Nokia 6235 User manual

Nokia Customer Care
6235/6235i/6236i (RM-60)
Mobile Terminals
Issue 1 04/2005 Company Confidential ©2005 Nokia Corporation
RF Description and
Troubleshooting

6235/6235i/6236i (RM-60)
RF Description and Troubleshooting
Page 2 ©2005 Nokia Corporation Company Confidential Issue 1 04/2005
Contents Page
6235/6235i/6236i Mobile Terminal .......................................................................................................... 5
RF Components ............................................................................................................................................... 6
Preliminary RF Troubleshooting.................................................................................................................. 7
RF Troubleshooting Equipment List........................................................................................................... 7
Transmitter RF Troubleshooting ................................................................................................................. 8
Transmitter Block Diagram .......................................................................................................................8
Transmitter Schematics .............................................................................................................................9
Transmitter Troubleshooting Guidelines .............................................................................................10
Transmitter Troubleshooting Setup ......................................................................................................10
AMPS Tx Setup ....................................................................................................................................... 11
Cell Tx Setup ........................................................................................................................................... 14
PCS Setup................................................................................................................................................. 16
Transmitter RF Troubleshooting Procedures ......................................................................................18
Failed Test: Tx PA Detector .....................................................................................................................19
Transmitter Output Spectrum ................................................................................................................20
Transmitter Test Points ............................................................................................................................21
Tx RF Part Diagram................................................................................................................................ 21
Tx DC Test Points ................................................................................................................................... 22
Tx RF Test Points .................................................................................................................................... 23
Tx DC Power Supply Test Points ........................................................................................................ 24
Transmitter UHF LO ...................................................................................................................................25
Tx UHF LO Schematic............................................................................................................................ 25
Tx UHF LO (N7000) Test Points.......................................................................................................... 26
PCS Tx UHF Spectrum Output ................................................................................................................26
Cell Tx UHF Spectrum Output ................................................................................................................27
Receiver RF Troubleshooting .................................................................................................................... 28
Receiver Block Diagram ...........................................................................................................................29
Receiver Schematics .................................................................................................................................29
RF AGC Status ............................................................................................................................................30
Turning on the Rx Path ............................................................................................................................31
Switching the Rx Gain States ................................................................................................................33
Checking AMPS from RF to IQ ........................................................................................................... 33
Checking Cell Receiver from RF to IQ.............................................................................................. 34
Checking PCS Receiver from RF to IQ.............................................................................................. 36
Receiver Diagnostic Signal Tracing ......................................................................................................37
Receiver DC Test Points........................................................................................................................ 38
Receiver RF Test Points ........................................................................................................................ 39
Receiver IF Test Points.......................................................................................................................... 40
Receiver Logic Input Voltages ................................................................................................................41
N7160 Receiver Overview .......................................................................................................................41
Synthesizer Troubleshooting .................................................................................................................... 43
Synthesizer Block Diagram .....................................................................................................................44
Synthesizer Schematics ...........................................................................................................................45
Synthesizer Troubleshooting Setup ......................................................................................................46
Top Level Troubleshooting ......................................................................................................................46
Incorrect PLL Frequencies .......................................................................................................................47
VCTCXO Troubleshooting .........................................................................................................................48

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VCTCXO Manual Tuning ...........................................................................................................................48
AFC Voltage Troubleshooting .................................................................................................................49
UHF Synthesizer Schematic ....................................................................................................................52
UHF Synthesizer Troubleshooting .........................................................................................................52
UHF Synthesizer Test Points ...................................................................................................................54
Typical UHF LO Spectrum Outputs .......................................................................................................54
Rx VHF LO (N7100) Schematic ..............................................................................................................56
Rx VHF LO Troubleshooting ....................................................................................................................57
Tx UHF LO (N7000) Schematic ..............................................................................................................58
Tx UHF LO (N7000) Troubleshooting ....................................................................................................59
Typical Transmitter UHF LO Spectrum Outputs ................................................................................59
GPS Troubleshooting................................................................................................................................... 60
GPS RF Block Diagram .............................................................................................................................60
GPS RF Schematic .....................................................................................................................................61
GPS Troubleshooting Setup ....................................................................................................................61
Self Test Failure...................................................................................................................................... 63
Oscillator Failure.................................................................................................................................... 63
CW Test Failure....................................................................................................................................... 63
GPS RF Troubleshooting....................................................................................................................... 63
GPS DC Test Points................................................................................................................................ 64
GPS RF Test Points................................................................................................................................. 65
FM Radio Troubleshooting ........................................................................................................................ 65
FM Radio Schematic .................................................................................................................................65
FM Radio Troubleshooting Setup ..........................................................................................................66
FM Radio Part Layouts and Probe Points ...........................................................................................66

