Service Manual

GSM-204-523
Replacing a thermal management system (TMS) unit
31st Oct 01
Maintenance Information: Horizon macro outdoor
68P02902W04-A
CONTROLLED INTRODUCTION
Maint. 3–9
Removing the
TMS unit
To remove the TMS unit:
1. Remove the TMS front access panel at the base of the cabinet.
2. Shut down the TMS by switching off the TMS FANS at the dc circuit
breaker panel and the TMS heater ac circuit breaker at the number 2 ac
power distribution box.
CAUTION
Care must be taken at all times to avoid cable damage
caused by abrasion as cables pass through cabinet
apertures.
3. Disconnect the following TMS cables:
– The ac cable from the plug at the front right of the power supply
enclosure.
– The dc cable from the connector at the front left of the power supply
enclosure.
– The alarm cable from the connector PL5 at the alarms interface
board.
4. Feed the cables through the aperture into the cable well and tie them
safely out of the way.
5. Disconnect the earth bonding cable from the TMS unit.
6. Remove and retain the two TMS securing screws and washers, on the
front of the TMS unit, using a crosspoint screwdriver.
WARNING
The TMS unit can weigh up to 40 kg. Handle with care
and observe proper lifting precautions.
7. Pull the unit forwards, using the front two built-in handles, lowering the
front edge to ease pressure on the seals.
NOTE
The TMS unit is supported by rollers at the rear (see
Figure 3-4). These run on rails in the bottom wrap of the
cabinet.
8. When the TMS unit is fully withdrawn, carefully lift it out of cabinet, using
the built-in handles on the sides and place it on a dry surface in a position
suitable for further work.