Fault Finding Chart For Pll Synthesizer - Nokia RH-6 Series Rf Description & Troubleshooting

CCS Technical Documentation
It is possible to measure the tuning voltage at the Vc input of the VCO (C712) easily. For
= 3769.6MHz the tuning voltage should be 2.3V
f
VCO
VCO is 240MHz/V typ.).
If this is not the case, please refer to section "Fault finding chart for PLL Synthesizer"
below.

Fault finding chart for PLL synthesizer

Setup with
Band: GSM 900
Mode: RX Continuous
Channel: 37
Spectrumanalyzer
VCO out (G701) No
f = 3769.6 MHz
VCO
U =2.3..2.8V
tune
Yes
Oscilloscope
Bluetooth Clockbuffer
No
(R601 LPRFCLK_I)
26MHz app. 0.6Vpp
Yes
PLL Block is functional
It is important to note that the power supply of the VCXO (VR3) is only switched off in
the so-called 'Deep Sleep Mode' and the power supply of the VCO (G701 VR7) is switched
off in so-called 'Sleep Mode'.
Issue 1 10/2003
Company Confidential
BB not working
PLL Synthesiser Fault finding Tree
because 26MHz
missing.
Oscilloscope
VCXO Supply (C607)
Yes
(
VR3=2.78V, VIO=1.8V
VREF1=1.35V)
No
Check supply filter components
Check BB, and Software
Phone not in function
Check Bluetooth
Clockbuffer
R601,R602,R603,
V601,C602
(For a failure free working of BB the 26MHz clock is necessary!!!)
If the 26MHz clock isn´t work please check first the necessary voltages
VR3;VIO and VREF01. This can be checked after power on for a time of
about 32sec. After that time the voltages a going down.)
Figure 11: PLL Synthesizer Fault Finding Chart
Copyright © 2003 Nokia Corporation.
Company Confidential
7 - RF Description & Troubleshooting
.. 2.8V
DC
Oscilloscope
VCXO output
Yes
(R425 RFCLK
26MHz,app.0.8Vpp
No
check R618; C425
B601+Mjoelner
Loop filter components?
If ok change Mjoelner
Yes
Wrong writing on RFBus
(see BB part)
RH-6
(Tuning sensitivity of
DC
Oscilloscope VCO supply
(
VR7 = 2.78V, VR5=2.78V)
VR1A=4.7V
No
Check supply filter components
Check UEM, and Software
Phone not in function
Spectrumanalyzer
VCO out (G701 out)
Some signal 3-4 GHz
No
Change VCO G701
Page 31
Yes