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Pre–Power–up Tests – continued

July 1999

2-15

SC 4812ET BTS Optimization/ATP – CDMA LMF

PRELIMINARY 2

DC Power Pre-test (BTS Frame)

Before applying any power to the BTS cabinet, follow the steps outlined

in Table 2-18 while referring to Figure 2-2 to verify there are no shorts in

the RF or Power Cabinet’s DC distribution system.

Table 2-18: DC Power Pre–test (RF Cabinet and Power Cabinet)

Step Action

1 Physically verify that all DC/DC converters supplying power to the cabinets are OFF or disabled.

2 On each RF cabinet:

 Unseat all circuit boards/ modules in the distribution shelf, transceiver shelf, and Single Carrier

Linear Power Amplifier (SCLPA) shelves, but leave them in their associated slots.

 Unseat all circuit boards (except CCD and CIO cards) in the C–CCP shelf and LPA shelves, but

leave them in their associated slots.

 Set C–CCP shelf breakers to the OFF position by pulling out power distribution breakers (labeled

C–CCP 1, 2, 3 – located on the power distribution panel).

 Set LPA breakers to the OFF position by pulling out power distribution breakers (8 breakers,

labeled 1A–1B through 4C–4D – located on the power distribution panel).

– 1A through 3B – ELPA breakers (earlier model breaker panel – use breakers 1 through 24)

3 Verify that the resistance from the power (+ or –) feed terminals with respect to the ground terminal on

the cabinet measures >

500 Ω.

 If reading is < 500 Ω, a short may exist somewhere in the DC distribution path supplied by the

breaker. Isolate the problem before proceeding. A reading > 3 M

Ω could indicate an open (or

missing) bleeder resistor (installed across the filter capacitors behind the breaker panel).

4 Set the C–CCP breakers (C–CCP 1, 2, 3) to the ON position by pushing them IN one at a time.

Repeat step 3 after turning on each breaker.

* IMPORTANT

If, after inserting any board/module, the ohmmeter stays at 0 Ω, a short probably exists in that

board/module. Replace the suspect board/module and repeat the test. If test still fails, isolate the

problem before proceeding.

5 Insert and lock the DC/DC converter modules into their associated slots one at a time. Repeat step 3

after inserting each module.

 A typical response is that the ohmmeter will steadily climb in resistance as capacitors charge, finally

indicating approximately 500

Ω.

! CAUTION

Verify the correct power/converter modules by observing the locking/retracting tabs appear as follows:

–

(in +27 volt systems)

6 Insert and lock all remaining circuit boards and modules into their associated slots in the C–CCP shelf.

Repeat step 3 after inserting and locking each board or module.

 A typical response is that the ohmmeter will steadily climb in resistance as capacitors charge,

stopping at approximately 500

Ω..

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