Panasonic TH42PX20U - 42" HDTV PLASMA DISPLAY Service Update Information Download Page 46 | Manualshive

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Panasonic TH42PX20U - 42

Local screen failure

The Plasma Display Panel unit may develop a failure, where the symptom is
localized in a particular area of the screen. The figure below can help localize the
circuit board that is most likely to be defective. In the example in figure 24, one
of the two boards, C2 and D is likely to be the cause.

Figure 24

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Summary of Contents for TH42PX20U - 42" HDTV PLASMA DISPLAY

Page 1: ...not designed for use by the general public It does not contain warnings or cautions to advise non technical individuals of potential dangers in attempting to service a product Products powered by electricity should be serviced or repaired only by experienced professional technicians Any attempt to service or repair the product or products dealt with in this service information by anyone else could...

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Page 3: ...tal Processor 19 Main Picture 19 RGB Amplifier 21 RGB PC Select 22 D Board Outline 23 Sync Signal Process 24 SC Board Explanation 25 SS Board Explanation 28 Power Supplies GP6D Chassis 31 Standby power supply 31 VSUS High Voltage Source 32 Main Power Supply 34 VDA and other Voltage Sources 35 Protection Circuits 37 System Control Circuit 39 Panel Operations 39 TV Operations 40 Diagnostic Procedure...

Page 4: ...est Point locations 56 Serviceman mode Electronic Controls 56 Serviceman mode Electronic Controls 57 CAT computer aided test Mode 58 I2 C Mode 59 I2 C Menu Structure 60 CD mode 61 SD Mode 62 Alignment Procedures 63 Pedestal Setting 63 NTSC White Balance Adjustment 64 HD Panel White Balance Adjustment 65 Sub Brightness Setting 66 Hotel Mode Operation 67 Service Contact Information 70 4 ...

Page 5: ...th charts and connector information should provide enough detail to the technician for the accurate repair of the product Alignment and adjustment procedures are also included in this document The Block diagrams and the schematic drawings reference the model TH 42PHD5 TH 42PX20U and TH 42PA20U but the technology is consistent with any GPH5D and GP6D series Plasma display panels 5 ...

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Page 7: ... S Video Inputs 1 HDMI input Scalable PIP 1 4 to 1 16 PC SD Card Inputs Integrated Speaker System BBE sound 1080i 480p capable 720p PC input only TH 42PA20U 42 inch 106 cm SD Version 2 Component Video Inputs 3 Composite Video Inputs 3 S Video Inputs 1 DVI input Scalable PIP 1 4 to 1 16 Integrated Speaker System BBE sound 1080i 480p capable TH 37PA20U 37 inch 94cm SD Version 2 Component Video Input...

Page 8: ...um Standby Normal Standby Save On Power Off 295W 2 8W 1 5W 225W 2 8W 1 5W 265W 1 5W 0 6W 0 4W HD Models Chassis GPH5D GPH6D Panel Size 50 42 50 42 Pixels H x V 1366 x 768p 1024 x 768p 1366 x 768p 1024 x 768p Brightness Set Peak cd m2 260 250 300 360 Dark 3000 1 4000 1 Contrast 150 lux 90 1 160 1 Gradation 1024 shades 1536 shades Sharpness Good Vivid Color Temp 11000 11000 Power Consumption Maximum...

Page 9: ...A Contrast 4000 1 Dimensions W x H x D 1170 x 658 x 99 mm Weight 77 2 lb 35 0 kg HD Models Model Number TH 42PX20U P Chassis GPH6D Screen Size HD type 42 16 x 9 920 x 518 mm Number of Pixels H 1024 x 768 VGA Number of Dots H 3072 x V 768 Pixel Size W 0 90 x H 0 645 mm Panel Drive Method AC Type Sub Field Drive System Variable sub Field Power Source AC 120V 50 60 Hz Power Consumption 295W Standby P...

Page 10: ...eproduces 1 070 Million Colors DVI Input HD models Figure 1 New 5 Facet Asymmetrical Cell Structure Panel Improves Brightness Level by 45 New Real Black Drive System Achieves greater than 4000 1 Contrast Ratio in Dark Environments New Deep Black Front Glass Filter Improves Contrast Ratio in Lighting Environment by 80 Super Real Gamma System Reproduces 1 536 shades of gradation 10 bit Digital Proce...

