Y6 COLOR TV CHASSIS INTRODUCTIONThe Y6 Series Chassis is a Leader TV Set produced by Philips Consumer Electronics Companyfor the 1997 model year. The Y6 is used in TV sets with 13 and 19 inch CRTs. The chassisorientation in relation to the cabinet is front to rear in the Y6 design (sometimes called "North-South"), because the chassis is longer in this direction than across. The Y6 tuning systemfeatures 181 channels with on-screen display. The main tuning system uses a tuner along withtwo ICs mounted on the Main Chassis, which include a microcomputer IC and a memory IC. Themicrocomputer communicates with the memory IC, the customer keyboard, the remote receiver,the U/V tuner, the TV signal processor, and the audio output IC. The memory IC retains thesettings for favorite stations, customer control settings, and Service/Factory Setup Data.The chassis features a Very Large Scale Integration (VLSI) IC for TV signal processing. This ICperforms video IF, sound IF, AGC control, horizontal signal processing, vertical signal processing,horizontal/vertical synchronization, and chrominance/luminance processing. On-screen graphicsgeneration and closed caption decoding are done within the microcomputer and the signals aresent to the TV signal processor. The on-screen graphics information is placed on the main signalwithin the TV signal processor.The Y6 chassis features a Switching Mode Power Supply for the main voltage source. A "HOT"ground reference is used in the primary side of the power supply. A "COLD" (signal) ground fromthe secondary of the power supply is used throughout the rest of the chassis. AN ISOLATIONTRANSFORMER IS REQUIRED WHEN DOING SERVICE ON ANY VERSION OF THE NEWCHASSIS.
SIGNAL FLOWThe incoming TV RF signal is applied to the U/V tuner via the antenna and RF input. The45.75mhz IF signal is developed and amplified within the U/V Tuner. The amplified IF signal issent from Pins 10 and 11 of the U/V Tuner to the SAW Filter, 1015. The SAW Filter, producesbandpass shaping for the IF signal before it is applied to the TV Signal Processor 7225 forprocessing. AGC (for the Tuner) and AFT (for the Microcomputer) are developed within 7225and then routed to the Tuning System for RF Amp gain control and Oscillator frequencycorrection. The AGC level is preset at Pin 49 of 7225 by 3264. Further AGC correction is madeat Pin 48 of 7225 by 7250, 7251, 7252, and 7253 by sampling the Sandcastle waveform.Sound IF signal processing for the Y6 Chassis is performed by coupling the 4.5MHz Sound IFsignal from 7225, pin 7, via a Buffer Amplifier, 7214, and 4.5mhz Band Pass Filter, 1102, and into7225, Pin 5. Audio is output from Pin 50 and applied to the Smart Sound circuit 7124 and 7116via 7183. Bass and Treble are controlled by the Microcomputer, 7601, Pins 9 and 10. Audiofrom the Smart Sound Circuit is applied to 7121 Pin 2 for the 13" Set or 7120 Pin 3 for the 19"Set. External Audio from another source is applied to 7225 Pin 6.Composite video from 7225, Pin 48, is buffered by 7214 and then passed through a 4.5mhz Trap,1206, to remove any sound products present. The Closed Caption video comes from 7214 and isapplied to the Microcomputer, 7601, Pin 23, via 7607. Composite internal video is applied to7225, Pin 13, while External video is applied to 7225, Pin 15. This video is applied to an internalLuminance Chrominance Switch which applies the Luminance signal to an internal Matrix and theChroma signal to a Demodulator. The Demodulated R-Y and B-Y are outputted from 7225, Pins30 and 31, and reapplied to 7225, Pins 28 and 29.Brightness, Picture, Sharpness, Color, and Tint, control voltages are applied to 7225 fromMicrocomputer 7601 via individual Control Lines. Red On Screen Display, Blue OSD, GreenOSD, and Fast Blanking are applied to 7225 from Microcomputer 7601 via individual lines. TheRed, Green, and Blue signals from 7225 are applied to the CRT