipment
damage. Refer to the Warning under Lock-Out Tag-Out.
If there is no power to one or of more of the power supplies:
1. Check that there is power available at the AC mains.
2. Check that the external disconnect device is on.
3. Check that the rear cabinet door is closed.
4. Check that the emergency stop switch is pulled up.
5. Check that all of the front circuit breakers are up (on).
6. Open the rear door and check that there is 24 VDC at the output
of the auxiliary supply. This supply powers the main K1 relays.
7. Troubleshoot the AC portion and the interlock portion (orange)
of the rack system according to the wiring diagrams provided.
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