Nokia Customer Care 6235/6235i/6236i (RM-60) Mobile Terminals RF Description and Troubleshooting Issue 1 04/2005 Company Confidential ©2005 Nokia Corporation
6235/6235i/6236i (RM-60) RF Description and Troubleshooting Contents Page 6235/6235i/6236i Mobile Terminal .......................................................................................................... 5 RF Components ............................................................................................................................................... 6 Preliminary RF Troubleshooting.......................................................................................................
Nokia Customer Care 6235/6235i/6236i (RM-60) RF Description and Troubleshooting VCTCXO Manual Tuning ...........................................................................................................................48 AFC Voltage Troubleshooting .................................................................................................................49 UHF Synthesizer Schematic .................................................................................................................
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6235/6235i/6236i (RM-60) RF Description and Troubleshooting Nokia Customer Care 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.
235/6235i/6236i (RM-60) RF Description and Troubleshooting RF Components Following are the components of the RF, bottom and top boards.
6235/6235i/6236i (RM-60) RF Description and Troubleshooting Nokia Customer Care 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.
6235/6235i/6236i (RM-60) RF Description and Troubleshooting Transmitter RF Troubleshooting Transmitter Block Diagram Following is the block diagram for the Tx RF system.
6235/6235i/6236i (RM-60) RF Description and Troubleshooting Nokia Customer Care Transmitter Schematics The following schematics are for general reference only. See the Schematics chapter for detailed versions.
6235/6235i/6236i (RM-60) RF Description and Troubleshooting 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.
6235/6235i/6236i (RM-60) RF Description and Troubleshooting Nokia Customer Care you are using: • "AMPS Tx Setup" on page 11 • "Cell Tx Setup" on page 14 • "PCS Setup" on page 16 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.
6235/6235i/6236i (RM-60) RF Description and Troubleshooting 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.
6235/6235i/6236i (RM-60) RF Description and Troubleshooting Nokia Customer Care Figure 9: RF PDM dialog box for AMPS 12. Click Read Phone to update the values.
6235/6235i/6236i (RM-60) RF Description and Troubleshooting 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.
6235/6235i/6236i (RM-60) RF Description and Troubleshooting Nokia Customer Care The CDMA Control dialog box appears. Do NOT select this option 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.
6235/6235i/6236i (RM-60) RF Description and Troubleshooting Table 2: RF PDM Values Description/Field Reference Value Pout w/AAS-10 at Ant. Conn. -8 dBm 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.
6235/6235i/6236i (RM-60) RF Description and Troubleshooting Nokia Customer Care 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.
6235/6235i/6236i (RM-60) RF Description and Troubleshooting 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.
6235/6235i/6236i (RM-60) RF Description and Troubleshooting Nokia Customer Care 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.
6235/6235i/6236i (RM-60) RF Description and Troubleshooting 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.
Nokia Customer Care 6235/6235i/6236i (RM-60) RF Description and Troubleshooting Transmitter Test Points Tx RF Part Diagram Following are the transmitter parts located on the bottom side of the main PWB.
6235/6235i/6236i (RM-60) RF Description and Troubleshooting Tx DC Test Points Following are the Tx DC test points located on the bottom side of the main PWB.
Nokia Customer Care 6235/6235i/6236i (RM-60) RF Description and Troubleshooting Tx RF Test Points Figure 18 shows the Tx RF test points located on the bottom side of the main PWB.
6235/6235i/6236i (RM-60) RF Description and Troubleshooting Tx DC Power Supply Test Points Following are the RF power supply DC test points located on the bottom side of the main PWB.
6235/6235i/6236i (RM-60) RF Description and Troubleshooting Nokia Customer Care Transmitter UHF LO Tx UHF LO Schematic There are two fixed LOs; 3296.16~3395.88MHz for cell band and 3700~3819.90MHz for PCS band. This is the first LO for up-conversion. Refer to frequency plan. Monitor control voltage at C7014. At this control voltage the N7000 LO is locked, should be between 1.2 and 1.8VDC.
