Nokia 2270, 2272, 2275, 2285 Manuale Di Servizio
CCS Technical Documentation
Troubleshooting - RF
RH-3
Issue 1 06/2003
Nokia Corporation Confidential
Page 5
RF Troubleshooting
RH-3/RH-3P General Troubleshooting Notes
When troubleshooting the receiver, first check the RX_AGC PDM value. The AGC value
should be close to the typical values in the tables. Since the RX AGC will try to keep a
constant amplitude at the output of the receiver chain, if the AGC value indicates an
AGC gain that is substantially higher than normal, then the AGC is compensating for
extra loss in another component. If the AGC PDM values are normal, but there is still a
problem, check the actual AGC voltages. RF probing at specific locations in the chain can
then help to pinpoint the source of the problem.
should be close to the typical values in the tables. Since the RX AGC will try to keep a
constant amplitude at the output of the receiver chain, if the AGC value indicates an
AGC gain that is substantially higher than normal, then the AGC is compensating for
extra loss in another component. If the AGC PDM values are normal, but there is still a
problem, check the actual AGC voltages. RF probing at specific locations in the chain can
then help to pinpoint the source of the problem.
Likewise, when troubleshooting the transmitter, first check the measured output power
and AGC values, which will give an indication of where to start probing.
and AGC values, which will give an indication of where to start probing.
Although the tables list power levels for many combinations of AGC values, it is generally
only necessary to check one combination. The extra information is provided in case it
may be useful in an unexpected situation. Likewise, although probing points and signal-
level information are given for each point in the receiver and transmitter chains, the
troubleshooter is not expected to probe each point on every phone — only the suspected
trouble spots.
only necessary to check one combination. The extra information is provided in case it
may be useful in an unexpected situation. Likewise, although probing points and signal-
level information are given for each point in the receiver and transmitter chains, the
troubleshooter is not expected to probe each point on every phone — only the suspected
trouble spots.
Absolute power measurements were made with an Agilent (HP) 85024A active high-
impedance probe. Other probes can be used (but should be high-impedance so that the
measurement does not load the circuit) but may very well have a different gain; there-
fore, adjust the absolute measurements accordingly. Also, adjust if using a probe attenu-
ator.
impedance probe. Other probes can be used (but should be high-impedance so that the
measurement does not load the circuit) but may very well have a different gain; there-
fore, adjust the absolute measurements accordingly. Also, adjust if using a probe attenu-
ator.
Where a range is given for loss, typically the higher loss occurs at the band edges. Prob-
ing is not a very accurate method to measure absolute power; therefore, you cannot
expect measured results to exactly match the numbers listed here.
ing is not a very accurate method to measure absolute power; therefore, you cannot
expect measured results to exactly match the numbers listed here.
Power depends on the impedance of the circuit. For example, if a filter has a nominal loss
of 5 dB, then straightforward probing on the input and output, then subtracting, might
not result in 5 dB because the input impedance might be different from the output
impedance. Most components in the RF section have the same input and output imped-
ance (50 ohms), but where this is not the case, absolute power is noted in the tables in
dBm, rather than loss or gain in dB.
of 5 dB, then straightforward probing on the input and output, then subtracting, might
not result in 5 dB because the input impedance might be different from the output
impedance. Most components in the RF section have the same input and output imped-
ance (50 ohms), but where this is not the case, absolute power is noted in the tables in
dBm, rather than loss or gain in dB.
When testing the CDMA receiver, it is easier to inject a CW tone into the receiver. The
gains and losses will be the same for a CW signal as for CDMA.
gains and losses will be the same for a CW signal as for CDMA.
Note: After opening the shield lids, allways replace them with new lids.
Conditions of Phone
TX Power Low
If TX power is low, turn on transmitter in local mode using Phoenix. Check: