User Guide

CCS Technical Documentation Troubleshooting — RF
RH-17
Issue 1 04/2003 Nokia Corporation Confidential Page 49
Table 10: RF Probing for AMPS Back End Receiver
Cell RX saw (Z751) out=Alfred
(N750) mixer in
TP37 Loss=1-3 dB
through SAW
filter
Z751, N750, L757 and
C758.
UHF LO at 1009.62 MHz in Cell
CDMA/AMPS for channel 384
TP38 Approx.
-3 dBm
Check to see if LO is
present. If no LO is
present, check L771, R505
and L520. Refer to Table 5
for additional UHF LO
troubleshooting.
Alfred (N750) Mix_Out= at 128.1
MHz Alfred (N750) IFA_In=
TP39
Rx 1
st
IF at
128.1 MHz is
usually
-5.0 to –7.0
dBm less than
original Rx
input ampli-
tude setting at
RF Test Set.
Check LP filter compo-
nents L753, C759, C766
and L770.
Alfred (N750) IFA_In=
Alfred (N750) AMPS out=
TP40 This point not 50
ohms. Will
measure approx
+ 3 dB gain from
IFA Amplifier.
Using results
fromTP39 as ref-
erence.
Ensure IF_SEL low for CDMA and high for
AMPS, as in Table 11), N750, R765, C750,
L757 and also reference next step(TP41) to
ensure that impedance matching compo-
nents from N750 to Z752 are correct.
Alfred (N750) AMPS out=
Amps RX IF filter(Z752)
in=
TP41 Same results as
above if match-
ing components
are correct
Check Z752, C784, L764, C781, L762, C783,
C786, C761, L754, C782 and C767 also
ensure dc voltage Vrx is present at L762.
AMPS RX IF filter (Z752)
in=
AMPS RX IF filter (Z752)
out=
TP42 This point not 50
ohms. Will
measure Loss of
=2-4 dB through
Crystal filter
Z752, L765, C777, L766, C778, L768, L767,
C779, N701 (VR5, VR7, VIO)
AMPS RX IF filter (Z752)
out=
Batman (N701) in=
TP43
TP44
You will meas-
ure usually –10
dBm less than
previous test
point.
Z752, L765, C777, L766, C778, L768, L767,
C779, N701 (VR5, VR7, VIO)