User Guide

PAMS
Technical Documentation
RAE-3
8. Troubleshooting
Page 8 – 123
Issue 1 06/01
5.4.2 Troubleshooting diagram for PCN Transmitter
PCN TX Troubleshooting
Check with oscilloscope :
R741 power >0dBm, 1747,6 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 < 0.3 V
C790 TXVPCN Vdc > 2.0 V
C731 TXVDET Vdc > 2.0 V
Check
Hagar serial interface
Hagar
Spectrum analyzer:
NO Check
Hagar
YES
Z741 (pin 3)
Spectrum analyzer: NO Check
YES
Synthesizer
filter Z671
PA N702, pin 8
Spectrum analyzer: NO Check
V801 PA buffer
YES
R753 3dB att.
YES
(cont. next page)
power > +6 dBm, 1747,6 MHz
Diplex
power > +3 dBm, 1747,6 MHz
Figure 127.