Nokia 3105 Servicehandbuch
CCS Technical Documentation
Troubleshooting - RF
RH-48
Issue 1 11/2003
© 2003 Nokia Corporation Confidential
Page 41
Tuning Descriptions
Tuning Title
Description
Troubleshooting
Tx Detector
This is one of the phone's self-tests
which gives either a pass or fail result
only. The phone transmits at several
power levels and checks the ADC value
of the power detector. The ADC value is
measured first for a set of AGC values,
then each AGC value is changed one at
a time to make sure that the ADC
changes as each AGC is changed indi-
vidually.
which gives either a pass or fail result
only. The phone transmits at several
power levels and checks the ADC value
of the power detector. The ADC value is
measured first for a set of AGC values,
then each AGC value is changed one at
a time to make sure that the ADC
changes as each AGC is changed indi-
vidually.
Check the AGC voltages and components of
the associated PDMs. For problems with the
IF or RF AGC, also check Jedi and supporting
components. For PA AGC problems, also
check the PA and supporting components. If
all of the above cases fail, troubleshoot the
Tx chain. If all the output powers are pass-
ing, then perhaps the test is failing because
the ADC voltage is wrong (which at this
point we cannot read, so we are measuring
the actual output power). If the voltages are
wrong, then check the power detector at
N805, C803, C807, and also Jedi. If the volt-
ages are correct and it still fails, check the
UEM ( D200).
the associated PDMs. For problems with the
IF or RF AGC, also check Jedi and supporting
components. For PA AGC problems, also
check the PA and supporting components. If
all of the above cases fail, troubleshoot the
Tx chain. If all the output powers are pass-
ing, then perhaps the test is failing because
the ADC voltage is wrong (which at this
point we cannot read, so we are measuring
the actual output power). If the voltages are
wrong, then check the power detector at
N805, C803, C807, and also Jedi. If the volt-
ages are correct and it still fails, check the
UEM ( D200).
Cell PA Temp
This is one of the phone's self tunings,
which reads the ADC voltage of a ther-
mistor R821, 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.
which reads the ADC voltage of a ther-
mistor R821, 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 R821 and
D200. If a short is suspected, check the cell
PA first. If an infrared camera is available,
this is one of the easiest methods to detect
a short.
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 R821 and
D200. If a short is suspected, check the cell
PA first. If an infrared camera is available,
this is one of the easiest methods to detect
a short.
Cell Rx DC Offset I
(or Q)
(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.
which measures and adjusts the cell
band CDMA receiver DC offsets until
they are within the limits.
Check Yoda (N701) and supporting compo-
nents.
nents.
Tx Start-up Current
This test turns on the transmitter and
measures current of the whole phone,
which can detect some assembly errors.
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
should not be, or some other reason. A vis-
ual inspection can find solder bridges or
wrong component rotations. A failed com-
ponent can be found by functional tests of
the phone's sub-blocks.
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
should not be, or some other reason. A vis-
ual inspection can find solder bridges or
wrong component rotations. A failed com-
ponent can be found by functional tests of
the phone's sub-blocks.
Tx Start-up Amplitude
This test turns on the transmitter 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.
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 the presence of a Tx signal at each point
in the Tx chain.
dering of the components in the Tx chain.
Check for the presence of LO tones. Check
for the presence of a Tx signal at each point
in the Tx chain.