User Guide

TME-3
Disassembly and Troubleshooting PAMS Technical Documentation
Page 22 Nokia Corporation. Issue 3 10/03
Figure 18: Troubleshooting diagram for GSM900 receiver
Troubleshooting diagram for GSM900 receiver
Apply –90dBm
942.46771MHz
signal from generator
to antenna connector
Yes No Yes No No No
Oscilloscope at RX_I
Signal 700mVpp
DC offset 1.35V
Frequency 67.7kHz
Change
generator
level to
–50dBm
Spectrumanalyzer
900 LNA out
-61 dBm
Spectrumanalyzer
900 1st SAW out
-80 dBm
Spectrumanalyzer
900_RX
-79 dBm
Check
Antenna
switch
Z500
Yes Yes
EGSM RX chain
functional
Check dual RX
SAW Z520
Yes
No No
Oscilloscope
LNA_G 2.7V
LNAB_G 2.7V
Oscilloscope
VR4 2.7V
Check Hagar
serial interface
Check R501
Check
Baseband
Yes
Yes
Check Hagar
N600
Yes
Yes
Spectrumanalyzer
V500, RFout
–57 dBm
Check C502
No No
Oscilloscope
V500, RFout 2.7V
V500, RFin 0.8 V
Check V500,
L500, R502
Yes
Check V500,
C501, L502, L503
No
Spectrumanalyzer
900 bal out
-66 dBm
Check Z501,
C505, C506, L501
Yes No
Oscilloscope
VR4 2.7V
Check Hagar
serial interface
(burst mode)
Check Baseband
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.
Yes No
Spectrumanalyzer
4G VCO out
3769.6MHz
~-30 dBm (*
Synthesizer
troubleshooting
Yes
* Spectrumanalyzer
reading with 1 kohm
passive probe (right
value add +26 dB)
Check Hagar
N600