User's Manual

Basic Troubleshooting: RF Path Fault Isolation68P64115A18–1

Mar 2003

1X SC 4812T Lite BTS Optimization/ATP Software Release R2.16.1.x

DRAFT

6-13

Single–Sided BLO Checkbox

When performing a calibration with the TX Calibration... or All

Cal/Audit... functions, the Single–Sided BLO checkbox should not be

checked when the redundant BBX is being calibrated. When a

calibration fails with the redundant BBX selected, try re–running the

calibration with the Single–Sided BLO checkbox unchecked. If the

calibration still fails, refer to the following paragraphs and use the TX

output fault isolation flowchart to identify the most probable cause of the

failure.

If Faults Are Isolated

If the fault reports are isolated between successful path checks, the root

cause of the faults most likely lies with one or more of the Field

Replaceable Unit (FRU) modules. If more than one failure was reported,

look for a common denominator in the data. For example, if any TX test

fails on one sector only, the BBX assigned to that sector (Table 1-6) is a

likely cause. Also, look at the severity of the failure. If the path loss is

just marginally out of the relaxed specification limit during the

post-calibration TX audit, suspect excessive cable loss. If limits are

missed by a wide margin, suspect mis–wired cables or total device

failure. Use the TX output fault isolation flowchart in Figure 6-1 to

identify the strongest possible cause for a failed TX test.

Fault Isolation Flowchart

The flowchart covers the transmit path. Transmit paths usually fail the

lower test limit, indicating excessive loss in some component in the BTS

site or mis–wiring. A failure of an upper limit usually indicates a

problem with the test setup or external equipment. Before replacing a

suspected FRU, always repeat and verify the test results to rule out a

transient condition. If a BBX fails an upper limit in the post–calibration

audit procedure, re–calibrate and verify the out–of–tolerance condition

for that BBX and/or sector before replacement.

Flowchart Prerequisites

Before entering the fault isolation sequence outlined in the flowchart, be

sure the following have been completed:

S GLIs, MCCs, and BBXs have been downloaded with the correct ROM

code, RAM code, and data (Table 3-12, Table 3-13, and Table 3-14).

S MGLI, CSMs, and MCCs are enabled (Table 3-13, Table 3-16, and

Table 3-17, respectively)

S Be sure the LED on the correct CCD card is solid green.

S Be sure no alarms are being reported by opening an LMF alarm

window as outlined in Table 3-47.