Nokia 3155 Guide

Nokia Customer Care
3155/3155i (RM-41), 3152 (RM-61)
Mobile Terminal
ISSUE 1 07/2005 Company Confidential ©2005 Nokia Corporation
RF Description and
Troubleshooting

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RF Description and Troubleshooting
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Contents Page
Mobile Terminal Components ..................................................................................................................... 5
Main PWB ......................................................................................................................................................5
Preliminary RF Troubleshooting.................................................................................................................. 8
Mobile Terminal Cannot Make a Call ....................................................................................................8
Tx Power Low ................................................................................................................................................8
Transmitter RF Troubleshooting ................................................................................................................. 9
Transmitter Block Diagram .....................................................................................................................10
Transmitter Schematics ...........................................................................................................................11
Transmitter Troubleshooting Setup ......................................................................................................13
AMPS Tx Setup ....................................................................................................................................... 13
Cell Tx Setup ........................................................................................................................................... 16
PCS Setup................................................................................................................................................. 18
Transmitter RF Troubleshooting Procedures ......................................................................................20
Failed Test: Tx PA Detector ................................................................................................................. 21
Tx Output Spectrum.............................................................................................................................. 22
Tx DC Test Points - Bottom Side ....................................................................................................... 23
Tx RF Test Points - Bottom Side........................................................................................................ 24
RF Power Supply DC Test Points - Bottom Side............................................................................ 25
Receiver RF Troubleshooting .................................................................................................................... 27
Receiver Block Diagram ...........................................................................................................................28
Receiver Schematics .................................................................................................................................29
RF AGC Status ............................................................................................................................................31
Turning on the Rx Path ............................................................................................................................32
Switching the Rx Gain States ................................................................................................................34
Checking AMPS from RF to IQ ........................................................................................................... 34
Checking Cell Receiver from RF to IQ.............................................................................................. 35
Checking PCS Receiver from RF to IQ.............................................................................................. 37
Receiver Diagnostic Signal Tracing ......................................................................................................38
Receiver DC Test Points........................................................................................................................ 39
Receiver RF Test Points ........................................................................................................................ 40
Receiver IF Test Points.......................................................................................................................... 41
Receiver Logic Input Voltages ................................................................................................................42
N7160 Receiver Overview .......................................................................................................................43
Synthesizer Troubleshooting .................................................................................................................... 45
Synthesizer Block Diagram .....................................................................................................................46
Synthesizer Schematics ...........................................................................................................................47
Synthesizer Troubleshooting Setup ......................................................................................................48
Incorrect PLL Frequencies.................................................................................................................... 48
VCTCXO Manual Tuning....................................................................................................................... 50
AFC Voltage Troubleshooting .................................................................................................................51
UHF Synthesizer .........................................................................................................................................52
UHF Synthesizer Test Points ............................................................................................................... 53
Rx VHF LO (N7100) Schematic ..............................................................................................................54
Rx VHF LO Troubleshooting ....................................................................................................................55
Tx UHF LO (N7000) Schematic ..............................................................................................................56
Tx UHF LO (N7000) Troubleshooting ....................................................................................................57
GPS Troubleshooting................................................................................................................................... 58

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GPS RF Block Diagram .............................................................................................................................58
GPS RF Schematic .....................................................................................................................................59
GPS Troubleshooting Setup ....................................................................................................................60
Self Test Failure...................................................................................................................................... 61
Oscillator Failure.................................................................................................................................... 61
CW Test Failure....................................................................................................................................... 61
GPS RF Troubleshooting....................................................................................................................... 61
GPS DC Test Points................................................................................................................................ 62
GPS RF Test Points................................................................................................................................. 64
FM Radio Troubleshooting ........................................................................................................................ 65
FM Radio Schematic .................................................................................................................................65
FM Radio Troubleshooting Setup .......................................................................................................66

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Mobile Terminal Components
The mobile terminal includes two PWB boards, the main PWB and the UI PWB.
Main PWB
Following are the components of the main PWB.
Figure 1: Main PWB component layout - top
Rx I/Q signal
test points
FM Radio

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Figure 2: Main PWB component layout - bottom
Rx IF CDMA filter
Pop Port
connector
Antenna
connector
Cell duplexer
PCS duplexer
Rx RF PCS filter
Rx RF Cell filter
N7160:
Rx front-end
VCO
N7000:
Tx Upconverter
N7100:
Rx downconverter
Synthesizer IC
PCS Tx filter
Rx IF AMPS filter
Cell Tx filter
PCS PA
Headset jack
Cell PA
Diplexer
VCTCXO
TX I/Q signal
test points

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Figure 3: UI PWB component layout - bottom
GPS 16.368 MHz TCXO
GPS ceramic antenna
GPS antenna
connector
GPS RF IC
GPS BB IC

