User Guide

PAMS
Technical Documentation
RAE-3
8. Troubleshooting
Page 8 – 120
Issue 1 06/01
5.3.2 Troubleshooting diagram for EGSM Transmitter
EGSM TX troubleshooting
Check with oscilloscope :
R742 power > 0dBm, 897,6 MHz ?
YES
R565:: VREF Vdc = 1.5V ?
NO
YES
R700 & R740 VTX Vdc = 2.7 V?
TPJ320 TXP Vdc>2.5 V ?
C557 VRX Vdc = 2.7 V ?
C561 VSYN_2 Vdc = 2.7 V ?
C550 VXO Vdc = 2.7 V ?
Check
Baseband
NO
Check with oscilloscope :
R546 & C640 TXQ_0 Vac= 0.4Vpp, Vdc=0.8V
R546 & C640 TXQ_180 Vac=0.4Vpp, Vdc=0.8V
R541 & C541 TXI_0 Vac=0.4Vpp, Vdc=0.8V
R541 & C541 TXI_180 Vac=0.4Vpp, Vdc=0.8V
Check
Baseband
NO
YES
Check with oscilloscope :
R755 TXBUFF Vdc > 2.0 V
C789 TXVGSM Vdc > 2.0 V
C798 TXVPCN Vdc < 0.3 V
C731 TXVDET Vdc > 2.0 V
Check
Hagar serial interface
Hagar
Spectrum analyzer:
NO Check
Hagar
YES
R751 power >–5 dBm, 902 MHz ?
Spectrum analyzer:
NO Check
EGSM SAW
YES
Synthesizer
filter
Z671 power >–7 dBm, 902 MHz ?
Spectrum analyzer:
NO Check
Diplex
YES
filter Z671
YES
(cont. next page)
Figure 124.