Fault Finding Chart For Gsm1800 Receiver - Nokia NHM-8NX Series Troubleshooting Instructions

PAMS Technical Documentation

Fault Finding Chart for GSM1800 Receiver

1
Apply -55 dBm
1842.8 MHz, offset
1
67.71 kHz
from generator to
antenna connector
YES
Oscilloscope at RX
I/Q
signal 408 mVpp
2
DC offset 1.33 V
freq. 67.71 kHz
YES
PCN chain
3
functional
4
5
6
By measuring with an oscilloscope at RXIP or RXQP on a working GSM 900 receiver this
picture should be seen.
Signal amplitude peak-peak 588 mV
DC offset 1.33 V
Issue 1 05/02
Figure 10: GSM1800 receiver fault finding chart
2
NO
NO
Check RX/TX
switch at RX 1800
Z700
-57 dBm
YES
Spectrum analyzer
NO
PCN SAW filter
Z601
output -65 dBm
YES
Spectrum analyzer
NO
Check signal after
inductors L611 and
L601
-65 dBm
YES
Oscilloscope
NO
VRX 2.7 V
check Mjoelner
serial interface
ãNokia Corporation
Troubleshooting Instructions
3
NO
Oscilloscop
check Vc1 and Vc2 Check Mjoelner
at Z700 signal 0V
YES
Check RX/TX
switch
Check SAW filter
Z601
Check inductors
L611, L601
Check Base band
NHM-8NX
4
YES
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