Nokia 2355 Service Manual

Nokia Customer Care

2355 (RM-121)

Mobile Terminal

RF Description and

Troubleshooting

2355 (RM-121) RF Description and Troubleshooting Nokia Customer Care

Contents Page

Mobile Terminal Components ..................................................................................................................... 3

Preliminary RF Troubleshooting.................................................................................................................. 4

Mobile Terminal Cannot Make a Call ....................................................................................................4

Tx Power Low ................................................................................................................................................ 4

Transmitter Block Diagram .......................................................................................................................5

Transmitter Schematics .............................................................................................................................6

Transmitter Troubleshooting ....................................................................................................................8

CELL Tx Setup............................................................................................................................................. 8

Failed Test: Tx PA Detector ................................................................................................................. 10

Tx RF Test Points ........................................................................................................................................12

Tx AGC Tuning ............................................................................................................................................15

Receiver Troubleshooting ........................................................................................................................16

Receiver Schematics .................................................................................................................................17

Turning on the Rx Path ........................................................................................................................ 19

Switching the Rx Gain, IF, and IP States ............................................................................................20

Receiver Troubleshooting ........................................................................................................................21

Receiver RF Troubleshooting Test Points ............................................................................................22

Receiver IF Troubleshooting Test Points ............................................................................................24

Cell Receiver Check from RF to IQ ........................................................................................................26

Receiver Diagnostic using Signal Tracing and Call Box.............................................................. 27

Rx Front-End IC (N7150) DC Troubleshooting ..................................................................................28

Synthesizer Troubleshooting ..................................................................................................................28

Synthesizer Block Diagram ................................................................................................................. 29

Synthesizer Schematic .............................................................................................................................30

Synthesizer Troubleshooting Setup ......................................................................................................31

19.2 MHZ VCTCXO Reference Clock .....................................................................................................33

VCTCXO Manual Tuning ...........................................................................................................................33

UHF Synthesizer Test Points ...................................................................................................................37

UHF Synthesizer Schematic ....................................................................................................................38

Incorrect UHF Frequency ..................................................................................................................... 39

Rx VHF ........................................................................................................................

Rx VHF Schematic .....................................................................................................................................40

Incorrect Rx VHF Frequency ............................................................................................................... 40

Tx VHF ...........................................................................................................................................................41

Tx VHF Schematic ......................................................................................................................................42

Incorrect Tx VHF Frequency................................................................................................................ 43

FM Radio Troubleshooting ......................................................................................................................44

FM Radio Troubleshooting Setup ..........................................................................................................44

..................................39

2355 (RM-121)

Nokia Customer Care RF Description and Troubleshooting

Mobile Terminal Components

Figure 1 illustrates the main components of the 2355.

RF connector

Cell isolator

Rx IC

PA PMIC

DC-DC converter

Cell duplexer

Cell Rx RF SAW filter

Cell Tx PA

Cell Tx SAW filter

Tx Up- converter

UIM card

UPP (BB)

RF IF CDMA filter

VCO

Rx Down- converter

VCTCXO

UEM (BB)

Figure 1: Component layout (bottom)

2355 (RM-121) RF Description and Troubleshooting Nokia Customer Care

Preliminary RF Troubleshooting

The following sections identify steps to troubleshoot some common RF issues.

Mobile Terminal Cannot Make a Call

Verify the following items if the mobile terminal cannot make a call:

1. The mobile terminal is in Normal Mode (i.e., the mobile terminal is searching for a signal, net server is on).

2. The Preferred Roaming List (PRL) is loaded into the mobile terminal.

3. The mobile terminal is tuned and has passed tuning. Read the tuning parameters using the Batch Tune component in Phoenix. An untuned mobile terminal has all zeros in the tuning file.

4. The call box channel is set for a channel in PRL.

5. The SID is correct and entered into the mobile terminal.

6. The VCTCXO is centered as described in "VCTCXO Manual Tuning" on page 33

7. The transmitter and receiver are working properly in Local Mode. See

Tx Power Low

Complete the following steps if Tx power is low:

1. Use Phoenix to turn on the transmitter in Local Mode.

2. Perform a visual inspection of the PWB under a microscope to check for the

3. Look for the presence of a Tx signal on a spectrum analyzer at the correct

"Transmitter Troubleshooting" on page 8 and "Receiver Troubleshooting" on page 16 for detailed information.

proper placement, rotation, and soldering of components.

frequency.

• If a signal is present but off-frequency, check the synthesizers for proper

frequency and amplitude. One of the synthesizers may be unlocked or the VCO has no output signal.

• If a signal is not present or is present but is low in amplitude, check the

probing diagrams to determine where in the chain the fault occurs.)

4. Ensure that the power supplies to the Tx have the correct voltage.

5. Ensure that the AGC PDMs are set for the desired Tx power and that the AGC voltages are correct.

2355 (RM-121)

Nokia Customer Care RF Description and Troubleshooting

Transmitter Block Diagram

Following is the block diagram for the Tx RF system. I

TP1

TP4

TP2 TP3

Figure 2: Tx system block diagram

2355 (RM-121)

Nokia Customer Care RF Description and Troubleshooting

Transmitter Schematics

The following schematics are for general reference only. See the Schematics chapter for detailed versions.

Figure 3: Transmitter schematic 1

2355 (RM-121) RF Description and Troubleshooting Nokia Customer Care

Figure 4: Transmitter schematic 2

2355 (RM-121) RF Description and Troubleshooting Nokia Customer Care

Transmitter Troubleshooting

CELL Tx Setup

Use the following procedures to prepare for CELL Tx troubleshooting using Phoenix.

1. Connect RF test connector to a call box.

2. Connect the phone to a PC using the dummy battery adapter, and connect a power supply.

3. Open the Troubleshooting menu, and click Phone Control.

The Phone Control dialog box appears.

