User Guide

CCS Technical Documentation
Company confidential RH-23
Issue 1 03/2004 Nokia Corporation. Page 29
Figure 22: Synthesizer troubleshooting diagram
From Phoenix choose:
File -> Choose product -> RH 23/33
Maintenance -> Testing -> RF controls
-> GSM900/1800/1900 -> RX ->
continuous -> ch 37/700/661
Check with spectrum analyzer VCO
frequency:
3769.6 MHz (GSM900)
3685.6 MHz (GSM1800)
3920 MHz (GSM1900)
Level > -10 dBm*
*When 2.5 kOhm passive probe is
used, correct the measurement by
+34 dB.
Synthesizer OK
Yes
Yes
Check with oscilloscope VCTCXO
(G501) power supply 2.7 V
No
No
Baseband
troubleshooting
Check with oscilloscope VCTCXO
(G501) output 26 MHz approx. 800
mVp-p
Replace VCTCXO
(G501)
Yes
No
Check with oscilloscope VCO power
supply R500 2.7 V
Yes
Baseband
troubleshooting
No
Check with spectrum analyzer VCO
output: some signal between 3 and 4
GHz
Replace VCO (G500)
Yes
No
Yes
Check with
oscilloscope VCO
control voltage
between 0.5 and 4
V
Check loopfilter
R501-2, C503-5
No
Replace Helgo
(N500)