Troubleshooting Diagram For Gsm1900 Receiver - Nokia NPM-6 Series Troubleshooting Instructions

Troubleshooting Instructions

Troubleshooting diagram for GSM1900 receiver

Phone in "Continuous" mode, AGC setting "12
Apply –90dBm
1842.86771MHz signal
from generator to anten-
na connector
Yes No
Oscilloscope at Change ge-
RX_I /RXQ
nerator level
Signal 160mVpp
to –50dBm
DC offset 1.35V ***
Frequency 67.7kHz
Yes
GSM1800 RX chain
functional
Spectrumanalyzer
HELGA inputs
GSM1900
–78 dBm
Oscilloscope
VR1,3...6 2.7V
Check HELGA serial
interface
(burst mode)
Yes
Spectrumanalyzer
4G VCO out
3685.6MHz
∼–30 dBm (*
Check HELGA
N500
Page 20
Figure 13: GSM1900 receiver troubleshooting
Yes No
Spectrumanalyzer
Antenna Switch out-
put, GSM1900
–88 dBm
Spectrumanalyzer
RX_SAW_out
Yes
–90 dBm
Oscilloscope
LNA_VCC 2.6V
LNA_P 0 V
Yes
Check V802,
Z806
C826, Z802,
C829, C8097,
C808
Check Baseband
Synthesiszer trou-
bleshooting
Yes
ãNokia Corporation.
CCS Technical Documentation
No
Spectrumanalyzer
Check C831,
Antenna Switch input
L811
–84 dBm
Yes
No
Oscilloscope Oscilloscope
VANT_3 2.7VV
Check HELGA se-
VANT_1/2 0V
rial interface (burst
mode)
Yes
Yes
Check Antenna
switch Z800
Check HELGA
N500
Check Baseband
Oscilloscope
VR1,3...6 2.7V
Check Baseband
Check HELGA serial
interface
(burst mode)
Yes
All spectrumanalyzer reading
Check HELGA
values are measured with 1
N500
kohm passive probe (use
tweezers to connect the
probe ground to the nearest
PWB ground). Reading value
is represented without +26
dB compensation.
* Spectrumanalyzer
reading with 1 kohm
passive probe (right val-
ue add +26 dB)
* ** DC–level of RXI/RXQ in
continuous mode will decrease
slowly.
The original level can be resto-
red by rewriting gain set.
No
Check Base-
band
Issue 1 01/03