
NPD-4
Troubleshooting — RF
CCS Technical Documentation
Page 36
Nokia Corporation Confidential
Issue 1 02/2003
Table 8: RF probing for AMPS back end receiver
Probing point
Probing
location on
board
Probed absolute
power (dBm) or gain/
loss (dB)
What to check if RF power not
correct (soldering, shorts, DC
power applied if active, correct
voltage of DC signals, otherwise
replace)
Alfred (N750)
mixer out= AMPS
RX IF saw (Z752)
in
36, Figure 6
This point not 50
ohms. Will
measure approx
-28 dBm for -52 dBm
input and RX AGC
PDM=225.
N750 (Also ensure BAND_SEL low
as in Table 9. Also IF_SEL low for
CDMA and high for AMPS, as in
table 3d.), R765, C750, L771, R768,
C756, L770, L757, C758, L755,
C769, R750, L753, C759, C766,
C784, L764, C781, Z752
AMPS RX IF filter
(Z752) out= Bat-
man (N701) in
37, Figure 6
This point not 50
ohms. Will
measure approx
-46 dBm for -52 dBm
input and RX AGC
PDM=225.
Z752, L765, C777, L766, C778,
L768, L767, C779, N701 (VR5, VR7,
VIO)
Batman (N701)
out= UEM (D200)
in
40, Figure 6
See Table 6, RSSI most
useful.
N701 (VR5, VR7, VIO, ensure 1.35v
on VREFRF01 as in Table 9, also
check RX_IF_AGC as in Table 9),
R706, C704, R705, R704, V701,
C716, L701, C702, C715, R702,
C714, R703, C701,
VHF LO at 256.2
MHz
39, Figure 6
N701, C701, C714, R703, R702,
C715, R704, V701, C716, L701,
C702, R705, C706
Table 9: DC probing for receiver
Item to check
Setting
DC probing
location on
board
DC voltage
Items to check if voltage
incorrect
RX IF AGC
See Table 6 for
PDM settings
60, Figure 6
See Table 6 for
typical voltages
D400, R435, C428, C435, N701
BAND_SEL
High=PCS
Low=Cell
54, Figure 7
High=2.4vmin,
Low=0.3v max
N701, N750, R768, C756, G502
GAIN_CTL
High=LNA high
gain, Low=LNA
low gain (both
Cell & PCS)
55, Figure 7
High=2.4vmin,
Low=0.3v max
N701, N750, R764, C753
IF_SEL
High=
AMPS, Low=
CDMA
56, Figure 7
High=2.4vmin,
Low=0.3v max
N701, N750, R765, C750
VREFRF01
fixed
57, Figure 6
1.35 v
D200, C706, N701