User Guide

NHL-12
Nokia Customer Care 7 - RF Description & Troubleshooting
16 COMPANY CONFIDENTIAL Issue 2 10/2004
Copyright © 2004 Nokia. All Rights Reserved.
■ Troubleshooting charts for receiver
Troubleshooting diagram for GSM850 receiver
Phone in “Continuous” mode, AGC setting “12”.
No
No
Yes
Yes
NoNo
Yes
No
Yes
NoYes
Yes
Yes
Apply –90dBm
881.66771MHz signal
from generator to anten-
na connector
Oscilloscope at RX_I
Signal 700mVpp
DC offset 1.35V***
Frequency 67.7kHz
No
Change ge-
nerator level
to –50dBm
Spectrum analyzer
Antenna switch
outputs, GSM850
–88 dBm
Spectrum analyzer
Antenna switch
input
–84 dBm
Oscilloscope
VR1 4.8V and VR3..6 2.8V
Check HELGO serial
interface
(burst mode)
Synthesizer trou-
bleshooting
Spectrum analyzer
4G VCO out
3526.4MHz
∼–30 dBm (*
Oscilloscope
VANT_1...3 0V
Oscilloscope:
Check HELGO
serial interface
(burst mode)
Check HELGO
N7300
Check Base-
band
* Spectrum analyzer
reading with 1 kohm
passive probe (right val-
ue add +34 dB)
All spectrum analyzer reading
values are measured with
2.5 kohm passive probe (use
tweezers to connect the
probe ground to the nearest
PWB ground). Reading value
is represented without
+34 dB compensation.
850RX chain
functional
Check X7100,
C7103
Check Antenna
switch
Z7100
Spectrum analyzer
HELGO inputs
GSM850
–89 dBm
Check L7100,
L7101, Z7101
Check Base-
band
No
Yes
Yes
Check HELGO
N7300
* ** DC–level of RXI/RXQ in
continuous mode will decrease
slowly.
The original level can be resto-
red by rewriting gain set.