6235/6235i/6236i (RM-60) RF Description and Troubleshooting Tx UHF LO (N7000) Test Points Figure 21: UHF LO (N7000) Block Diagram PCS Tx UHF Spectrum Output For PCS analysis of the UHF LO, configure the spectrum analyzer using the following values (see Figure 22): Page 26 • Center Frequency = 1880 MHz • Span = 200 MHz • RBW = 300 Hz • VBW = 300 Hz ©2005 Nokia Corporation Company Confidential Issue 1 04/2005
6235/6235i/6236i (RM-60) RF Description and Troubleshooting Nokia Customer Care Key Observation 50 kHz offset —59dBC Figure 22: PCS Tx UHF LO Sprectum Output Cell Tx UHF Spectrum Output For Cell analysis of the UHF LO, configure the spectrum analyzer using the following values (see Figure 22): • Center Frequency = 836.
6235/6235i/6236i (RM-60) RF Description and Troubleshooting Key Observation 30 kHz offset —65dBC Figure 23: Cell Tx UHF LO Sprectum Output Receiver RF Troubleshooting The heart of the receiver is the N7160 Rx IC, which contains two LNAs and mixers. The other components are passive. There are two RF SAW filters for the Cell and PCS bands. In addition, there are two additional IF filters, an IF SAW for CDMA and an IF Crystal for AMPS.
6235/6235i/6236i (RM-60) RF Description and Troubleshooting Nokia Customer Care Receiver Block Diagram Following is the receiver system block diagram. Figure 24: Receiver system block diagram Receiver Schematics The main part of the receiver is the N7160 Rx IC. This Rx IC contains two LNA and mixers. The rest of the components are passive. The following schematics are for general reference only. See the Schematics chapter for detailed versions.
6235/6235i/6236i (RM-60) RF Description and Troubleshooting The back-end of the receiver consists of the N7100 IC. VGA and IQ Demodulator are the main functions. Loop filter Rx LO lock voltage 1.2 to 1.7 Vdc N7100 Rx downconverter Figure 26: Receiver schematic - 2 RF AGC Status When configuring the values on the RF AGC Status dialog box, note the following: Page 30 • The RF AGC status functionality only works in Call Mode.
6235/6235i/6236i (RM-60) RF Description and Troubleshooting Nokia Customer Care • Clicking the Stop Updating button allows you to toggle between the Update Every 2 Seconds and Stop Updating functions. LNA Gain (High[Boost for PCS]/Low) Rx IF AGC PDM settings BBAMP Gain Settings AFC PDM settings PA AGC PDM settings Tx AGC 2 PDM settings Tx AGC 1 PDM settings Figure 27: RF AGC Status dialog box Turning on the Rx Path Use the following steps to turn on the Rx path using Phoenix. 1.
6235/6235i/6236i (RM-60) RF Description and Troubleshooting 2. Click the Execute button. 3. Depending on the band, use the applicable settings from the table below on the RF Main Mode dialog box. Table 4: RF Main Mode Dialog Box Settings Band Mode Channel AMPS Rx = 881.52 MHz 384 Cell Rx = 881.
6235/6235i/6236i (RM-60) RF Description and Troubleshooting Nokia Customer Care Switching the Rx Gain States Use the RF Gen I/O dialog box to switch the gain state (Hi and Lo) for CDMA and AMPS modes. High Gain State (default) Cell AMPS Low Gain State PCS CDMA Figure 30: RF Gen I/O dialog box Checking AMPS from RF to IQ Use the following steps to check the AMPS receiver functionality from RF to IQ output. 1. Start Phoenix in Local Mode with only the Rx path turned on. 2.
6235/6235i/6236i (RM-60) RF Description and Troubleshooting Figure 31: Receiver IQ Level on AMPS band Figure 32 shows the AMPS spectrum and the test points located on the top side of the main PWB. All four test points should be approximately equal. WARNING: Direct current is present on these test points.
6235/6235i/6236i (RM-60) RF Description and Troubleshooting Nokia Customer Care 3. Measure a 300kHz tone on the analyzer. You should see a typical -21dBm IQ tone for CDMA Cell. dBm Cell I Q Output Trace A 1 0 -10 Trace A 302 kHz -21.2500 dBm 1 -20 -30 -40 -50 -60 -70 -80 -90 -100 Centre: 300 kHz Res BW: 3 kHz 5/5/2004 3:29:30 PM Atten: 10 dB Vid BW: 3 kHz CellIQ.