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RF Description and Troubleshooting Nokia Customer Care
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Nokia Customer Care RF Description and Troubleshooting
6235/6235i/6236i (RM-60)
Issue 1 04/2005 ©2005 Nokia Corporation Company Confidential Page 5
6235/6235i/6236i Mobile Terminal
The 6235/6235i/6236i mobile terminal is based on tri-mode, Code Division Multiple
Access (CDMA), dual-band engine. The variants include a tri-mode that without GPS and
a tri-mode with GPS.
Figure 1: 6235/6235i/6236i mobile terminal
Note: The 6236i variant is identical to the 6235i variant, except that AMPS is not
supported in the 6236i variant.

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RF Components
Following are the components of the RF, bottom and top boards.
Figure 2: RF component layout - bottom
Figure 3: RF component layout - top

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Preliminary RF Troubleshooting
Verify the following if the mobile terminal cannot make a call:
• The mobile terminal is in Normal Mode (i.e., the mobile terminal is searching for
a signal, net server is on).
• The Preferred Roaming List (PRL) is loaded into the mobile terminal.
• 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.
• The call box channel is set for a channel in PRL.
• The SID is correct and entered into the mobile terminal.
• The VCTCXO is centered as described in the "VCTCXO Manual Tuning" section on
page 48.
• The transmitter and receiver are working properly in Local Mode. See
"Transmitter RF Troubleshooting"onpage8and "Receiver RF
Troubleshooting"onpage28 for detailed information.
RF Troubleshooting Equipment List
You will need the following equipment for RF troubleshooting:
• Computer with AMS version of Phoenix
• Agilent 8960 CDMA call box (or equivalent)
• Signal Generator
• Power Supply
• Digital Multimeter
• Diagnostic Test Jig (MJ-71)
• Spectrum Analyzer
• AMS RF Probe, AAS-10A (p/n0730306) or AAS-10B (p/n0730307)
• Oscilloscope
• RF Connectors and cables
• Optional High Impedance Probe

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Transmitter RF Troubleshooting
Transmitter Block Diagram
Following is the block diagram for the Tx RF system.
Figure 4: Transmitter system block diagram
N7000 Tx RFIC

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Transmitter Schematics
The following schematics are for general reference only. See the Schematics chapter for
detailed versions.
Figure 5: Transmitter schematic 1
Figure 6: Transmitter schematic 2
Cell Tx Filter
Tx LO lock voltage
Loop filter
PCS Tx Filter
N7000 Tx RFIC
Power Detector
Couplers
Cell PA
Diplexer
PCS PA
PCS Duplexer
Cell Duplexer

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Transmitter Troubleshooting Guidelines
Use some of the following guidelines when as you are troubleshooting.
• Always perform visual inspection of PCB under microscope to check proper
placement, rotation, and soldering of components.
• Look for presence of well-defined CDMA modulated signal on spectrum analyzer
at correct frequency. If signal is present but off frequency or shape looks
distorted, check synthesizer. Possibly, one of the synthesizers is not locked, or
VCO has no output signal. Check the synthesizers for proper frequency and
amplitude. See "Transmitter Output Spectrum" on page 20 and "Synthesizer
Troubleshooting"onpage43.
• Check that power supplies to transmitter have correct voltage See "Tx DC Test
Points"onpage22.
• If signal is very low in amplitude, check probing diagram to determine what part
of TX chain is ‘broken’. See "Tx RF Test Points"onpage23.
• CheckthatAGCPDMsproduceand adjust TX power within thep r o p e r l i m i t s .
See Figure 9 on page 13, Figure 12 on page 16, and Figure 13 on page 18.
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

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you are using:
•"AMPS Tx Setup"onpage11
•"Cell Tx Setup"onpage14
•"PCS Setup"onpage16
AMPS Tx Setup
Use the following procedures to prepare for AMPS Tx troubleshooting using Phoenix.
Note the 6236i variant does not support AMPS.
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.
5. Click the LOCAL button in the Phone State tab to put the mobile terminal into
Local Mode.
Figure 7: Phone Control dialog box
6. Open the Troubleshooting menu, point to AMPS, and click AMPS Control.

