Troubleshooting Chart For Gsm850 Receiver - Nokia NPM-10 Series Troubleshooting Instructions

CCS Technical Documentation

Troubleshooting Chart for GSM850 Receiver

1
Apply -55 dBm
881.6 MHz,
1
offset 67.71 kHz
from generator to
antenna connector
YES
Oscilloscope at
RX I/Q signal
704 mVpp
2
DC offset 1.38 V
freq. 67.64 kHz
YES
GSM chain
3
functional
4
5
6
By measuring with an oscilloscope at RXIP or RXQP on a working GSM850 receiver, the
following picture should be seen.
Signal amplitude peak-peak 704 mV
DC offset 1.38 V
Issue 1 03/2003
2
NO
Check Antenna
switch
at RX 850 Z700
-56 dBm
YES
Spectrum analyzer
GSM SAW filter
Z602
output -59 dBm
YES
Spectrum analyzer
Check signal after
inductors L603 and
L602
-59 dBm
YES
Oscilloscope
VRX 2.7 V
check Mjoelner
serial interface
Figure 8: GSM850 receiver troubleshooting chart
Nokia Corporation
Troubleshooting Instructions RF
3
NO Oscilloscope
check VANT1 and
VANT2 at Z700
signal 0V
YES
Check
Antenna switch
NO
Check SAW filter
Z602
NO
Check inductors
L603, L602
NO
Check Base band
Confidential
NPM-10
4
NO
Check Mjoelner
YES
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