Board. On the CRT Board,these signals are amplified before being applied to the CRT. Drive and Cutoff controls for CRTSet-Up are located on the CRT board.Horizontal and Vertical signals are also developed within 7225. There is no adjustment for theHorizontal Oscillator. The horizontal circuit uses a count down system that gets its basefrequency from the 3.58 Mhz circuit. A DC reference voltage from 3420, Horizontal CenteringControl, is applied to 7225 Pin 39 for adjustment of the Horizontal centering of the video on theraster.When the set is turned On, a High is Output from 7601 Pin 19 to provide pull up voltage for 7225Pin 37. The Horizontal Drive from 7225 Pin 37 is sent to 7440 and 7441, Horizontal Driver andPulse Shaping circuit. Horizontal drive is then applied to the Base of 7445 to drive 5445, theIntegrated Flyback Transformer. A horizontal pulse is also made available for the chassis fromthe output circuit of the Horizontal Output transistor. The IFT develops the High Voltage, ScreenVoltage, Focus Voltage, and Filament Voltage for the Picture Tube. Scan derived voltagesprovided by the IFT for use by the chassis are the 160V, 26V, 5.5V, and 9V Sources. If theVoltage output from 5445 goes high, a sample is sent to 6651, 9.1V zener, turning On 7650, andcausing 7601 Pin 16 to go Low. The Microcomputer 7601 turns the set Off. A High at 7601, Pin19, also turns on 7668 which is connected to the 9V Scan Derived Supply via 6651. If the 9VScan Derived Supply fails, 7601 Pin 16 goes Low turning the Set Off. The High at 7601 Pin 19 inaddition, turns 7608 Off, turning 7609 On, switching the Scan Derived 5.5V Source to 7601 Pin
38.The Vertical signal is output from 7225 Pin 43 and is applied to the Vertical Output IntegratedCircuit 7401. The vertical signal is output from 7225 and applied to the Vertical Yoke. Feedbackfrom the vertical circuit is fed to 7225, Pin 41. Vertical Sync is output to 7681 and theMicrocomputer 7601 Pin 37 to synchronize on screen display and closed caption.POWER SUPPLYY6 CHASSIS POWER SUPPLYWhen a 120Vac Source is connected to the Y6 Chassis, approximately 160Vdc is developed bythe Bridge Rectifier circuit. The 160 volts dc goes through 5545 to the FET switch. The startvoltage for the Switching Mode Power Supply is taken from the hot leg of the input ac.The Power Supply consists of a single integrated circuit operating as a Free-Running SwitchingMode Power Supply. The frequency of operation varies with the circuit load. There is noseparate power supply for standby; instead, the Power Supply turns On when AC is applied. TheSwitching Regulator IC starts switching when the initial voltage is applied through the Startupcircuit. The Switching Regulator turns the Switch On and Off to allow current flow through theprimary of transformer 5545. Energy stored in the primary during the On-time is delivered to thesecondaries during the Off-time. Feedback from the HOT secondary is used to control theSwitching Regulator. Positive Voltage from the HOT secondary is used as B+ for the SwitchingRegulator.The voltages needed to operate the television are developed from the secondaries of 5545.The Y6 Power Supply is a pulse width modulated, fixed frequency, switching mode power supply.The Power Supply features a Slow Start and has Overvoltage, Under voltage, Overload, andUnder-load protection. Feed back is accomplished by sensing the voltage of the Hot groundsecondary winding. In the Standby Mode, the operating frequency of the supply is approximately20KHz. It switches to 70KHz in the Full Power mode. The Power Supply maintains constantoutput voltages in both the Standby and Full Power modes. The output secondaries are 10 to 14volts for the Audio Circuit, 95 volts for the Horizontal Drive, and 10 volts for the HorizontalOscillator. The 10 volts supply is fed to a 5 volt regulator, 7500 to produce 5 volts for themicroprocessor.
