Troubleshooting Diagram For Gsm1800 Receiver - Nokia NPM-6 Series Troubleshooting Instructions

CCS Technical Documentation

Troubleshooting diagram for GSM1800 receiver

Phone in "Continuous" mode, AGC setting "12
Apply –90dBm
1842.86771MHz signal
from generator to anten-
na connector
Yes No
Oscilloscope at RX_I Change ge-
Signal 140mVpp
nerator level
DC offset 1.35V ***
to –50dBm
Frequency 67.7kHz
Yes
GSM1800 RX chain
functional
Issue 1 01/03
Figure 12: GSM1800 receiver troubleshooting
Yes No
Spectrumanalyzer
Spectrumanalyzer
Antenna Swithc input
Antenna switch out-
-84 dBm
puts,
1800 LNA out
–61 dBm
Oscilloscope
VANT_1...3 0V
Yes
Check Antenna
Switch Z800
No
Spectrumanalyzer
HELGA inputs
GSM 1800
–88 dBm
Yes
Oscilloscope
No
VR1,3...6 2.7V
Check HELGA serial
interface
(burst mode)
Yes
Spectrumanalyzer
No
4G VCO out
3769.6MHz
∼–30 dBm (*
Yes
Check HELGA
N500
ãNokia Corporation.
Troubleshooting Instructions
No
Check C831,
L811
Yes
No No
Oscilloscope
Check HELGA se-
rial interface (burst
mode)
Yes
Yes
Check Helga
Check HELGA
N500
N500 N600
All spectrumanalyzer reading
values are measured with 1
kohm passive probe (use
tweezers to connect the
Check C838, C839,
probe ground to the nearest
L821. L 872,
PWB ground). Reading value
C836, C837,
is represented without +26
V801
dB compensation.
Check Base-
band
* Spectrumanalyzer
reading with 1 kohm
passive probe (right val-
ue add +26 dB)
Synthesiszer trou- * ** DC–level of RXI/RXQ in
bleshooting continuous mode will decrease
slowly.
The original level can be resto-
red by rewriting gain set.
Check Base-
band
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