Nokia 2650 Service Manual page 196

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Figure 29:Troubleshooting chart for GSM850 receiver
Apply -55dBm
881.6MHz
(ch 190)
Offset 67.71kHz
from generator to X700
Osciloscope at
RX I/Q.
Signal 580mVpp
DC offset 1.35V
Freq. 67.71kHz
No
Spectrum analyser
RX level (FEM, N700) at
RX900/850 point
-56 dBm
Yes
Spectrum analyser
SAW filter Z602 output
-65dBm
Yes
Spectrum analyser
Check signal after inductors
L602 and L603
-65dBm
Yes
Osciloscope
VRX 2.78 Vdc (C225)
Check Mjoelner serial
interface
Issue 2 06/2005
Yes GSM850 OK
Osciloscope
check VC1, VC2, Vtx and
No
BS, according to logic table
at N700
Yes
No Check Z602
Check inductor
No
L602, L603
No Check UEM, UPP
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Check Mjoelner
No
N600
Check FEM
N700
Yes
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