Fault Finding Chart For Gsm900 Receiver - Nokia NHM-8NX Series Troubleshooting Instructions

NHM-8NX
Troubleshooting Instructions

Fault Finding Chart for GSM900 Receiver

1
Apply -55 dBm
942.4 MHz, offset
1
67.71 kHz
from generator to
antenna connector
YES
Oscilloscope at RX
I/Q
2 signal 588 mVpp
DC offset 1.35 V
freq. 67.71 kHz
YES
EGSM 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
Page 26
Figure 8: EGSM Receiver fault finding chart
2
NO
NO
Check RX/TX
switch at RX 900
Z700
-56 dBm
YES
Spectrum analyzer
NO
EGSM SAW filter
Z602
output -65 dBm
YES
Spectrum analyzer
NO
Check signal after
inductors L603 and
L602
-65 dBm
YES
Oscilloscope
NO
VRX 2.7 V
check Mjoelner
serial interface
ãNokia Corporation
PAMS Technical Documentation
3
NO
Oscilloscop
check Vc1 and Vc2 Check Mjoelner
at Z700 signal 0V
YES
Check RX/TX
switch
Check SAW filter
Z602
Check inductors
L603, L602
Check Base band
4
YES
Issue 1 05/02