Page 11: ...S Si in ng gl le e S Sc ca an n S SD D D Du ua al l S Sc ca an n H HD D Figure 2 High performance Higher brightness Simple and low cost circuit 42 SD PCB Board Layout Diagram Figure 2 11 ...

Page 12: ...Switching and Video Input Circuits DG Digital Core MPU RGB amp and DVI Input Circuits Board Comparison Chart GP5 Chassis GP6 Chassis Board Function C1 C1 Data Drive C2 C2 Data Drive D2 D RGB Digital Processor Format converter Plasma AI Discharge Control Circuits Sub Field Processor D1 DG Digital Core MPU RGB amp and DVI Input Circuits V1 G Front Switch PC and Video Input Circuits HX and HZ Boards ...

Page 13: ... I2 C Bus SDA SCL These two outputs are then connected to the main switch IC The panel also contains three component inputs and a DVI or HDMI input depending upon the model that are connected to the main switch The DVI or HDMI input connector connected to the DG Board outputs the digital signal to the DVI or HDMI receiver where it undergoes serial to parallel conversion The output of the receiver ...

Page 14: ... Main CPU It generates the On Screen Display OSD RGB signals which also enters the RGB amplifier stage A switching circuit combines the two sets of RGB signals for display on the screen All NTSC Component and RGB picture adjustments such as picture tint color brightness etc are performed inside this IC The RGB PC select circuit switches between PC and all other inputs The output of the switch is r...

Page 15: ...eo signals produced by the main tuner tuner 1 and sub tuner tuner 2 are applied to the H Board via pin 1 of the connector T11 H11 and pin 1 of the connector T21 H21 The signal applied to the AV3 video input located at the bottom of the front panel enters the G Board and passes through to the DG Board without alteration It is then applied to the H Board IC4301 on the H Board selects the main video ...

Page 16: ...receiver is converted to a Y Pb and Pr component signal and then applied to pins 14 16 and 18 of IC4302 via pins 415 116 and 316 of connector H1 DG1 IC4302 selects between NTSC Component and DVI video input signals The selected signals can be in any of the three formats Video Y C or Y Pb Pr The main signal is output via pins 43 44 and 46 of IC4302 The signals are amplified and output to the DG Boa...

Page 17: ...layer or other digital devices IC5001 converts the digital video to parallel analog RGB video The HDCP High bandwidth digital content protection circuit monitors the DVI signal for copyright protection The output of IC5001 is then applied to IC5102 The EDID EEPROM allows for external control of the picture from the DVI source 17 ...

Page 18: ...e vertical and horizontal sync pulses of the DVI receiver to convert the analog RGB signal to Y Pb Pr component signal The signal is now in the form of an ATSC signal format that can be processed like any other component signal The output is sent to the Main switch IC4302 for selection 18 ...

Page 19: ...a demodulator circuit that separates the color signal into Pb and Pr data If the incoming video is in the 480p and 1080i format the main Y signal is converted to digital by IC4515 before being applied to IC4501 The A D converter inside IC4501 converts the color signals to digital The data of the color signals bypass the comb filter and Chroma demodulator circuits to join up with the luminance data...

Page 20: ...ilter where luminance and chrominance are separated IC4502 processes the Sub video data for use in the PIP mode In this mode the main and sub video components are combined into one set of Y Pb and Pr component signals The line doubler located inside the IC halves the horizontal line period doubling the horizontal frequency to 31 468KHz Using IC4518 as a temporary storage area IC4502 then converts ...

Page 21: ...n MPU IC001 enter the RGB amplifier IC4512 A switching circuit combines the two RGB signals for display on the screen The Adjust Data section sets the RGB level matching the required levels for the DG board The output of IC4512 enters IC8200 of the DG Board for selection between PC and all other inputs 21 ...

Page 22: ...andard RGB signals from the RGB amplifier IC4512 enter IC8200 for selection The selected output passes through the LPF circuit consisting of IC8201 to reduce bandwidth The filtered output is applied to the D Board via pins 26 28 and 30 of the connector DG3 D3 The output of the switch IC8030 is used at the manufacturing plant for testing purposes 22 ...

