Nokia NPD-4 Series Technical Documentation Manual page 37

CCS Technical Documentation
Probing
Probing point location on
board
Diplexer (Z805) 23, Figure 7
out= PCS duplexer
(Z804) in.
PCS duplexer 42, Figure 7
(Z804) out= Alfred
(N750) LNA in
Alfred (N750) LNA 43, Figure 7
out= PCS RX saw
(Z750) in
PCS RX saw 44, Figure 7
(Z750) out=Alfred
(N750) mixer in
UHF LO at 2088.1 10D, Figure 7.
MHz for PCS Can probe on
channel 600 top of plastic
to check for
presence of LO,
but won't read
accurate
power
Issue 1 02/2003
Table 10: RF probing for PCS front end receiver
Probed absolute
power (dBm) or gain/
loss (dB)
Loss=0.5 dB through
diplexer
Loss=1-3.5 dB
through duplexer
Gain=12-14 dB for
high gain, Loss=-3 to
–5 dB for low gain,
use AGC status win-
dow to monitor gain
status
Loss=1-4 dB
Approx –3 dBm
Nokia Corporation
Troubleshooting — RF
Where to start checking if RF
power not correct (soldering,
shorts, DC power applied if
active, correct voltage of DC
signals, otherwise replace)
X800, L812, C801, Z805, Z804,
Z801, C752, L751, N750. (If all
these are ok and it passes con-
ducted test but fails radiated test,
then check the following: L802,
R823, L803, R824, X811, X810,
X814, L851)
Z804, Z801, Z805, C752, L751,
N750 (including check for proper
voltages on Alfred signaling as in
table 3c)
N750 and supporting components
(Also ensure BAND_SEL high as in
Table 9. Also IF_SEL low for CDMA
as in Table 9. Ensure GAIN_CTL
high if RX power is below the LNA
switch point), Z750
Z750, N750 and supporting com-
ponents (including check for proper
voltages on Alfred signaling as in
Table 9)
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. 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 partic-
ular attention to C508, as it is eas-
ily damaged. If LO is present and
locked, but doesn't appear at TP
10D, then check R505, R507, L771.
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NPD-4
Page 37