User Guide

CCS Technical Documentation
Company confidential RH-20
Issue 1 10/2003 Nokia Corporation. Page 29
Troubleshooting diagram for GSM1900 receiver
Phone in “Continuous” mode, AGC setting “12
Figure 23: GSM1900 receiver troubleshooting
A
pply –90dBm
1960.06771MHz signal
from generator to
antenna connector
Osilloscope at RX_I
signal 160mVpp DC
offset 1.35***
Fre
q
uenc
y
67.7kHz
Note! Generator level can be set higher
if needed. Just note that levels will be
different in whole chain respectively.
Spectrumanalyzer:
A
ntenna Switch
outputs, GSM1900
SAW in
p
ut -88dBm
Spectrumanalyzer:
A
ntenna Switch
input –84dBm
Spectrumanalyzer:
HELGO inputs
GSM1900 –88dBm
Oscilloscope:
VANT_3 2.7V
VANT_1/2 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)
A
ll 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
3920 MHz
~-30dBm*
Check HELGO
N500
Check
Baseband
Check
C809
Rx 1900 chain
functional
Check Z806
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
Y
es
Yes
Yes
Yes
Yes
No
No
No
No
No
No
No
No
Spectrumanalyzer:
RX_SAW_out –
90dBm (C826)
Oscilloscope:
LNA_VCC 2.6
LNA_P 0V
Check Baseband
Oscilloscope:
Check R800,
R810, L800
VR1,3…6 2.7V
Check HELGO
serial interface
(burst mode)
Check
HELGO N500
Check C808,
L805, C807
Yes
Yes
No
No
No
Check LNA
output from C829
–84dBm
Check Balun
T701 output
C808, C807
Check
Balun
Yes
Yes
No
No
Yes