Page 23: ...for the distribution of dark and bright components The Plasma AI circuit converts the 8 bit signal data to 10 bit signal data The Sub field Processor is used to speed up the scanning process and control the number of sustain periods This increases the brightness and improves the contrast ratio It also creates the two channels of data that drive the C1 and C2 data output boards The D board provides...

Page 24: ... 31 32 and 34 of connector DG3 D3 The sync signals then enter a level shifter IC IC9023 to change the DC Level from 5 to 3 3 volts The output signals of IC9023 enter IC9009 for conversion into digital pulses IC9605 the Sync Processor and Discharge Control circuit produces the Sustain control pulses the Scan control pulses and the data timing pulse for the data drive circuit boards 24 ...

Page 25: ...SC Board Explanation Figure 12 25 ...

Page 26: ...r SC20 provides the drive voltages 140V 100V and 18V as well as the trigger signals to switch the FET transistors The D board switches the FETs on and off to create the distinctive scan signal Each trigger signal switches a drive FET creating a portion of the waveform For example applying the CPH signal to the 140V FET creates the peak portion of the waveform see figure 12 26 ...

Page 27: ...it is applied to the SU and SD boards for de multiplexing The signal is input to a series of shift registers inside the PDP scan driver IC Figure 14 shows an example of the de multiplexing circuit There are six driver ICs on the SU board and six on the SD board 27 ...

Page 28: ...re output to the SS board The erase pulse is output at the beginning of each scan period The pulse is applied to the SS2 and SS3 boards to remove the previous charge for the upper and lower sections of the display panel The sustain pulses are also developed on the D board and are applied after the scan periods 28 ...

Page 29: ...Figure 16 29 ...

Page 30: ... pulses are applied to FET drivers creating the distinctive sustain pulse The drivers switch the voltages 150V 155V and 175V at selected intervals determined by the D board The basic waveform remains constant but the exact number of sustain pulses is determined by the amount of luminance required see figure 17 30 ...

Page 31: ...condary of T402 to create the STB 7V for the system control circuit IC403 regulates the 7V standby voltage to produce the STB5V for the D Board This 7V standby voltage also passes through the diode D410 to enter the power relays RL401 and RL403 When the unit is turned on transistor Q401 turns on to create the ground path for power relay RL401 Transistor Q417 provides the ground path for the In Rus...

Page 32: ...the IC enters pin 4 of IC551 to serve as startup voltage and begin the oscillation of the IC The regulated DC output of IC550 is also applied to the voltage feedback circuit consisting of the optical coupler D565 and Diode D553 The PWM output at pin 3 of IC551 is applied to the transformer s primary As current passes through the transformer magnetic field builds up in its core The primary current ...

Page 33: ...he diodes D557and D560 rectify the AC output voltage at the secondary of the transformer T501 The network consisting of C573 C574 R597 R598 and R600 achieves filtering This output voltage labeled VSUS is applied to the Scan and Sustain boards Voltage regulation is achieved via the feedback circuit comprised of the resistors R602 R606 and the Error Detect IC IC553 The resistor R605 is used to adjus...

Page 34: ...edback circuit consisting of the optical coupler D566 and Diode D554 The PWM output at pin 3 of IC552 is applied to the primary of the transformer T502 As current passes through the transformer magnetic field builds up in its core The primary current passes through the transistor located inside the IC and the two source resistors R569 and R576 The voltage at the transistor s Source increases at a ...

Page 35: ...age enters pin 1 of the IC for transformer sensing Voltage regulation is achieved via the feedback network consisting of D566 D554 and R558 VDA and other Voltage Sources Figure 20c The 12V source The 20V source is primarily used in the A Board It is applied to a regulator IC IC2304 to obtain a 9V output The diode D568 converts the AC voltage supplied by the secondary windings of the transformer T5...

Page 36: ...ce The diode D574 converts the AC output of the secondary windings of the transformer T502 to DR15V This voltage source is applied to the SC and SS boards for Scan and Sustain operations The PA board and fan control circuit also uses the DR15 voltage source The VDA voltage source Pin 11 of the secondary of the transformer supplies the VDA voltage for use on the SS Board This voltage is tied to a r...

