Nokia RM-57, Руководство по обслуживанию

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Nokia Customer Care Appendix A: RF Troubleshooting
Company Confidential
Copyright © 2005 Nokia. All rights reserved
A-49
• Note! EGSM_RX and EGSM_TX voltages are the same for GSM850.
3.2.1.1.1.1 Replace Hinku (N7500)
3.2.1.1.2 Replace antenna switch Z7503
3.2.1.2 Are matching components in place and working correctly?
GSM850/EGSM900: C7512, C7514 and L7504
GSM1800: C7581, C7584 and L7505
GSM1900: C7523, C7525 and L7506
• Check that components are in place and solder joints are ok
• Use an ohmmeter to check that inductors are conducting DC.
• Replace matching components
3.2.2 Are RX-IQ signal waveforms and levels correct?
•
Measurements can be done with an oscilloscope, a probe and signal generator.
• GSM receiver has to be active before RX IQ-signals can be measured. Procedure is explained in
section “GSM RX chain activation for manual measurements”.
• Apply –70 dBm RF signal from a signal generator to the module jig antenna connector and
use following frequencies:
-
EGSM900: 942.46771 MHz (Channel 37)
-
GSM1800: 1842.86771 MHz (Channel 700)
-
GSM1900: 1960.06771 MHz (Channel 661)
• Remember to change correct RX channels also to Phoenix “RF controls” window!
• Check RX I and RX Q -signals in following test points:
-
RX I (positive): Connect the probe to test point J7508
-
RX I (negative): Connect the probe to test point J7509
-
RX Q (positive): Connect the probe to test point J7510