Sn Amps Rx Dc Offset I (Or Q); Test Tx Start Up Current; Test Tx Start Up Amplitude; Tn Vctcxo Frequency - Nokia NPD-4 Series Technical Documentation Manual
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CCS Technical Documentation
SN AMPS RX DC Offset I (or Q)
This is one of the phone's self tunings which measures and adjusts the cell band AMPS
receiver DC offsets until they are within the limits.
The DC offset is returned for I (or Q).
Manual Verification: Use RF Tuning window in Phoenix, set mode to "self tune" and
choose this tuning.
Troubleshooting: Check Batman (N701) and supporting components.
Test TX Start up Current
This test turns on the AMPS transmitter (PCS transmitter for PCS-only phones) and mea-
sures current of the whole phone, which can detect some assembly errors.
Manual Verification: Set the phone to local mode and turn on the AMPS transmitter. Set
the PDM values as listed in Table 1 for AMPS Power Level 5 (for PCS, set output power to
+12 dBm). Read the phone's current on the power supply and check to see that it is
within the limits. If the power supply does not display current draw, use a current meter
in series with the phone. If the phone powers down when the mode is set, it may be that
the phone is drawing more current than the current limit setting on the power supply.
Troubleshooting: If current is very high, there may be a short circuit on the phone caused
by a solder bridge, a failed component that is internally shorted, a component placed
with the wrong rotation (which shorts two nodes that shouldn't be), or some other rea-
son. Short circuits can be difficult to find, but one of the easiest methods is to use a
thermal camera and look for hot spots that are not normally hot, and look for the hottest
spots. A visual inspection can find solder bridges or wrong component rotations. A failed
component can be found by functional tests of the phone's sub-blocks.
Test TX Start up Amplitude
This test turns on the AMPS transmitter (PCS transmitter in PCS-only phones) and checks
for the presence of a TX signal with an amplitude within a specified range. A wide range
is allowed since the transmitter is not yet tuned.
Manual Verification: Set the phone to local mode and turn on the AMPS transmitter set
to channel 384. Set the AGC PDM values as in test 17. Look for an output signal at
836.52 MHz with an amplitude within the limits. The frequency of the signal may not be
accurate since the VCTCXO has not yet been tuned.
Troubleshooting: Check proper placement, rotation, and soldering of the components in
the TX chain, as shown in Figure 5. Check for the presence of LO tones as listed in
Table 2. Check for presence of a TX signal at each point in the TX chain, probing accord-
ing to Table 2.
TN VCTCXO Frequency
The purpose of this tuning is to determine what the AFC DAC value needs to be in order
Issue 1 02/2003
Nokia Corporation
Troubleshooting — RF
Confidential
NPD-4
Page 13
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Troubleshooting
