Nortel Passport 15000, Установка и обслуживание оборудования, Страница: 542 / 874

542 Chapter 17 Hardware procedures
241-1501-240 5.2S2
Installing a temperature sensor for an upper cooling unit
Install an upper cooling unit temperature sensor to restore optimum cooling
and to reduce the rpm of the fans to normal speed.
Prerequisites
• You must be familiar with “Safety considerations and best practices”
(page 53).
• You need the appropriate version of temperature sensor:
— NTCC8938 (or A0647397) for the temperature sensor in the bracket
assembly NTHR68AA used with an upper (front) cooling unit
NTHR52AA; all sensors on a bracket assembly must have the same
part number
— A0521944 or NTCC8938 (or A0647397) for the temperature sensor
in the bracket assembly NTHR68AB used with an upper (front)
cooling unit NTHR52AB
• You need a very short-shafted screwdriver for a small Phillips screw and
a step ladder to see onto the top of an upper shelf in a NEBS 2000 frame
or other mounting apparatus.
Procedure steps
1 At the rear top of the upper shelf, align the replacement temperature
sensor and circuit board with the 2 screw holes. Refer to the figure
“Location of the temperature sensors on a bracket assembly” (page 543).
Avoid dropping the sensor assembly.
2 Fasten the sensor assembly 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. See the orientation of
the sensors in the figures:
• “A temperature sensor on the bracket assembly NTHR68AA for a
cooling unit NTHR52AA” (page 544)
• “A temperature sensor on the bracket assembly NTHR68AB for a
cooling unit NTHR52AB” (page 545)
3 Plug the unplugged cable connector into the new sensor assembly. Apply
gentle, even, steady, and straight force.
4 Verify the operation of the replaced sensor by waiting: