Ericsson LBI-39128 manual Troubleshooting, Symptom Possible Causes Corrective Action

LBI-39128 MAINTENANCE

transmitter channels. Repeat steps 2 through 6 for each transmitter channel until all are re-configured.

TROUBLESHOOTING

After you think you have fixed a transmitter alarm problem, switch the transmitter off (12V power supply), then

back on. This will cause the next test call to be placed to that transmitter and thereby speed up the check-out process and the transmitter’s return to service.

Table 10 lists some of the possible causes and the corresponding corrective action for various symptoms that might be observed.

Table 10 - Troubleshooting Symptoms

SYMPTOM	POSSIBLE CAUSE(S)	CORRECTIVE ACTION
Constant antenna alarm for one antenna,	Lower (power) Alarm Limit is set too	Check and possibly re-configure the
but antenna appears to be OK.	high, Upper (power) Alarm Limit is set	alarm limit(s) (see the Parameters
	too low, or Upper (SWR) Alarm Limit	heading in the Operation section).
	is set too low.
	Power sensor at antenna input needs	Check and possibly re-calibrate the
	calibration or is defective.	power sensor (see the Power Sensor
		Calibration heading in this section).
	Cable from the power sensor to the	Check the continuity of the cable from
	PMU (can be many cables and	the power sensor to the PMU (see the
	connectors in series) is connected to the	interconnection diagrams at the end of
	wrong point or is defective.	this manual).
	PMU input circuit is defective.	Apply a dc voltage (negative ground) to
		the power sensor end of the cable to the
		PMU (see Table 7 for the voltage to
		represent the expected power). If the
		alarm remains, the cable or the PMU
		input is defective.
Occasional antenna alarm for one	Power sensor at antenna input needs	Check and possibly re-calibrate the
antenna, but antenna appears to be OK.	calibration or is defective.	power sensor (see the Power Sensor
		Calibration heading in this section).
No antenna alarm is reported when the	Lower Alarm Limit is set to zero.	Re-configure the Lower Alarm Limit
cables between the power sensor and		parameter for the antenna to some non-
the PMU are disconnected.		zero value (see the Parameters heading
		in the Operation section).
	(Continued)

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