Nortel Passport 15000, Hardware Installation And Maintenance, Page: 547 / 874

Chapter 17 Hardware procedures 547
Passport 15000, 20000 Hardware Installation, Maintenance, and Upgrade 5.2S2
• You need these specialty tools:
— a medium non-magnetic one-piece Phillips screwdriver with a very
short shaft
— a flashlight to see through the spinning fan blades at what your hand
is touching inside the cooling unit
• The air filter will prevent a dropped screw or tool from reaching the
powered processor cards below the cooling unit.
• The temperature sensors for the lower (rear) cooling unit are located
inside the cooling unit.
Procedure steps
1 Put the replacement temperature sensor above the circuit board, and put
them inside the cooling unit where the old one was removed. Note the
orientation of the screw holes in the figures “Location of the temperature
sensors inside a lower cooling unit NTHR51AA” (page 548) and “Location
of the temperature sensors inside a lower cooling unit NTHR51AB”
(page 550). Avoid dropping the parts.
To see what your hand is doing, look through the spinning blades of the
adjacent fan. You may need a flashlight to increase visibility. The plug-in
of the right sensor is hidden behind a cluster of wires which cannot be
moved. Find the plug-in by touch.
2 Fasten the sensor and circuit board using the 2 M6 Phillips screws from
the removal. Tighten the screws to snug plus a 1/5 turn. If you drop a
screw, you must retrieve it to prevent equipment damage.
3 Remove the ESD mat.
4 Plug the unplugged red cable connector into the new sensor assembly as
shown in the figures “Cable connections inside a cooling unit NTHR51AA
or NTHR52AA” (page 549) and “Location of the temperature sensors
inside a lower cooling unit NTHR51AB” (page 550).
5 Re-install the fan controller according to the procedure “Installing a fan
controller” (page 452).
6 Re-install the fan according to the procedure “Installing a fan” (page 446).
7 Verify the operation of the replaced sensor by waiting
• for the fan LED to change from lit red to lit green
• a few minutes to hear the fans reduce rpm