User Guide

NSW-4
Disassembly & Troubleshooting
PAMS Technical Documentation
Page 29
Issue 1 Final Draft
08/00
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TDMA 1900RX
Apply 1960.02 MHz
–50dBm signal to
Antenna interface
Check 3 multiplier
output level at C745
V: >80 mVpp
N
N
N
Check input level
of duplex filter (Z960)
P:
≅
–50dBm
Check input level of
frontend N721, pin7
P:
≅
–55dBm
Check output level at
LNA out, pin10
P:
≅
–50dBm
Check RF level of
COBBA_D pin no 10
Check UHF Vcnt
V: 2.0...3.5V
N870, pin3
Start synthesizer
troubleshooting
TDMA1900
RX–chain is OK
Y
N
N
Y
N
Start synthesizer
troubleshooting
Change diplexer Z970
Note!
Check all soldering and components
in antenna circuit before changing
N
Y
Y
Change duplex filter or
L721
Note!
Check all soldering and discrete
components of frontend.
Change N721
Y
Note!
AG2 is on =low gain state
Check MXR RF level
pin12
P:
≅
–55dBm
Change RX band filter
Z726
Check MXR IF level,
F= 116.19 MHz,
pin14
Check input level of
frontend N721, pin1
F=2076.21 MHz
Note!
Check all soldering
N
Y
Note!
Check all components around of N721
N
Y
N
Y
Change N721
Start synthesizer
troubleshooting
N
Y
NOTE! If RX800 is OK, then RX1900
troubleshooting should be concentrated only on
Z960 and N721 area and surrounding components.