User Guide

Nokia Customer Care Troubleshooting - RF

6015/6015i/6016i/6019i (RH-55), 6012 (RM-20)

RF Troubleshooting

When troubleshooting the receiver, first check the RX_AGC PDM value. The AGC value

should be close to the typical values (see "RF AGC Status" on page 26). The RX AGC tries

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, the AGC is compensating

for extra loss in another component. If the AGC PDM values are normal and 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 give an indication of where to start probing. 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;

therefore, adjust the absolute measurements accordingly. Also, adjust if using a probe

attenuator.

Where a range is given for loss, typically the higher loss occurs at the band edges.

Probing 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

impedance (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 are the same for a CW signal as for CDMA.

Note: After opening the shield lids, always replace them with new lids.