Page 37: ... of the MPU IC001 triggering an SOS condition Transistor Q7544 monitors the 3 3V and 2 5V line If any of these supply lines increase in voltage transistor Q7544 goes into conduction causing its collector to go low As a result Q7541 conducts and applies a high to pin 69 of the MPU IC001 triggering an SOS condition The 9 M V and 2 5 M V are also monitored for a drop in voltage A decrease in any of t...

Page 38: ...he main CPU The Scan and Sustain voltages on the SC and SS boards are monitored in a similar manner The 15V Line on the SS board is fed to a voltage divider and the result is compared to a reference voltage The reference voltage is provided by a zener diode If the output of the comparator goes high a transistor turns on effectively grounding the SOS line The SC board uses a similar circuit Additio...

Page 39: ...processing main tuner and the sub tuner Examples of video processing include on screen display tint or contrast as well as many other picture adjustments Bus line 3 reads the data from the Stand by CPU for front panel and remote control operation Additionally bus line 3 reads the condition of the SOS protection lines and transfers this information to the Main CPU In all cases the Main CPU is the m...

Page 40: ...eo and sound functions Information such as channel mapping or customer preferences is stored in the EEPROM IC002 I2 C bus lines 1 and 2 are primarily responsible for video and audio operation Figure 23 shows the connections to the Global core IC s Tuners AV switches and input devices 40 ...

Page 41: ...P5V IC9709 pin 2 Voltage down P Board 5 Power SOS Vsus 170V 15V 20V IC9709 pin 63 Voltage down P Board 6 Fan Stop IC9709 pin 37 Fan 7 SCAN Driver 2 Voltage Energy Recover IC9709 pin 1 Load over Detect at IC6581 SC Board 9 SUS Driver Voltage Energy Recover IC9709 pin 61 Load over Detect at IC6705 SS Board 12 Tuner Power UNR21V UNR14V 2 5V M 9V M 9V S 5V S 3 3V M IC001 pin 69 Voltage down or over cu...

Page 42: ...p 2 The power LED is green at power up It then turns red a few seconds later and blinks on and off 3 The power LED is red at power up and never changes state No Check the P Board Replace the defective component Yes Does the power LED turn on Yes The PF Board is suspected to be defective Do F900 and F901 measure correctly No 42 ...

Page 43: ...oard is probably defective No SS Board is probably defective D Board is probably defective Does the problem exist on all inputs DG Board is probably defective No Yes G Board is probably defective H or DG Board is probably defective Does the problem exist on PC RGB video Does the problem exist on Composite video No Yes Yes Yes Yes No Yes 43 ...

Page 44: ...o be defective YES YES Is the TPSC1 Waveform incorrect The D Board is suspected to be defective Are the voltages at connectors SC2 and SC23 of the SC board correct The Power Supply is suspected to be defective NO NO NO The D Board is suspected to be defective Are the trigger signals at connector SC20 of the SC board correct NO NO YES YES The SC Board is suspected to be defective 44 ...

Page 45: ...e defective YES Is the TPSS1 Waveform incorrect The D Board is suspected to be defective YES Are the voltages at connectors SS11 and SS12 of the SS board correct The Power Supply is suspected to be defective NO NO NO The D Board is suspected to be defective Are the trigger signals at connector SS23 of the SS board correct NO NO YES YES The SS Board is suspected to be defective 45 ...

Page 46: ... a failure where the symptom is localized in a particular area of the screen The figure below can help localize the circuit board that is most likely to be defective In the example in figure 24 one of the two boards C2 and D is likely to be the cause Figure 24 46 ...

Page 47: ...c SD Board 1 Check the status of the LED located on the SC Board if the LED is dark a malfunction of the SC Board is suspected 2 Listen to the buzz noise of the SC board if the buzz noise is not present a malfunction of the SC Board is suspected Suggestions Check the Scan pulse waveform at TPSC1 Use TPSS1 of the SS board to trigger the oscilloscope Verify the input signals at connector SC2 SC23 an...

Page 48: ...xels are faintly lit the defect is most likely located in one of the following boards A SS Board B SS2 Board C SS3 Board 1 Check the status of the LED located on the SS Board if the LED is dark a malfunction of the SS Board is suspected SS Board Figure 29 2 Listen to the buzz noise of the SS board If the buzz noise is not present a malfunction of the SS Board is suspected 3 Verify the input signal...

