User Guide

RM-94
Nokia Customer Care 6(b) - RF Troubleshooting
16 COMPANY CONFIDENTIAL Issue 1 04/2005
Copyright © 2005 Nokia. All Rights Reserved.
No
No
Check supply
filter components
around V7800
and RF ASIC
If selected band = GSM1900
Oscilloscope:
Check voltages for V7800:
Voltage at C7802 = 2.5V ?
Volta
g
e at C7800 = 0V ?
Yes
Spectrum Analyzer:
1)
Check external LNA V7800:
TP: OUT-V7800
Output signal > Pref +14dB
No
Yes
Receiver
Fault Finding Tree
part 9
Note
1)
:
RF levels are dependent on RF probe and have to be validated
with a known good sample.
RF ASIC N7500 seems to be
defective. Exchange N7500.
Spectrum Analyzer:
1)
Check balun T7800 and matching network:
TPs: INM_P_RX / INP_P_RX
Both output signals > Pref +12dB
No
Yes
No
Yes
Yes
Change T7800
Yes
Spectrum Analyzer:
1)
Check SAW filter Z7801:
TP: OUT-Z7801
Output signal > Pref - 3.5dB
Change Z7801
No