User Guide

RM-94
Nokia Customer Care 6(b) - RF Troubleshooting
34 COMPANY CONFIDENTIAL Issue 1 04/2005
Copyright © 2005 Nokia. All Rights Reserved.
■ Fault finding chart for PLL synthesizer
Figure 4:PLL Fault Finding Tree
Yes
Check Baseband part for errors
Phoenix:
Phone is responding to Phoenix commands. For example,
Ctrl-R reads the right phone information.
No
Synthesizer
Fault Finding Tree
part 1
Baseband part is not working,
possible reason: 26MHz missing.
Oscilloscope:
Check VCTCXO supply
(VR3=2.78V, this can be checked after
power on for a time of about
32sec
.
A
fter that time the voltage is going
down.)
Check supply filter components :
C2235, R7516, C7526.
Check UEM and base band part.
No
Oscilloscope
VCTCXO output at G7501
26MHz,app.0.8Vpp
VCTCXO G7501 defective or
short circuit to GND.
No
Yes
Oscilloscope
REFCLK output of N7500:
Signal VCTCXO=RFCLK_I
at C2902, R2902.
26MHz,app.0.8Vpp
No
Yes
Check supply filter components:
R7519, C7522, VDIG at N7500
Check C2902, R2902 and N7500.
Check UEM and Software.
Yes