Chassis Identification And Interchangeability NoticeChassis IdentificationAn identification label is located on the outside of the cabinet back. The first two characters (19)indicate the screen size of the television and the next two characters (Y6) identify the basicchassis series. The next four numbers (7562) following the 04, indicate the Service Manualnumber for the chassis. Minor changes may not be identified within the letters, however, they willbe called out on the schematic as Early Production (E.P.) and Late Production (L.P.) changes.When ordering parts or requesting technical assistance or information, the complete chassisnumber must be supplied (e.g. 19Y604-7562).Interchangeability NoticeImportant: While the following holds true in most cases, always refer to the most up-to- date information for confirmation of interchangeability.The 8 digit Base Number identifies a family of assemblies. The remaining 4 characters (called theGroup No.) indicate the type of INTERCHANGEABILITY within the family.Example: 00EMY627 A001 Base No. Group No.Note: Families having different Base Numbers cannot be interchanged.The ninth digit (first digit of the group number) identifies the groupINTERCHANGEABILITY level. This will be an alpha character. Higher groups may replacelower groups, but lower groups cannot be substituted for higher groups.Example: 00EMY627 A001 00EMY627 B002 00EMY627 C00300EMY627 B002 CAN BE REPLACED BY A C003 BUT NOT BY AN A001. IN ADDITION, AC003 CAN BE USED IN PLACE OF EITHER A B002 OR AN A001.The last two digits of the identification number indicate running changes. When aparticular identification number is initially assigned, it will be a001. Any change whichdoes not significantly change the operational characters or the external wiringconfiguration, is a running change within the group. It allows bi-directionalINTERCHANGEABILITY within the group.Example: A001 can be used in place of A003, and A003 can be used in place of A001.However, if a significant change does occur (which will only allow higher revision substitution), thegroup identifier (9th position character) must change.Example: 00EMY627 00EMY627 A002 00EMY627 A003 00EMY627 B004 00EMY627 B005 A001 (Early (Late Production) Production)
Note: 00EMY627 A001 is the initial identification number. All assemblies in the "A" group (9th position character) are interchangeable with each other. All of the assemblies in the "B" group are interchangeable with each other, and any "B" group assembly can be substituted for an "A" group. However, an "A" group assembly cannot be substituted far a "B" group assembly.Main Chassis Schematic Notes: UNLESS OTHERWISE SPECIFIED: 1. ALL WAVEFORMS WERE TAKEN UNDER THE FOLLOWING CONDITIONS: LINE VOLTAGE MAINTAINED AT 120VAC, 60HZ VIA AN ISOLATION TRANSFORMER CUSTOMER CONTROLS SET TO MID-RANGE. 2. VOLTAGES SHOWN WITHOUT BRACKETS AND ALL WAVEFORMS WERE TAKEN WITH AN NTSC SIGNAL GENERATOR DELEVERING 10mVp-p AT ANTENNA TERMINALS. 3. VOLTAGES SHOWN WITHIN BRACKETS WERE TAKEN WITH NO SIGNAL APPLIED; THEY ARE LISTED ONLY WHERE AN APPRECIABLE CHANGE WAS NOTED. 