4. On the Phone Control dialog box, click the LOCAL button in the Phone State area to put the phone into Local Mode.

Figure 5: Phone Control dialog box

5. Open the Troubleshooting menu, point to RF, and click CDMA Control. The RF Main Mode dialog box appears.

6. Select the following values on the RF Main Mode dialog box:

• Band = Cell (CDMA)

• Channel = 384

• Mode = Rx/Tx

2355 (RM-121)

Nokia Customer Care RF Description and Troubleshooting

Figure 6: RF Main Mode dialog box

7. Click Set.

Note: Be sure that the “RF Main Mode set successfully” message appears in the status bar.

8. Open the Troubleshooting menu, point to RF, and click CDMA Control.

The CDMA Control dialog box appears.

Figure 7: CDMA Control dialog box for Cell Tx troubleshooting

9. Select the following values on the CDMA Control dialog box.

• State = Rho ON

• Band = Cell

• Radio Configuration = Mode 1: IS-95 Voice

• Select the Set default PDM values check box.

10. Click Execute.

11. At this point you should be able to measure Tx Pout at the RF connector. The cell band Tx Pout = 0 to 2 dBm. If you do not see these values, set the AGC PDM for 25 dBm and probe the Tx path to figure out where in the path the fault occurs.

12. Open the Troubleshooting menu, point to RF, and click PDM Control.

The RF PDM Control dialog box appears.

2355 (RM-121) RF Description and Troubleshooting Nokia Customer Care

Figure 8: RF PDM Control dialog box for Cell troubleshooting

13. Click Read Phone to update the values.

14. Configure the spectrum analyzer using the following values:

• Center Frequency = 836.52 MHz

• Span = 100 MHz

• RF LVL Amplitude = 20 dBm

• Attenuation = Auto

• BW = Auto

Adjust the following PDM field values on the RF PDM dialog box:

• Set PA Gain State to High

• Adjust Tx RF AGC PDM to around –250

• Adjust Tx IF AGC PDM to around –250

• Set Output level to +23dBm on CH-384 and monitor the current between

590mA and 660mA.

Failed Test: Tx PA Detector

1. Use Phoenix to set the phone in Local Mode, and activate the Tx with default output power. The output power at the RF test connector should read 9 dBm +/- 4 dB.

2. Use a voltmeter on DC, and probe the detector output at C813. The voltmeter should read approximately 1.4 V. If not, replace the detector (N803).

2355 (RM-121)

Nokia Customer Care RF Description and Troubleshooting

Good output

Figure 9: The output of the mobile terminal on a spectrum analyzer should look like the figure on the left

Bad output

If using the AAS-10 probe with the phone connected to the call box, the amplitude should be approximately -7 dBm at the antenna test point on the top of the PWB.

2355 (RM-121) RF Description and Troubleshooting Nokia Customer Care

Tx RF Test Points

Figure 10 and Figure 11 are the transmitter DC/RF test points. See Table 1 on page 14 for test point descriptions and values.

214

TP12

PNMIC DC-DC

TP11

TP13

Figure 10: Tx DC/RF test points - PA section

TP3

TP4

2355 (RM-121)

Nokia Customer Care RF Description and Troubleshooting

Following are the Tx DC/RF test points for the N7000 Tx Section

214

TP5

TP91

TP6

TP10

TP7

TP9

N7000 Tx

Figure 11: Tx DC/RF test points - N7000 section

Tx SAW

TP2

TP3

TP8

2355 (RM-121) RF Description and Troubleshooting Nokia Customer Care

Table 1 shows the Tx DC/RF test points to probe (see Figure 10 and Figure 11) when troubleshooting the cell transmitter path. It is recommended that you follow the steps in order.

Table 1: Tx DC test points

Typical Value/

Test Point FUnction

Frequency HP85024A

TP1 Z7000 pin 1

TP2 Z7000 pin 3

TP3 Z7400 In

TP4 Z7400 Out

TP5 C7002 IF - Out -29 dBm/ 1MHz

TP6 VR5 2.75V dc VHF VCO/PLL, IQ modulator

TP7 VR7 2.75V dc UHF PLL supply from UEM

TP8 VR2 2.75V dc Mixer, driver, and IF supply

N7000 - Out -40 dBm/ 1MHz

836.52MHz

PA - In -26 dBm/ 1MHz

836.52MHz

PA - Out 5.0 dBm/ 1MHz

836.52MHz

Iso - Out 2.5 dBm/ 1MHz

836.52MHz

228.6MHz

Typical Value/ Frequency Prod Probe

-13.2dBm/

836.52MHz

-15.4 dBm/

836.52MHz

18.3 dBm/

836.52MHz

10.3 dBm/

836.52MHz

-24 dBm/

228.6MHz

Comments

Output of N7000 Driver, Input to Tx SAW Filter

Output of Tx SAW, Input to PA

Input to Isolator

Output of Isolator, Input to Duplexer

Tx IF probing point at IF filter

supply from UEM

from UEM

TP9 R7002 TP91 R7001

TP10 VIO-Tx 1.8V Supply for digital circuits

TP11 VBAT 3.2V dc Battery voltage (nominal

TP12 VCC 3.1V dc (High Gain) Main PA supply voltage

TP13 C7407 VG/Vref 4.6V dc (Enable) PA gate voltage (Enable/

VAGC-RF VAGC-IF

0.2 to 1.8V dc Tx AGC control voltage from UPP.

0.2V = Max Gain

1.8V = Min Gain

from UEM

voltage 3.7V dc)

from PMIC. Lgain=0.8V, Mgain=1.25V, Hgain=Vbat

Disable). Disable=0V

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