Troubleshooting Diagram For Egsm900 Receiver - Nokia NPM-6 Series Troubleshooting Instructions

NPM-6/6X
Troubleshooting Instructions

Troubleshooting diagram for EGSM900 receiver

Phone in "Continuous" mode, AGC setting "12"
Apply –90dBm
942.46771MHz signal
from generator to anten-
na connector
Yes No
Oscilloscope at RX_I
Signal 700mVpp
DC offset 1.35V***
Frequency 67.7kHz
Yes
900RX chain
functional
Page 18
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Figure 11: EGSM900 receiver troubleshooting
Yes
Spectrumanalyzer
Change ge- Spectrumanalyzer
Antenna Switch
Antenna Switch
nerator level
outputs,EGSM900 outputs, GSM900
to –50dBm
–88 dBm
-88dBm
Yes
Spectrumanalyzer
HELGA inputs
EGSM900 -89dBm
GSM900
–89 dBm
Yes
Oscilloscope
VR1,3...6 2.7V
Check HELGA serial
interface
(burst mode)
Spectrumanalyzer
4G VCO out
3769.6MHz
∼–30 dBm (*
Yes
Check HELGA
N500
Copyright Nokia. All rights reserved.
CCS Technical Documentation
No No
Spectrumanalyzer
Antenna Switch
input
–84 dBm
Yes
No
Oscilloscope Oscilloscope :
Check HELGA
VANT_1...3 0V
serial interface
(burst mode)
Yes
Check HELGA
N500
Check Antenna
All spectrumanalyzer reading
switch
values are measured with
Z800
2.5 kohm passive probe (use
tweezers to connect the
probe ground to the nearest
PWB ground). Reading value
No
is represented without
Check L809
+34 dB compensation.
L810
* Spectrumanalyzer
No
reading with 1 kohm
Check Base-
band passive probe (right val-
ue add +34 dB)
No
Synthesiszer trou-
bleshooting
Check C831,
L811
No
Check Base-
band
Yes
* ** DC–level of RXI/RXQ in
continuous mode will decrease
slowly.
The original level can be resto-
red by rewriting gain set.
Issue 2 06/03