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The AMPS Control dialog box appears.
Figure 8: 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 5.
10. Select the Transmitter ON option, and click Execute.
11. Configure the spectrum analyzer using the following values:
• Center Frequency = 836.52 MHz
• Span = 100 MHz
• Amplitude = 20 dBm
• Attenuation = Auto
• BW = Auto
Table 1: RF PDM Values at Power Level 5
Description/Field Reference Value
AGC1 -59
AGC2 -512
PA Gain -200
Rx IF AGC +179
AFC -12
Pout +17dBm
Current 370mA
Pout w/AAS-10 at Ant. Conn. -8 dBm

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Figure 9: RF PDM dialog box for AMPS
12. Click Read Phone to update the values.

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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. (The bottom connector is a
USB port.)
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 7 on page 11.)
5. Open the Troubleshooting menu, point to RF, and click RF Main Mode.
The RF Main Mode dialog box appears.
Figure 10: 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 11: 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 = 100 MHz
• Amplitude = 20 dBm
• Attenuation = Auto
• BW = Auto
Table 2: RF PDM Values
Description/Field Reference Value
AGC1 0
AGC2 -512
PA Gain +114
Rx IF AGC 0
AFC 0
Pout +16dBm
Current 360mA
Do NOT select
this option

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Figure 12: 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 7 on page 11 .)
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 10 on page 14.)
Pout w/AAS-10 at Ant. Conn. -8 dBm
Table 2: RF PDM Values
Description/Field Reference Value

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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 11 on page 15.)
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 = 20 dBm
• Attenuation = Auto
• BW = Auto
Table 3: RF PDM Values
Description/Field Reference Value
AGC1 0
AGC2 -512
PA Gain +207
Rx IF AGC 0
AFC 0
Pout +8dBm
Current 300mA
Pout w/AAS-10 at Ant. Conn. -8dBm

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Figure 13: 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 VR2, VR6, and VR1B are on the transmit
system. (See "Tx DC Test Points" on page 22.)
• 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"onpage11, "Cell Tx Setup"onpage14, or "PCS Setup"onpage16.)
• If the voltages are incorrect, check the SMD around TX_AGC1 and TX_AGC2.
• 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.

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4. Use an AAS-10 RF probe to probe the Cell Tx output of the N7000.
• If there is no RF or low RF, look for SMD everywhere around the N7000.
• If the SMD is okay, replace the N7000.
5. Probe the PA input.
• If the level is low, look for an SMD issue on the Tx filter or matching
transformer (T7001 or T7002).
• Reflow or replace the filter as necessary.
6. Probe the PA output.
• If the RF is missing or low, look for Vbatt voltages and SMD issues on and
around the PA.
• If these are okay, replace the PA.
7. Probe the duplexer output.
• If the RF is missing or low, reflow or replace the duplexer.
8. Probe the coupler output.
• If the RF is missing or low, reflow or replace the coupler.
9. Probe the diplexer output.
• If the RF is missing or low, reflow or replace the diplexer.
Failed Test: Tx PA Detector
Use the following steps if you encounter a failed test for the Tx PA detector:
1. Use Phoenix to set the mobile terminal into Local Mode and activate the Tx with
default output power.
2. The output power at the RF test connector should be 15dBm +/- 4dB. If not,
follow the procedures in the "Transmitter RF Troubleshooting Procedures" section
on page 18.
3. Using a voltmeter on DC, probe the detector output at C7313. The voltmeter
should read approximately 1.4V. If not, replace N7300. (See "Tx RF Test Points"on
page 23 for test point locations and common power and voltage variations.)

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Transmitter Output Spectrum
Following is the correct output of the mobile terminal on a spectrum analyzer with
100MHz span. Note that if you are using the AAS-10 probe with the mobile terminal
connected to the call box, the amplitude should be approximately -7dBm at the antenna
test point on the top of the PWB.
Figure 14: Correct output spectrum
Following is an example of incorrect output.
Figure 15: Incorrect output spectrum