Nokia NPD-4 Series Technical Documentation Manual page 35

CCS Technical Documentation
Table 7: RF probing for Cell CDMA and AMPS front end receiver
Probing
Probing point location on
board
Diplexer (Z805) 8, Figure 7
out= cell duplexer
(Z803) in.
Cell duplexer 32, Figure 5
(Z803) out= Alfred
(N750) in
Alfred (N750) LNA 33, Figure 7
out= cell RX saw
(Z751) in
Cell RX saw (Z751) 34, Figure 7
out=Alfred (N750)
mixer in
UHF LO at 1009.62 10D, Figure 7.
MHz in Cell Can probe on
CDMA/AMPS for top of plastic
channel 384 to check for
presence of LO,
but won't read
accurate
power
Issue 1 02/2003
Probed absolute
power (dBm) or gain/
loss (dB)
Loss=0.5 dB through
diplexer
Loss=2-4 dB through
duplexer
Gain=12-14 dB for
high gain mode
(GAIN_
CTL=high. Use RF AGC
status window to
monitor state.),
Loss=-3 to –5 dB for
low gain
Loss=1-3 dB through
SAW filter
Approx –3 dBm
Nokia Corporation
Troubleshooting — RF
What to check if RF power not
correct (soldering, shorts, DC
power applied if active, correct
voltage of DC signals, otherwise
replace)
X800, L812, C801, Z805, Z803
Z803, L750, N750 (VRX)
N750 (Also ensure BAND_SEL low
as in Table 9. Also IF_SEL low for
CDMA and high for AMPS, as in
Table 9. Ensure GAIN_CTL is high if
RX power is below the LNA switch
point.), Z751, C755, L752, C757,
R764, C753, R768, C756
Z751, N750, R765, C750, R768,
C756, L757, C758
Check to see if LO is present. If no
LO is present, check R515, C511,
C501, C532. Make sure there is
2.7V at TP 10B. If voltage is less
than 2.6V, then refer to baseband
regulator troubleshooting. If volt-
age is 2.7V, check G502 at TP 10A
with a FET probe to see if UHF LO is
present. Check that the 19.2MHz
clock is present at TP 10C. If LO is
present but unlocked, check C518,
C508, R508, R503, C509, R550,
and C550. Pay particular attention
to C508, as it is easily damaged. If
LO is present and locked, but
doesn't appear at TP 10D, then
check R505, R507, L771.
Confidential
NPD-4
Page 35