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CCS Technical Documentation
Troubleshooting - RF
RH-3
Issue 1 06/2003
Nokia Corporation Confidential
Page 51
Cell PA Temp
This is one of the phone's self tunings,
which reads the ADC voltage of a ther-
mistor R808, and checks to make sure
the phone is at room temperature. The
reason for this is that a phone should
not be tuned while it is hot or cold.
If the phone was recently transmitting in
Cell band at full power for an extended
period of time, it is probably hot for that
reason. Let it cool down for a few minutes,
then try again. If it still fails, there may
either be a short on the board or else a
problem with the PA Temp circuitry. To
check PA Temp circuitry, check R808, C232,
R202, and D200. If a short is suspected,
check the cell PA first. If an infrared camera
is available, this is one of the easiest meth-
ods to detect a short.
Cell RX DC Offset I
(or Q)
This is one of the phone's self tunings,
which measures and adjusts the cell
band CDMA receiver DC offsets until
they are within the limits.
Check Yoda (N701) and supporting compo-
nents.
TX Start-up Current
This test turns on the transmitter (PCS
transmitter for PCS-only phones) and
measures current of the whole phone,
which can detect some assembly errors.
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 reason. 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.
TX Start-up Amplitude
This test turns on the 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.
Check proper placement, rotation and sol-
dering of the components in the TX chain.
Check for the presence of LO tones. Check
for presence of a TX signal at each point in
the TX chain.
Tuning Title
Description
Troubleshooting