Page 49: ...t TPSC1 of the SC Board Use TPSS1 of the SS Board to trigger the oscilloscope Proceed to the power sources at connector S check S11 present at connector SS23 and SS12 Verify that the clock and serial data lines from the D board are Figure 30 49 ...

Page 50: ...f the black bar 1 If the pixels are totally dark the defect is most likely located in one of the following boards Figure 31 a SC Board b SU Board upper half of the screen only c SD Board lower half of the screen only 2 If the pixels are dimly lit the defect is most likely located in one of the following boards a SS Board b SS2 Board upper half of the screen only c SS3 Board lower half of the scree...

Page 51: ...Since the C1 board contains the serial to parallel converters for the picture data that drive this portion of the screen the most likely cause for this defect can be localized to the C1 Board or the D Board Symptom No OSD but it has video Suggestion Check signal on the DG board Symptom Burned image pattern is visible Suggestion Access the CAT mode and activate the scroll bar or run the set with a ...

Page 52: ...onfirm the indicated test point below for the specified voltage Adjustment Name Test Point Voltage Potentiometer Vsus P11 pin 2 Vsus 1V R605 Vda P12 pin 1 67 0 0 5V R590 Confirmation Name Test point Voltage 15V P23 pin 1 15 4V 0 5V 15V P7 pin 1 15 2V 0 5V 12V P25 pin 1 11 8V 0 5V Audio 12V P5 pin 7 12 5V 0 8V 5V P25 pin 5 5 1V 0 3V STB 5V P27 pin 4 5 0V 0 3V Fan 15V P10 pin 1 15 4V 0 5V Fan 5V P10...

Page 53: ... Figure 35 for more information about the panel label Name Test point Voltage Volume Vsus TPVSUS SS BOARD Vsus 1V R605 P BOARD Vbk TPVBK SC BOARD 155Vbk 5V R6443 SC BOARD Ve TPVE SS BOARD Ve 1V R6774 SS BOARD Vset TPVSET SC BOARD 218 V 6V Verify Only Vad TPVAD SC BOARD 90 1V R6477 SC BOARD Vda TPVDA SS Board 67V 1V R590 P BOARD VSCN TPVSCN SC BOARD Vad 118V 2V Verify only Refer to the panel label ...

Page 54: ...et the picture mode to Normal and White Balance to Normal Adjustments Adjust the indicated test point for the specified waveform Use TPSS1 as the trigger source Test point Volume Level T1 TPSC1 SC R6523 SC Board 20 15µ Sec T2 TPSC1 SC R6557 SC Board 170 20µ Sec Figure 36 54 ...

Page 55: ...ems in this table Vsus R605 P Board TPVsus SS Vsus 1V P Board Vda R590 P TPVDA SS Board 67V 1V Vbk R6443 SC TPVBK SC 155V 5V Vad R6477 SC TPVAD SC 90V 1V Vset TPVSET SC BOARD 218 V 6V Verify Only SC Board VSCN TPVSCN SC BOARD Vad 118V 2V Verify only SS Board Ve R6774 SS TPVE SS Ve 1V D DG Board White Balance Pedestal and Sub brightness for NTSC Pal HD PC and 625i signals Refer to the Panel label f...

Page 56: ...Test Point locations Figure 38 56 ...

Page 57: ...viceman mode is as follows Using the Remote Control 1 Select SET UP icon and select CABLE mode 2 Select TIMER icon and set SLEEP time for 30 Min 3 Press ACTION twice to exit menus 4 Tune to Channel 124 5 Adjust VOLUME to minimum 0 6 Press VOL down on the receiver Red CHK appears in the upper left corner of the screen 7 Select an active station Note If more than 30 minutes are needed after the rece...

Page 58: ...ID Mode Mode Function Access Button IIC Service Alignment Action CD Complete Diagnostics Software Version Information EEPROM Edit Mute More than 5 seconds SD Status Display MTBF Parameter Action MS Mode Not used ID Not used Important note If the Action and Power buttons of the television are used to exit the Serviceman mode any programmed channels channels caption data and some other user defined ...

Page 59: ... I2 C mode 1 Select the alignment subject by pressing the 1 or 2 buttons on the remote control 2 Select the alignment item by pressing the 4 button on the remote control 3 Adjust the optimum setting by pressing the Volume Up Down buttons on the remote control The data is memorized when you exit the I2 C mode To exit the I2 C mode press the Recall button on the remote control Figure 40 59 ...

