RM-12
CCS Technical Documentation
Issue 1 11/2004
COMPANY CONFIDENTIAL
25
Copyright © 2004 Nokia. All Rights Reserved.
Troubleshooting diagram for GSM900 receiver
Phone in “Continuous” mode, AGC setting “12”..
Figure 4: GSM900 receiver troubleshooting
Apply –90dBm
942.46771MHz signal
from generator to
antenna connector
Osilloscope at RX_I
signal 170mVpp DC
offset 1.35***
Frequency 67.7kHz
Note! Generator level can be set higher if
needed. Just note that levels will be different
in whole chain respectively.
Spectrumanalyzer:
Antenna Switch
output GSM900
–88dBm
Spectrumanalyzer:
Antenna Switch
input –88dBm
Spectrumanalyzer:
HELGO inputs
GSM900 –89dBm
Oscilloscope
VANT_1…3 0V
Oscilloscope:Check
HELGO serial
interface (burst
mode)
Oscilloscope:
VR1,3…6 2.7V
Check HELGO
serial interface
(burst mode)
* Spectrumanalyzer reading
with 1 kohm passive probe
(right value add +26dB)
All spectrumanalyzer
reading values are
measured with 1 kohm
passive probe (use
tweezers to connect the
probe ground to the nearest
PWB ground). Reading
value is represented without
+26 dB compensation.
Spectrumanalyzer:
4G VCO output
3769.6MHz
~-30dBm*
Check HELGO
N500
Check
Baseband
Check
C809
Rx 900 chain
functional
Check
L809,L810
Check
Baseband
Synthesizer
troubleshooting
Check HELGO
N500
Check Antenna
Switch Z800
*** DC-level of RXI/RXQ in
continuous mode will
decrase slowly. The original
level can be restored by
rewriting gain set
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
No
No
No
No
No
No
No
No
Check SAW
filter output
Check SAW
Z809
Yes
No
X7100
L7104, L7103
Z7101
Z7100
N7300
N7300