Nem-4 Synthesizer; General Instructions For Synthesizer Troubleshooting - Nokia NEM-4 Series Troubleshooting Instructions

NEM-4
RF Troubleshooting
from DET to compare with TXC. The result is that Mjoelner drives VDP_900/VPD_1800
high to try and increase the power output so that the DET signal is matching TXC. With a
break in the Power Control loop, the DET signal never reaches Mjoelner so it assumes
that the PA is not outputting enough power so it tries to compensate by increasing the
gain.
When checking the Power Control loop, make sure that (C803) is pulsing at 2.8V Peak to
Peak. Check the DET pulse at Mjoelner input on R706.
This case is the same for EGSM, DCS1800 & DCS1900.
Are R706, R707
NO
& R708 OK?
Replace Faulty
Components

NEM-4 Synthesizer

There is only one PLL synthesizer generating frequencies for both Rx and Tx for all three
bands (EGSM900, GSM1800 and GSM1900). VCO frequency is divided by 2 or by 4 in
Mjoelner depending on which band is active.

General instructions for Synthesizer Troubleshooting

Connect the phone to a PC with DAU-9P cable and dongle and follow these instructions:
Start Phoenix Service Software (dongle needed):
Open FBUS connection
Page 6(b)-86
Company Confidential
Is DET Pulse
YES
on C805 OK?
YES
Eunsure that VBD
is pulsing 2.8V
Pk - PK and
investigate Mjoelner
KEY
Test With
Test With
Spectrum
Oscilloscope
Analyzer
Copyright  2003 Nokia Corporation.
Company Confidential
CCS Technical Documentation
NO
Is RF Signal
at V801 OK?
Is DET Pulse
Replace
NO
on C804 OK?
V801
Check / End
Inspect Action
NO
Replace
L801
YES
Replace
YES
R802
Issue 1 09/2003