Troubleshooting Diagram For Gsm1800 Receiver - Nokia NPL-3 Series Troubleshooting Instructions

NPL-3
Troubleshooting Instructions

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
Page 26
Company confidential
Figure 22: 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
No
Spectrumanalyzer
o
HELGA inputs
GSM 1800
–88 dBm
Yes
Oscilloscope
No
VR1,3...6 2.7V
o o o o
Check HELGA serial
interface
(burst mode)
Yes
Spectrumanalyzer
No
4G VCO out
3769.6MHz
∼–30 dBm (*
Yes
o
Check HELGA
N500
ãNokia Corporation.
CCS Technical Documentation
No
Check C831,
L811
Yes
No
Oscilloscope
o o
Check HELGA se-
rial interface (burst
mode)
Yes
Yes
Check HELGA
N600
Check Antenna
Switch Z800
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.
No
Check Base-
band
o o
Issue 1 3/03