6235/6235i/6236i (RM-60) RF Description and Troubleshooting Checking PCS Receiver from RF to IQ Use the following values to check the PCS receiver functionality from RF to IQ output. 1. Start Phoenix in Local Mode with only the Rx path turned on. 2. Inject a –75dBm CW signal of 1960.5MHz (i.e. 500kHz offset from 1960MHz or 10 channels away). 3. Measure a 500kHz tone on the analyzer. (If a 300kHz tone works but a 500kHz tone does not, the problem is in the BB filter, possibly not set by Phoenix.
6235/6235i/6236i (RM-60) RF Description and Troubleshooting Nokia Customer Care Rx_QP Rx_QN Rx_IP Rx_IN Figure 36: PCS spectrum and the test points on the top side of the main PWB Receiver Diagnostic Signal Tracing Use the following steps to trace the receiver signal. 1. Inject an external signal source of –25dBm to the RF input. An Agilent call box 8960 is recommended. 2. Press the Call Setup button, press the Active Cell soft button, and select CW. 3.
6235/6235i/6236i (RM-60) RF Description and Troubleshooting Receiver DC Test Points Figure 37: Receiver DC troubleshooting test points on the bottom side of the main PWB Page 38 ©2005 Nokia Corporation Company Confidential Issue 1 04/2005
Nokia Customer Care 6235/6235i/6236i (RM-60) RF Description and Troubleshooting Receiver RF Test Points Figure 38: Rx RF test points on the bottom side of the main PWB Issue 1 04/2005 ©2005 Nokia Corporation Company Confidential Page 39
6235/6235i/6236i (RM-60) RF Description and Troubleshooting Receiver IF Test Points Figure 39: Receiver IF test points on the bottom side of the main PWB Page 40 ©2005 Nokia Corporation Company Confidential Issue 1 04/2005
6235/6235i/6236i (RM-60) RF Description and Troubleshooting Nokia Customer Care Receiver Logic Input Voltages Figure 40 shows the receiver logic input voltages. N7160 1 3 2 Figure 40: Receiver logic input voltage test points Table 5 includes the measure logic levels for the N7160. Table 5: Rx Front-end (N7160) Logic Levels Mode Logic Input Voltages IF_SEL BAND GAIN_CTL AMPS High Gain 2.8 V 0.1 V 2.8 V AMPS Low Gain 2.8 V 0.1 V 0V Cell CDMA High Gain 0V 0.1 V 2.
6235/6235i/6236i (RM-60) RF Description and Troubleshooting 1900MHz (PCS). • After the RFA, there is a mixer, and then the signals are separated by CDMA (Cell and PCS) and AMPS. For example, if there is no IF frequency (128.1MHz) check both Cell and PCS. If only one has 128.1MHz at L753, ensure that IF_SEL is working. If it is, then replace the N750 due to a bad RFA. If Cell and AMPS are working but PCS is not, look at the band select line and the PCS LNA before replacing the N7160.
6235/6235i/6236i (RM-60) RF Description and Troubleshooting Nokia Customer Care IMPORTANT: You must check for both conditions before replacing the chip. If you have no LO signal, refer to "UHF Synthesizer Troubleshooting" on page 52. If you have a significant supply voltage drop on one of the supply pins, then replace the N7160.
6235/6235i/6236i (RM-60) RF Description and Troubleshooting Synthesizer Block Diagram RX VHF Synthesizer N7100 Rx VHF LO 256.2MHz UHF LO 1009.62MHz (Cell ch. 384) 2088.1MHz (PCS ch. 600) UHF Synthesizer N7200 VCTCXO 19.2MHz UHF Synthesizer N7000 Tx UHF LO 3395.88MHz 3819.
6235/6235i/6236i (RM-60) RF Description and Troubleshooting Nokia Customer Care Synthesizer Schematics The following schematics are for general reference only. See the Schematics chapter for detailed versions. 19.
6235/6235i/6236i (RM-60) RF Description and Troubleshooting Synthesizer Troubleshooting Setup Use the following steps to troubleshoot the synthesizer using Phoenix: 1. On the Phone Control dialog box, click the LOCAL button in the Phone State area to put the mobile terminal into Local Mode. Figure 44: Phone Control dialog box 2. Select the following values on the RF Main Mode dialog box:.
