Nokia 3105 Service Manual 9rh48rf

CCS Technical Documentation

RH-48 Series Transceivers

Troubleshooting - RF

RH-48

Troubleshooting - RF CCS Technical Documentation

Contents

Page No

RF Troubleshooting ........................................................................................................3

RH-48 General Troubleshooting Notes........................................................................3

Phone Components.......................................................................................................4

Phone Cannot Make a Call.........................................................................................5

Transmitter Troubleshooting........................................................................................6

Low Tx Power............................................................................................................6

Cell Transmitter Setup ...............................................................................................7

Cell Transmitter Path ...............................................................................................10

Tx AGC Tuning.....................................................................................................13

Cell Power Amplifier...............................................................................................14

Cell PMIC ................................................................................................................15

Cell IF/RF AGC and PA Control.............................................................................17

Cell Power Detector .................................................................................................17

Tx System Block Diagram.......................................................................................19

Receiver Troubleshooting...........................................................................................19

Rx IF.........................................................................................................................19

Switching the Gain...................................................................................................24

Rx RF .......................................................................................................................26

Rx AGC (Cell mode)................................................................................................28

Receiver Block Diagram..........................................................................................29

Synthesizer Troubleshooting......................................................................................29

Synthesizer Setup.....................................................................................................30

VCTCXO Tuning.....................................................................................................31

VCTCXO Reference Clock......................................................................................35

UHF Synthesizer......................................................................................................36

Rx VHF....................................................................................................................38

Tx VHF ....................................................................................................................39

Tuning Descriptions....................................................................................................41

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CCS Technical Documentation Troubleshooting - RF

RF Troubleshooting

RH-48 General Troubleshooting Notes

First check the RX AGC PDM value when troubleshooting the receiver. The AGC value

should be close to the typical values in the tables. 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 but there is still a problem, check

the actual AGC voltages. RF probing at specific locations in the chain can help to pin-

point the source of the problem.

Likewise, first check the measured output power and AGC values when troubleshooting

the transmitter, which give an indication of where to start probing.

Although the tables in this chapter include power levels for many combinations of AGC

values, it is generally only necessary to check one combination. The additional informa-

tion is provided for use in unexpected situations. Likewise, although probing points and

signal-level information are given for each point in the receiver and transmitter chains, it

is not necessary 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 may be used (make sure the probe is high-imped-

ance so the measurement does not load the circuit), but they may have different gains.

Therefore, adjust the absolute measurements accordingly, especially if you are using a

probe attenuator.

Typically, the higher loss occurs at the band edges where a range is given for loss. Prob-

ing is not a very accurate method to measure absolute power; therefore, you cannot

expect measured results to exactly match the numbers listed.

Power depends on the impedance of the circuit. For example, if a filter has a nominal loss

of 5 dB, straightforward probing on the input and output and then subtracting might not

result in 5 dB because the input impedance could be different from the output imped-

ance. Most components in the RF section have the same input and output impedance

(50ohms). Where this is not the case, absolute power is noted in the tables in dBm rather

than loss or gain in dB.

Inject a CW tone into the receiver when testing the CDMA receiver. The gains and losses

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

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

RH-48

Troubleshooting - RF CCS Technical Documentation

Phone Components

Figures 1 and 2 illustrate the main components of the RH-48.

RF Connector

LCD Module Connector

Figure 1: RH-48 RF components

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CCS Technical Documentation Troubleshooting - RF

Cell Duplexer

Cell Isolator

PA PMIC DC-DC Converter

Cell Tx PA

Battery Converter

YODA Rx DownConverter

Rx IF CDMA Filter

On/Off Switch

Rx IC “Alfred” LNA+Downconverter

Cell Rx RF SAW Filter

Cell Tx SAW Filter

Jedi Tx Up-Converter

VCO

VCTCXO

UPP (B.B)UEM (B.B)

SIM Card Connector

Phone Cannot Make a Call

Verify the following if the phone cannot make a call:

• The phone is in normal mode (i.e., the phone is searching for a signal, net server is on).

• The Preferred Roaming List (PRL) is loaded into the phone.

Flash

Tomahawk Connector

Figure 2: RH-48 RF components

• The phone is tuned and has passed tuning. (Read the tuning parameters using the Batch Tune component in Phoenix; an untuned phone has all zeros in the tuning file.)