Page 60: ...I2 C Menu Structure The values indicated in this flowchart are sampled data Figure 41 60 ...

Page 61: ...ange MiCom Software version Memory data version D Memory data version H Memory data change Address Data 0 11 0 11 1 21 05 0 0 0 0 OK 8 63 78 3F Factory New data Original data Data Memory data change Address Memory data version H Memory data version D MiCom Software Version Address Change by pressing the Up Down buttons on the remote control 0 0 Change by pressing the Left Right buttons on the remo...

Page 62: ...on button on the remote control OSD Input command Check Power Protect MTBF Parameter WT PT 23 25 27 27 27 27 28 25 25 37 72 12 Remote Control mode A B History of remote control command Factory use Cumulative time for power on condition Unit hour Number of Power On Cycles To exit the SD mode press the Action button on the remote control 62 ...

Page 63: ...ack 2 area and no emission occurs in the black 0 area Step 4 Under the Chroma Control setting Set Gun off to 3 Only blue pixels emitting Step 5 Access the RGB Sub Adjust B Sub Bright setting and adjust B Sub bright so that blue pixel emission starts at black 2 area and no emission occurs in the black 0 area Step 6 Under the Chroma Control setting Set Gun off to 6 Only red pixels emitting Step 7 Ac...

Page 64: ... the 20 IRE pattern and 80 IRE patterns and verify that the drive and cutoff settings match the settings in Table 1 adjust as necessary Step 10 Adjust the All Drive Settings value to FC Step 11 Reapply the 20 IRE pattern and verify the light settings match the table below adjust as necessary Table 1 Color Temperature X Y Cool High 0 276 0 276 Normal Mid 0 288 0 296 Warm Low 0 313 0 329 Step 12 Pre...

Page 65: ...apply the 20 IRE pattern and 80 IRE patterns and verify that the drive and cutoff settings match the settings in Table 1 adjust as necessary Step 10 Adjust the All Drive Settings value to FC Step 11 Reapply the 20 IRE pattern and verify the light settings match the table below adjust as necessary Table 1 Color Temperature X Y Cool High 0 276 0 276 Normal Mid 0 288 0 296 Warm Low 0 313 0 329 Step 1...

Page 66: ...ion starts in the 2 area and there is no emission in the 0 area Step 3 Write down all cut off data Step 4 Set the white balance settings to Normal Step 5 Adjust all the cut off values to the same data values of the Cool mode settings Step 6 Set the white balance settings to Warm Step 7 Adjust all the cut off values to the same data values of the Cool mode settings Step 8 Change the pattern to HD a...

Page 67: ...3 3 Press and hold the MUTE button on the remote control for a few seconds The display will change from the standard serviceman mode setting to the EEPROM address data display EEPROM Address Data Display 4 Press the Channel Down button of the remote or receiver to select the EEPROM ADDRESS 1584 5 Press the Volume Up button of the remote or receiver to set the data at EEPROM address to 01 Data 01 a...

Page 68: ...he last volume level in memory when Initial Volume is Off Note When the Initial Vol is larger than the Maximum Vol make the Initial Vol and Maximum Vol the same value MAXIMUM VOL LEVEL Limits the maximum Volume level Range 0 to 63 The receiver allows the user to adjust the volume level up to the Maximum Vol selected Note When the Initial Vol is larger than the Maximum Vol make the Initial Vol and ...

Page 69: ...mote is inhibited 8 Push the Power button of the receiver or the remote control to hide the Serviceman mode menu 9 Press the Power button on the front panel to store the changes the Hotel mode is now active Note To return the unit to normal operation use steps 1 through 5 to change the data at EEPROM address 1584 to 00 the Hotel mode is now disabled All normal user functions are restored 69 ...

Page 70: ...her Products 1 800 572 2672 Authorized Service Centers only access code required Fax 1 800 348 7315 1 201 392 4207 Non authorized limited time access Other Numbers 1 800 833 9626 Parts Dept 1 800 458 5397 Musical Instruments 1 201 392 4843 Telephone PBX Systems 1 800 414 4408 Cellular Phones 1 877 924 2473 Massage Loungers 1 201 392 4281 Commercial MWO Hotel Televisions 70 ...

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