6235/6235i/6236i (RM-60) RF Description and Troubleshooting Nokia Customer Care The level of 19.2MHz is also important because the D2800 is very sensitive and can pick up a weak 19.2MHz clock. This can result in intermittent problems, such as constant phone reset. • The synthesizers for 6235/6235i/6236i are: Table 8: Synthesizers for 6235/6235i/6236i Synthesizer Band Channel PLL Dual Band UHF Cell and AMPS 1009.62 MHz at CH384 separate LMX2310 PLL IC PCS 2088.
6235/6235i/6236i (RM-60) RF Description and Troubleshooting VCTCXO Troubleshooting Without 19.2MHz, the mobile terminal does not power up. This signal goes to the N7100, N7000, D2800, and the UHF PLL. Check the test points in Figure 45 for the presence of the 19.2MHz signal. Figure 45: VCTCXO test point output values If you do not see the VCTCXO signal at any of these points, check voltage at VR3, main supply line for VCTCXO, it should be 2.78VDC.
Nokia Customer Care 6235/6235i/6236i (RM-60) RF Description and Troubleshooting 3. On the AMPS Control dialog box, set the Set Channel field to 384, the Power Level field to 5, and select the Transmitter ON check box. (See Figure 8 on page 12 for an example of the AMPS Control dialog box.) 4. Click the Rx RFI tab, make sure the AFC Control check box is cleared, and click Execute. 5.
6235/6235i/6236i (RM-60) RF Description and Troubleshooting Figure 47 shows a partial schematic of the R7201. Figure 47: Partial schematic showing the R7201 2. Measure the DC voltage at R7201. The following typical voltages are shown in Figure 48. • 1 = AFC PDM[-1024]=0.8V • 2 = AFC PDM[0]=1.3V • 3 = AFC PDM[1023]=2.
Nokia Customer Care 6235/6235i/6236i (RM-60) RF Description and Troubleshooting Figure 49: Tx Output for PCS channel 600, power level 5 Issue 1 04/2005 ©2005 Nokia Corporation Company Confidential Page 51
6235/6235i/6236i (RM-60) RF Description and Troubleshooting UHF Synthesizer Schematic UHF PLL IC Dual-band VCO Lock voltage Loop filter components UHF Synthesizer Troubleshooting The UHF LO frequency varies with the channel and can be calculated using the Frequency Calculator dialog box in the Phoenix RF component (see Figure 50 on page 53). Use the following steps to troubleshoot the UHF LO frequency. 1. Ensure that the LO is locked.
6235/6235i/6236i (RM-60) RF Description and Troubleshooting Nokia Customer Care Figure 50: RF Frequency Calculator dialog box Issue 1 04/2005 ©2005 Nokia Corporation Company Confidential Page 53
6235/6235i/6236i (RM-60) RF Description and Troubleshooting UHF Synthesizer Test Points Figure 51: UHF synthesizer layout Typical UHF LO Spectrum Outputs When analyzing the specturm ouputs, first measure the purity of the UHF LO, then look at the level offset from the carrier. Also check the VCO, PLL IC, loop filter and power decoupling. The results in Figure 52 and Figure 53 may be difficult to accomplish without a high impedance and high spectrum analyzer.
Nokia Customer Care 6235/6235i/6236i (RM-60) RF Description and Troubleshooting Keys observations: - Clean and spur-free signal - 30kHz offset –83dBc - 50kHz offset –92dBc - 60kHz offset –91dBc - 90kHz offset –91dBc Figure 52: UHF LO Output for Cell channel 384, power level 5 Keys observations: - Clean and spur-free signal - 30kHz offset –84dBc - 50kHz offset –87dBc - 60kHz offset –85dBc - 90kHz offset –88dBc Figure 53: UHF Output for PCS channel 600, power level 5 Issue 1 04/2005 ©2005 Nokia Corpora
6235/6235i/6236i (RM-60) RF Description and Troubleshooting Rx VHF LO (N7100) Schematic Following are the main layout components on a partial view of the Rx VHF schematic. See the Schematics chapter for detailed versions.
