ST750
G
ENERAL
H
ANDBOOK
667/HB/33750/000
Page 104
Issue 6
Where an Internal Manual panel is fitted, it may be removed directly by removal of
the screws holding it to the 19 inch panel; it may be easier to remove the 19 inch
panel from the rack first. No sealing is required on refitting.
7.4.8 Replacement of Expansion I/O or OTU PCB
Removal of the I/O or OTU PCB may be done once the Mains to the ST750 Rack
Assembly has been isolated at the master switch, the 64-way Phase Control ribbon
cable has been disconnected from the CPU and the hinged front plate has been
opened.
Ensure that the replacement PCB has the correct firmware and PLD fitted at the
correct variant and issue. Refer to the Works Order Specification for details.
The I/O or OTU PCB is removed by removal of the screw fixings (4 off) which secure
it to the inside surface of the hinge plate. Ensure all the cables are fully
disconnected before the board is removed, and fully inserted following the
replacement of the board.
7.5 REPLACEMENT OF MAINS POWER SUPPLY UNIT
The spare Mains Power unit is provided as part of the Power/Phase Assembly. It is
not necessary to replace the whole assembly if the power unit has failed, providing
the failure has not damaged other components.
The Mains PSU may be removed once the following have been carried out:
•
The Mains to the ST750 Rack Assembly has been isolated at the master switch
•
The 64-way Phase Control ribbon cable has been disconnected from the CPU
•
The hinged front plate has been opened.
Remove the cables and connectors connected to the PSU, then release the nylon
mounting pillar clips that attach the PSU to the heatsink cover of the Phase Drive
PCB. The clips are retained on the heatsink cover by means of an integral clipping
mechanism on the other end.
When the PSU is replaced, ensure that the clipping mechanism of the mounting
pillar is fully engaged and all the cables and connectors are securely fitted.
Re-assemble the Rack Assembly.
7.6 REPLACING OTHER COMPONENTS
Only approved spares must be used when replacing any components. Use of any
other components may invalidate the Type Approval of the equipment.