Nokia 2650 - Page 205

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Nokia Customer Care
48 COMPA2005NY CONFIDENTIAL Issue 2 06/2005
Copyright © 2005 Nokia. All Rights Reserved.
Figure 38:Troubleshooting chart for GSM1800 receiver
Osciloscope at
RX I/Q.
Signal 580mVpp
DC offset 1.35V
Freq. 67.71kHz
Apply -55dBm
1842.8MHz
(ch 700)
Offset 67.71kHz
from generator to X700
GSM1800 OK
Spectrum analyser
RX level (FEM, N700) at
RX1800/1900 point
-56 dBm
Osciloscope
check VC1, VC2, Vtx and
BS, according to logic table
at N700
Check Mjoelner
N600
Spectrum analyser
SAW filter Z601 output
-65dBm
Check Z601
Spectrum analyser
Check signal after inductors
L610 and L612
-65dBm
Osciloscope
VRX 2.78 Vdc (C225)
Check Mjoelner serial
interface
Check inductor
L610, L612
Check UEM, UPP
Yes
No
No
Yes
No
No
Yes
No
No
Yes
Yes
Check FEM
N700
Yes