6235/6235i/6236i (RM-60) RF Description and Troubleshooting Nokia Customer Care Rx VHF LO Troubleshooting The VHF LO operates at a fixed frequency of 256.2MHz. It is the second LO for downconversion to I and Q for baseband processing. Use the following steps to troubleshoot the VHF LO. 1. Monitor the test point at C7100. Ensure that a locked and stable 256.2MHz with amplitude ~ –60dBm is present on the spectrum analyzer (or, with a high impedance probe, ~ -2dBm at C7104). 2.
6235/6235i/6236i (RM-60) RF Description and Troubleshooting Tx UHF LO (N7000) Schematic The following partial schematic is for general reference only. See the Schematics chapter for complete detailed versions.
6235/6235i/6236i (RM-60) RF Description and Troubleshooting Nokia Customer Care Tx UHF LO (N7000) Troubleshooting There are two fixed LOs, 3296.16~3395.88MHz for cell band and 3700~3819.90MHz for PCS band. This is the only LO for up-conversion. Be sure to monitor the control voltage at R7001. When the N7000 LO is locked, this control voltage should be between 1.2 and 1.8Vdc.
6235/6235i/6236i (RM-60) RF Description and Troubleshooting Keys observations: - the following Ref Spurs - 50kHz offset –59dBc Figure 59: Transmitter UHF LO (3700~3819.
6235/6235i/6236i (RM-60) RF Description and Troubleshooting Nokia Customer Care GPS RF Schematic The following schematic is for general reference only. See the Schematics chapter for a detailed version. GPS LNA GPS TCXO GPS RF Chip RF filter 2 RF test input RF filter 1 Figure 61: GPS RF schematic GPS Troubleshooting Setup Use the following steps to set up GPS signal using Phoenix. 1.
35/6235i/6236i (RM-60) RF Description and Troubleshooting 3. Inject a -110dBm tone at 1575.52MHz at the GPS connector (X6250) with a signal generator or call box. CW Tone (X6250) Figure 62: X6250 on the bottom side of the UI PWB 4. Open the Troubleshooting menu, and click GPS Testing. The GPS Control dialog box appears. Figure 63: GPS Control dialog box 5. In the Test Mode field, ensure that Galvanic is selected. 6. Click Execute.
Nokia Customer Care 6235/6235i/6236i (RM-60) RF Description and Troubleshooting Self Test Failure If the test fails, repeat steps 1—6. If the test fails again, continue with the following selftest failure troubleshooting: 1. Verify the DC voltages at VRF_GPS and VIO_GPS. ("GPS DC Test Points" on page 64 for test point locations and values.) 2. Inspect all GPS circuit elements around the GPS BB chip (D6200). 3. If the elements pass a visual inspection, replace the D6200. Oscillator Failure 1.
6235/6235i/6236i (RM-60) RF Description and Troubleshooting 3. Inject a -50dBm tone at 1575.52MHz at the GPS connector (X6250) with a signal generator or a call box. (See Figure 62.) GPS DC Test Points Measure the following test points with an AAS-10B probe and spectrum analyzer set at center frequency 1575.25MHz (span = 500kHz), or with a voltmeter as required.
6235/6235i/6236i (RM-60) RF Description and Troubleshooting Nokia Customer Care GPS RF Test Points Figure 66: GPS RF probe points on bottom side of PWB FM Radio Troubleshooting FM Radio Schematic The following schematic is for general reference only. See the Schematics chapter for a detailed version.
6235/6235i/6236i (RM-60) RF Description and Troubleshooting FM Radio Troubleshooting Setup Use the following steps to troubleshoot the FM radio while using a Pop-port headset. 1. Connect the Pop-port headset (HDS-3) to the Pop-port connector (bottom connector). 2. Select the Menu > Media > Radio from the mobile terminal user interface. 3. In an FM radio broadcast coverage area, set a local radio channel by scanning automatically using the Automatic tuning option.
6235/6235i/6236i (RM-60) RF Description and Troubleshooting Nokia Customer Care FM Audio coupling caps FM Antenna matching components FM Radio Circuitry N6100 Figure 68: FM radio parts on the bottom side of the main PWB Issue 1 04/2005 ©2005 Nokia Corporation Company Confidential Page 67
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