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Preliminary RF Troubleshooting
The following sections identify steps to troubleshoot some common RF issues.
Mobile Terminal Cannot Make a Call
Verify the following 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 Read Parameters 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 the "VCTCXO Manual Tuning" section on
page 50.
7. The transmitter and receiver are working properly in Local Mode. See
"Transmitter RF Troubleshooting"onpage9and "Receiver RF
Troubleshooting"onpage27 for detailed information.
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
proper placement, rotation, and soldering of components.
3. Look for the presence of a Tx signal on a spectrum analyzer at the correct
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. (See "Tx
RF Test Points - Bottom Side"onpage24.)
4. Ensure that the power supplies to the Tx have the correct voltage. (See "Tx DC
Test Points - Bottom Side" on page 23)
5. Ensure that the AGC PDMs are set for the desired Tx power and that the AGC
voltages are correct. (See "AMPS Tx Setup"onpage13, "Cell Tx
Setup"onpage16, or "PCS Setup"onpage18.)

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Transmitter RF Troubleshooting
Following are the main Tx RF components.
Figure 4: Main transmitter RF components
PCS PA
Cell PA
Cell Tx SAW filter PCS Tx SAW filter Antenna Connector
Cell Duplexer Power DetectorPCS Duplexer
Power Detector N7300 Cell Coupler DC-DCPCS Coupler Diplexer
TX IQ in ~ 1.2V

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Transmitter Block Diagram
Following is the block diagram for the Tx RF system.
Figure 5: Tx system block diagram
Div4
A
ntenna
Diff/Sngl
Ph
one
t
es
t
Connector
TiKu GENIO
Div
2
Cell PA
PLL
Pwr Det
PcsPA
Diff/Sngl
Vbat
Iref
Iref
Cell Duplexe
r
PCSDuplexer
Couple
r
Couple
r
Txagc1
19.2MHz
IDCout
ITemp
Diplexer
IP
IN
QP
QN
PaBias
PwrOut
TXGate
Vbat
A
GC
A
GC
A
GC
A
GC
VccPa
VccPa Dc-Dc
Vbat
PaDcDc
VccPa
N7000 Tx IC

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Transmitter Schematics
The following schematics are for general reference only. See the Schematics chapter for detailed versions.
Figure 6: Transmitter schematic 1
N7000 Tx IC
Tx LO lock
voltage
Loop filter
Cell Tx filter
PCS Tx filter

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Figure 7: Transmitter schematic 2
PCS duplexer
Diplexer
Couplers
PCS PA
Cell PA
Cell duplexer
Power detector
DC-DC

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Transmitter Troubleshooting Setup
Use the following sets of procedures to troubleshoot the transmitter using Phoenix. Due
to the compact layout of the mobile terminal, some of the major test points are not
accessible without destroying the shield frames and the EL lamp. For example, duplexers/
diplexer/couplers test points are blocked by the test jig, the PA test points are
underneath the shield frame, and the BBIQ points are underneath the EL lamp.
To minimize effort, check the following in order:
1. Tx power at the RF connector.
2. All Tx DC points.
3. All soldering jig points for the whole Tx chain.
4. UHF LO presence:
• If the UHF LO is present, check the N7000 output.
• If the UHF LO is not present, it is a synthesizer problem.
5. If there is no N7000 output:
a. Change the N7000.
b. If the problem persists, reflow the duplexers, diplexer, and couplers.
c. If the problem persists, change the PA.
6. If there are several failed mobile terminals with the same symptoms, it may be
necessary to break one to determine the cause.
Use the following sections to set up troubleshooting in Phoenix according to the band
you are using:
•"AMPS Tx Setup"onpage13
•"Cell Tx Setup"onpage16
•"PCS Setup"onpage18
AMPS Tx Setup
Use the following procedures to prepare for AMPS Tx troubleshooting using Phoenix.
1. Connect the RF test connector to a spectrum analyzer.
2. Connect the mobile terminal to the PC via a test jig. (The bottom connector is a
USB port.)
3. Connect a power supply to the mobile terminal.
4. Open the Troubleshooting menu, and click Phone Control.
The Phone Control dialog box appears.

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5. Click the LOCAL button in the Phone State area to put the mobile terminal into
Local Mode.
Figure 8: Phone Control dialog box
6. Open the Troubleshooting menu, point to AMPS, and click AMPS Control.
The AMPS Control dialog box appears.
Figure 9: AMPS Control dialog box
7. Click the Tx Control tab.
8. In the Set Channel field, type 384.
9. In the Power Level field, type 2.
10. Select the Transmitter ON option, and click Execute.

