User Guide

Nokia Customer Care

RM-1

RF Troubleshooting

Company Confidential

7A - 59

Issue 1

• Check if the frequency of the RX VCO is as expected. If the VCO signal is not found try to use

wider span setting. Output level of the VCO should be about -20…-30 dBm.

3.2.2.10.1.1 Replace RX VCO G7500

3.2.2.10.2 Replace balun T7501

3.2.2.11 VCTCXO frequency and output level correct?

• Measurement can be done with an oscilloscope and a probe.

• Connect the probe to C7529 (or C7582)

• The frequency of the VCTCXO should be quite exactly 38.4 MHz and level about 0.5 - 0.9 Vpp.

Example of the correct VCTCXO output signal is presented in figure

6.5.1 "VCTCXO Output

(DC Offset 1.24 V)".

3.2.2.11.1 VXO-voltage ok? (=Vdig).

• Measurement can be done with an oscilloscope and a probe.

• Connect the probe to C7529 (or C7582)

• The frequency of the VCTCXO should be quite exactly 38.4 MHz and level about 0.5 - 0.9 Vpp.

Example of the correct VCTCXO output signal is presented in figure

6.5.1 "VCTCXO Output

(DC Offset 1.24 V)".

3.2.2.11.2 BB AFC-voltage ok?

• Measurement can be done with an oscilloscope and a probe

• Connect the probe to R7509 (or C7533)

• AFC-voltage may vary between 0.1 - 2.3 V. Typical value is 1.2 V. Phoenix “RF Controls” tool

can be used to change the AFC value. Voltage level should be about 0.1 V with AFC value -

1024 and about 2.3 V with AFC value 1023.

3.2.2.11.3 Replace VCTCXO G7501

3.2.2.12 Replace Hinku ASIC (N7500)

3.2.3 Is RAP3G ASIC getting ok VREFCM-signal from Hinku (N7500)? Signal level ok?

• GSM receiver has to be active before VREFCM signal can be measured. Procedure is

explained in chapter “GSM RX chain activation for manual measurements”.

• Measurement can be done with an oscilloscope and a probe.

• Connect the probe to J7516.