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

RH-48

Troubleshooting - RF CCS Technical Documentation

• The SID is correct and entered into the phone.

• The MIN and MDN are entered into the phone.

• The VCTCXO is centered as described in the VCTCXO tuning description on page 31.

• The transmitter and receiver are working properly in Local Mode.

Transmitter Troubleshooting

Low Tx Power

Use Phoenix to turn on the transmitter in local mode, and check the following:

1 Verify the current (0.7 - 1A for max power, mode, and channel dependent).

2 Use a microscope to visually inspect the PWB for proper placement, rotation, and

soldering of components.

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

quency:

• If the signal is not on frequency, check in the 100 MHz span.

• If the signal is present but off frequency, check the synthesizer. Most likely, one of the synthesizers is not locked, or the VCO has no output signal.

• If the signal is not present, or is present but low in amplitude, use the probing

tables to determine where in the chain the fault occurs.

4 Verify that the AGC PDMs are set for the desired Tx power as listed in the Tx AGC

Tuning table on page 12, and ensure that the AGC voltages are correct.

5 Check the LOs for proper frequency and amplitude.

6 Ensure that the power supplies to the transmitter have the correct voltage.

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CCS Technical Documentation Troubleshooting - RF

Cell Transmitter Setup

Use the following steps to set up the phone for Tx troubleshooting in Phoenix.

1Open the Phone Control dialog box.

Figure 3: Phone Control dialog box for Tx troubleshooting

2 Click the LOCAL button in the Phone State area to put the phone into Local

Mode.

3 Select the following values on the RF Main Mode dialog box:

• Band = Cell (CDMA)

• Channel = 384

• Mode = Rx/Tx

Figure 4: RF Main Mode dialog box for Tx troubleshooting

RH-48

Troubleshooting - RF CCS Technical Documentation

4 Click the Set button.

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

5 Select the Rho ON check box on the CDMA Control dialog box.

Figure 5: CDMA Control dialog box for Tx troubleshooting

6 Click the Execute button.

7 At this point you should be able to measure Tx Pout at the RF connector. The cell

band Tx Pout =0 to 2dBm. If you do not see these values, set the AGC PDM for 25dBm and probe the Tx path to figure out where in the path the fault occurs.

8Open the General I/O dialog box to set the PA gain state.

RH-48

CCS Technical Documentation Troubleshooting - RF

9 Enter 10, 13, 12, and 8 in the PIN # fields.

Figure 6: General I/O dialog box for Tx troubleshooting

10 Select the boxes in the Enable column for each pin.

11 Click the Get All button.

12 Ensure that all of the pins have a value of H in the State column. (Click the L val-

ues to change them to H values.)

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

• Tx IF AGC = -280

• Tx RF AGC = -280

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Troubleshooting - RF CCS Technical Documentation

Figure 7: RF PDM dialog box for Tx troubleshooting

14 Ensure that the Phone Tx Pout = +25dBm and the current = 770-860mA.

Cell Transmitter Path

The following table indicates the test points to probe when troubleshooting the cell transmitter path. It is recommended that you follow the steps in order. An HP high frequency probe was used to make the frequency and output power measurements.

Cell Transmitter Test Path

Test Point

T1 Z601 pin1 Jedi-Out -43dBm/

T2 Z601 pin 3 PA-In -25dBm/

T3 N803 pin 8 PA-Out 5.0dBm/

T4 Z803T Iso-Out 2.2dBm/

Part* Function

Typical Value/ Frequency HP85024A

836.52MHz

Typical Value Frequency Prod Probe

-13.2dBm/

836.52MHz

-15.4dBm/

836.52MHz

18.3dBm/

836.52MHz

10.3dBm/

836.52MHz

Comments

Output of Jedi Driver, Input to Tx SAW Filter

Output of Tx SAW, Input to PA

Output of PA, Input to Isolator

Output of Isolator, Input to Duplexer

T5 C603L IF-Out -29dBm/

228.6MHz

T6 C638T, C654T,

C633R, C635R, C603LR

T7 C655R VR7 2.7V dc UHF PLL Supply from UEM

VR5 2.7V dc VHF VCO/PLL, IQ modulator sup-

-24dBm/

228.6MHz

Tx IF Probing Point at IF Filter

ply from UEM

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CCS Technical Documentation Troubleshooting - RF

Cell Transmitter Test Path

Test Point

T8 C636L, C624T,

T9 C605R, C606R VAGC-Tx 0.2 to 1.8V dc Tx AGC Control Voltage from UPP.

