Nokia NSW-5 Series Service Manual page 242

NSW-5
Disassembly and Troubleshooting Instructions
Y
Check level of IF1 signal
(116.19 MHz ) from MXR
output (N721) pin no.14
P: ≅ –43 dBm
Y
Check input level of
EROTUS IF amplifier
(116.19 MHz )
from resistor R744
P: ≅ –48 dBm
Y
Check input level
of IF2–filters
(450 kHz ) from
capasitor C770
P: ≅ –36 dBm
Y
Check input level of
buffer ( 450 kHz ) from
capasitor C768
P: ≅ about 6 dB less
than at C770
(IF2–filters input level)
Y
Check output level of
buffer from
resistor R798
P:≅ –13 dBm
Y
TDMA 1900
RX–chain is OK.
Start baseband
troubleshooting
(signal go next to
COBBA IC N250)
Page 36
N Check level of LO signal
(2076.21 MHz ) from LO
input (N721) pin no.1
P: > –7 dBm
Y
Change frontend N721
N
Change IF1–filter Z741
N Check level of OSC–sinal
(19.44 MHz ) from
EROTUS (N750) pin no.24
P: ≅ +3 dBm
Y
Change
EROTUS
N750
N
Change IF2–filter(s)
Z750 and/or Z751
N
Change
EROTUS
N750
E Nokia Mobile Phones Ltd.
PAMS Technical Documentation
N
Start synthesizer
troubleshooting
Note!
Check all components
around N721
Note!
Check all components around filter
N
Start synthesizer
troubleshooting
Note !
Check components and
voltages around EROTUS
and also AGC1 line
Note !
Check comp. R765 & C770
Note !
Check comp. R798, C750 &
C751 and also check voltages
around EROTUS
Issue 1 10/00