PAMS
Technical Documentation
NSC/W–1/3
Disassembly & Troubleshooting Instructions
Page 21
Original 11/99
Receiver Fault AMPS
Apply 879.00 MHz
–116dBm, 8kHz dev 1
kHz sine signal to
external RF–connector
X991.
Check 3 multiplier
output level TP2LU
V: >150 mVpp ?
N
N
Check input level
at duplex filter (Z910)
input
Check input level at
frontend (N701) input
pin7
Check output level at
LNA out
pin10
P:~–27 dBm
Connect EXT HS to
audioanalyzator, open
audio
AF: 1 kHz sine signal,
meas SINAD
AF: >12dB
Check UHF Vcnt
V: 2.0 ..2.5 V
Start synthesizer
troubleshooting
AMPS
Y
N
N
Y
N
Start synthesizer
troubleshooting
Change EXT RF
Connector
Note!
Check all soldering and components
in antenna circuit before changing
N
Y
Y
Change duplex filter or
L701
Note!
Check all soldering and discrete
components of frontend.
Change N701
Y
Note!
AG2 is on
Check MXR RF level
pin12
P:~0.2 dB less than in
Change RX band filter
Z701
Note!
Check all solderings
N
Y
N
RX Chain OK
TP31
n750, pin 42
Y
Apply 879.00MHz
–50dBm sine sign.
to external RF
connector X991
P: ~–47 dBm
LNA output
pin no. 10
P: ~–47 dBm