User Guide

CCS Technical Documentation Troubleshooting — RF
RH-17
Issue 1 04/2003 Nokia Corporation Confidential Page 47
Table 6: VCTCXO Troubleshooting
Table 7: AFC PDM (Local Mode) AMPS
VCTCXO G501
at 19.2 MHz
TP30 AFC_Volt
PDM
[0]=2.2V
[-1024]=1.4
[+1023]=3.1
Check supply voltage VR3 at G501 is at
2.7 Vdc, verify C520, R512 and C505.
Control voltage AFC should be ~ 1.27
Vdc, check R511, R510, C503 make sure
VR1A is present at 4.75 Vdc.
Check AFC PDM control in local mode
using Table 7 as a reference.
CLK19M2_R TP29 19.2 MHz at
amplitude of
-24.0 dBm
Check C513
CLK19M2_B TP32 19.2 MHz at
amplitude of
-24.0 dBm
Check C512
CLK19M2_UPP TP31 19.2 MHz at
amplitude of
-21.0 dBm
Check Buffer Amplifier V500 for correct
dc bias voltages via VR3.
Emitter = 0.38 Vdc
Base = 1.04 Vdc
Collector = 1.75 Vdc
Check components V500, C502, R520,
R521, R522, R517, R518, C523, C525
and C524.
AMPS Mode
PDM AFC Frequency Output Frequency Output
Setting Voltage @ G501 using @ G501 using
Oscilloscope Spectrum Analyzer
-1024 1370 mV 19.19 MHz 19.199515 MHz
-512 1780 mV 19.21 MHz 19.199735 MHz
0 2.2 V 19.23 MHz 19.199965 MHz
+512 2.65 V 19.23 MHz 19.200000 MHz
+1023 3.1 V 19.23 MHz 19.200220 MHz