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11. Configure the spectrum analyzer using the following values:
• Center Frequency = 836.52 MHz
• Span = 100 MHz
• Amplitude = 30 dBm
• Attenuation = Auto
• BW = Auto
Figure 10: RF PDM dialog box for AMPS
12. Click Read Phone to update the values.
Table 1: RF PDM Values at Power Level 2
Description/Field Reference Value
AGC1 50
AGC2 -31
AGC3 -400
Rx IF AGC 0
AFC 0
Pout at RF connector +14dBm
Current 400-500mA

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Cell Tx Setup
Use the following procedures to prepare for Cell Tx troubleshooting using Phoenix.
1. Connect an RF test connector to a call box.
2. Connect the mobile terminal to the PC via a test jig.
3. Connect a power supply to the mobile terminal.
4. On the Phone Control dialog box, click the LOCAL button in the Phone State
area to put the mobile terminal into Local Mode. (See Figure 8 on page 14.)
5. Open the Troubleshooting menu, point to RF, and click RF Main Mode.
The RF Main Mode dialog box appears.
Figure 11: RF Main Mode dialog box for Cell Mode
6. Select the following values on the RF Main Mode dialog box:
•Band = Cell (CDMA)
•Channel = 384
•Mode = Rx/Tx
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.

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The CDMA Control dialog box appears.
Figure 12: CDMA Control dialog box for Cell Tx troubleshooting
9. Select the following values:
•State = Rho ON
•Band = Cell
•Radio Configuration = Mode 1: IS-95 Voice
Note: Do NOT select the Set default PDM values option
10. Click Execute.
11. Configure the spectrum analyzer using the following values:
• Center Frequency = 836.52 MHz
• Span = 5MHz
• Amplitude = 0 dBm
• Attenuation = Auto
• BW = Auto
•VIDAVG=10
Table 2: RF PDM Values
Description/Field Reference Value
AGC1 50
PA_Bias 128
PA_DC_DC 100
Pout at RF connector -28dBm peak
Current 240mA typ
Do NOT select
this option

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Figure 13: RF PDM Control dialog box for Cell band
12. Click Read Phone to update the values.
PCS Setup
Use the following procedures to prepare for PCS Tx troubleshooting using Phoenix.
1. Connect an RF test connector to a call box.
2. Connect the mobile terminal to the PC via a test jig. (The bottom connector is a
USB port.)
3. Connect a power supply to the mobile terminal.
4. Open the Troubleshooting menu, and point to Phone Control.
The Phone Control dialog box appears. (See Figure 8 on page 14.)
5. Click the LOCAL button in the Phone State area to put the mobile terminal into
Local Mode.
6. Open the Troubleshooting menu, point to RF, and click RF Main Mode.
The RF Main Mode dialog box appears. (See Figure 11 on page 16.)

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7. Select the following values on the RF Main Mode dialog box:
•Band = PCS (CDMA)
•Channel = 600
•Mode = Rx/Tx
8. Click Set.
Note: Be sure that the “RF Main Mode set successfully” message appears in
the status bar.
9. Open the Troubleshooting menu, point to RF, and click CDMA Control.
The CDMA Control dialog box appears. (See Figure 12 on page 17.)
10. Select the following values on the CDMA Control dialog box.
•State = Rho ON
•Band = PCS
•Radio Configuration = Mode 1: IS-95 Voice
Note: Do NOT select the Set default PDM values option.
11. Click Execute.
12. Open the Troubleshooting menu, point to RF, and click PDM Control.
13. Configure the spectrum analyzer using the following values:
• Center Frequency = 1880 MHz
• Span = 100 MHz
• Amplitude = 0 dBm
• Attenuation = Auto
• BW = Auto
•VIDAVG=10
Table 3: RF PDM Values
Description/Field Reference Value
AGC1 50
PA_Bias 128
PA_DC_DC 100
Pout at RF connector -35dBm peak
Current 250mA typ

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Figure 14: RF PDM Control dialog box for PCS band
14. Click Read Phone to update the values.
Transmitter RF Troubleshooting Procedures
After Phoenix is set up using either the AMPS, Cell, or PCS setup procedures, use the
following steps to troubleshoot the transmitter.
1. Using a voltmeter, check to see that all VIO, VR2, VR6, and VR1B are on the
transmit system. (See "Tx DC Test Points - Bottom Side"onpage23.)
• If any are missing, look for SMD problems around the N7000 and the UEME.
• If SMD is good, replace the UEME.
2. Once all DC voltages are present, check the AGC control voltages. (See "AMPS Tx
Setup"onpage13, "Cell Tx Setup"onpage16, or "PCS Setup"onpage18.)
• If the voltages are incorrect, check the SMD around TX_AGC1.
• If the SMDs are correct, replace the D2800.
3. Using an oscilloscope, check the input modulation BBIQ wave forms at R7021,
R7022, R7023, and R7024. They should all be present with an AC swing of about
500mVpp, with an offset of +1.2V.
• If one or more waveforms are missing, look for SMD problems around these
resistors.
• If the SMD is good, replace the UEM.