T10 C658R, C600T VIO-Tx 1.8V dc Supply for Digital circuits from

T11 C805B, C810T,

T12 C802L, C813L VPA 3.6V dc

T13 C814R C814R 1.8V dc

Part* Function

VR2 2.7V dc Mixer, driver, and IF supply from L609B, C612L, C630B, L607B

VBAT 3.6V dc Battery Voltage C816R

* The R, L, T, and B values at the end of the part names indicate the Right, Left, Top, and Bottom side of the part respectively in Figures 8 and 9.

Typical Value/ Frequency HP85024A

(High Gain)

(Enable)

Typical Value Frequency Prod Probe

Comments

UEM

0.2V = Max Gain

1.8V = Min Gain

UEM

(Nominal Voltage 3.6V dc)

Main PA Supply Voltage from PMIC. Lgain=0.8V, Mgain=-1.25V, Hgain=Vbat

PA Gate Voltage (Enable/Disable) Disable=0V

RH-48

Troubleshooting - RF CCS Technical Documentation

Figure 8 shows each testing point from the Cell Transmitter Test Path table for the Jedi TXIC section. Always attach a 20dB pad (11881-60001) when probing with an HP85024A high frequency probe.

Figure 8: (Top) PWB. (Bottom left) A zoomed view of the testing points on the Jedi TXIC section.

(Bottom right) A zoomed view of the Jedi TXIC section with part numbers.

RH-48

CCS Technical Documentation Troubleshooting - RF

Figure 9 shows each testing point for the PA section from the Cell Transmitter Test Path table on page 10. Always attach a 20dB pad (11881-60001) when probing with an HP85024A high frequency probe.

Figure 9: (Top) PWB. (Bottom left) A zoomed view of the testing points on the PA section.

Tx AGC Tuning

Tx power versus IF/RF PDM can be verified against FlaLi specification limits. Make sure that the PA is set in high gain mode (GenIO bits 10, 13, and 12 are set to H).

(Bottom right) A zoomed view of the PA section with part numbers.

Tx AGC Tuning

Tx Tuning AGC Step

Tx AGC (0) 308 -46 -55 -37

Tx AGC (1) 130 -24 -34 -14

Tx AGC (2) 85 -15 -25 -6

Tx AGC (3) 51 -4.5 -14 5

Tx AGC (4) 19 2.5 -7 12

Tx AGC (5) -5 6 -3 15

Tx AGC PDM Value

Target Power

Low Limit High Limit

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Troubleshooting - RF CCS Technical Documentation

Tx AGC Tuning

Tx Tuning AGC Step

Tx AGC (6) -94 15 6 24

Tx AGC (7)* -280* 25 21 27

Cell Power Amplifier

The power amplifier (PA) has the DC/DC converter (PMIC device), which controls the transmitter. The following tables show the circuits that have an effect on the transmitter path and how to troubleshoot them.

PA Power and Gain Specifications

Mode Name

Tx AGC PDM Value

PA Power and Gain Measurements

Power Amplifier Input

Test Point

pin3-Z601 left-R814

Power Output Range

Target Power

Low Limit High Limit

Power Amplifier Output Test Point

Nominal Gain

Vcc Range

Vcc Test Point

Gain mode 0 V0 up to 6 23.8 0.75- 0.88 C806

Gain mode 1 V1 6 to 11 25.2 1.125- 1.375 C806

Gain mode 3 V2 Not used Not used 2 - 2.5 C806

Gain mode 2 Bypass 11 up 29 3 - 4 C806

Overall Gain V0 to

Bypass

unit N/A dBm dB VDC N/A

Phoenix Control and Example Values

PA Gain Step

Gen IO 12 GenIO13

LL0.8V0

H L 1.2 V1

L H 2.2 V2

HH3.7Bypass

63.5 to 7.3 +/- 0.5

PA Vcc volt (v)

Spec Name

*Not an actual FlaLi tuning PDM. PDM to produce approximately 25dBm at antenna connector.

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