User Guide

PAMS Technical Documentation Disassembly and Troubleshooting
TME-3
Issue 3 10/03 Nokia Corporation. Page 23
Figure 19: Troubleshooting diagram for GSM1800 receiver
Troubleshooting diagram for GSM1800 receiver
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
reading with 1 kohm
passive probe (right
value add +26 dB)
Yes
No
Check dual RX
SAW Z520
Check
Antenna
switch
Z500
Spectrumanalyzer
1800_RX
-78 dBm
No
Yes
No
Check
Baseband
Check Hagar
N600
No
Oscilloscope
VR4 2.7V
Check Hagar
serial interface
(burst mode)
Check V550,
R551, L550,
R558
No
Yes
Check V550,
C551, L552
Oscilloscope
V550, RFout 2.6V
V550, RFin 0.8 V
No
Check C552
Yes
Spectrumanalyzer
V550, RFout
–58 dBm
Yes
Yes
Oscilloscope
LNA_P 0V
LNAB_P 2.7V
Yes
Yes
Check Hagar
N600
No
Synthesizer
troubleshooting
Spectrumanalyzer
4G VCO out
3685.6MHz
~-30 dBm (*
Yes
No
Check Baseband
Check Z551,
C555, C556, L551
No
Yes
Oscilloscope
VR4 2.7V
Check Hagar
serial interface
(burst mode)
Spectrumanalyzer
1800 bal out
-66 dBm
Yes
GSM1800 RX chain
functional
Spectrumanalyzer
1800 1st SAW out
-77 dBm
No Yes
Spectrumanalyzer
1800 LNA out
-61 dBm
Change
generator
level to
–50dBm
No
Oscilloscope at RX_I
Signal 700mVpp
DC offset 1.35V
Frequency 67.7kHz
Apply –90dBm
1842.86771MHz
signal from generator
to antenna connector
Yes