4. VOLTAGES SHOWN ENCLOSED WITHIN RECTANGLES WERE TAKEN WITH THE SET IN STAND-BY MODE (POWER SUPPLIED TO THE CHASSIS), SET TURNED OFF. 5. ALL VOLTAGES ARE POSITIVE DC WITH RESPECT TO GROUND AND VARY DUE TO NORMAL PRODUCTION TOLERANCES. 6. *= INDICATES A COMPONENT THAT WILL VARY DEPENDING ON SCREEN SIZE, PRODUCTION DATES AND OPTIONAL FEATURES INSTALLED. PLEASE SEE THE REPLACEMENT PARTS LIST FORSPECIFIC PART INFORMATION. = INDICATES THESE COMPONENTS ARE SMD "CHIP TYPE" COMPONENTS AND AS SUCH WILL BE LOCATED ON THE BOTTOM SIDE OF THE PCB. 7. SPARK GAPS SHOWN ON THE CRT SCHEMATIC ARE INTERNAL TO THE CRT SOCKET. INDICATES THE NEED FOR A HIGH VOLTAGE SCOPE PROBE (100: 1). THESE WAVEFORMS (#27) AT PINS 3 THROUGH 7 OF IC7600 IS PULSE WIDTH MODULATED.THE FREQUENCY WILL VARY DEPENDING UPON CUSTOMER CONTROL SETTINGS THESE VOLTAGES WILL VARY SUBSTANTIALLY DEPENDING UPON G2 AND CUTOFF CONTROL SETTINGS (WHICH WILL VARY DEPENDING UPON THE CHARACTERISTICS OF A PARTICULAR PICTURE TUBE). VOLTAGES WILL ALSO VARY DEPENDING UPON CUSTOMER CONTROL SETTINGS. (SEE NOTE ONE)
11. THE NUMBERS 1 THROUGH 41, WITHIN RECTANGLES, CORRESPOND TO WAVEFORM PHOTOGRAPHS. 12. FOR VOLTAGE, WATTAGE AND TOLERANCE RATINGS OF RESISTORS AND CAPACITORS PLEASE SEE THE ELECTRICAL REPLACEMENT PARTS LIST. INDICATES PCEC REPLACEMENT PART NUMBER ONLY.Waveforms Notes: THE NUMBERED WAVEFORM PHOTOS TO THE RIGHT REFER TO THE LOCATION OF THE NUMBERS WITHIN RECTANGLES INDICATED ON THE SCHEMATIC. 1. ALL WAVEFORM PHOTOGRAPHS WERE TAKEN UNDER THE CONDITIONS AS STATED IN STEP 1 OF THE MAIN CHASSIS SCHEMATIC NOTES. 2. SWEEP TIME/CM SETTINGS ARE SHOWN BELOW PHOTOS IN THE CALIBRATED POSITION. HORIZONTAL POSITIONING OF THE WAVEFORMS WAS ADJUSTED FOR MAXIMUM CLARITY. a. INDICATES THE NEED FOR A HIGH VOLTAGE SCOPE PROBE. b. 5445 Pin 1 7.5 Vp-p 5445 Pin 7 80 Vp-p 5445 Pin 9 24 Vp-p c. 5445 Pin 4 54 Vp-p 5445 Pin 5 84 Vp-p 5445 Pin 6 225 Vp-p d. 5545 Pin 10 34 Vp-p 5545 Pin 11 23 Vp-p 5545 Pin 13 23 Vp-p 5545 Pin 14 200 Vp-p e. 5545 Pin 1 40 Vp-p 5545 Pin 4 375 Vp-p f. IC7401 Pin 1 1.4 Vp-p IC7401 Pin 3 1.3 Vp-p g. IC7601 Pin 2 3.3 Vp-p IC7601 Pin 3 4.1 Vp-p IC7601 Pin 4 3.3 Vp-p IC7601 Pin 5 4.1 Vp-p IC7601 Pin 6 4.1 Vp-p IC7601 Pin 7 4.2 Vp-p
S = Safety component - Replace with Philips part only.FEATURE CHARTPR1302 C1FEATURES: Factory Presets Wake Up Automatic Cable DetectPR1303 C1FEATURES: Factory Presets Wake Up Automatic Cable DetectXR1302 C1FEATURES: Factory Presets Wake Up Automatic Cable DetectHD1918 C1FEATURES: Factory Presets Wake Up Volume Limiter Automatic Cable DetectPR1902 C1FEATURES: Factory Presets Wake Up Automatic Cable DetectXR1902 C1FEATURES: Factory Presets Wake Up Automatic Cable Detect
14LL17 01FEATURES: Factory Presets AV Source Auto Fine Tuning14LL17 11FEATURES: Factory Presets AV Source Auto Fine Tuning14LX17 03FEATURES: Factory Presets AV Source Auto Fine Tuning20LL27 01FEATURES: Factory Presets AV Source Auto Fine Tuning20LL27 11FEATURES: Factory Presets AV Source Auto Fine Tuning20LX27 03FEATURES: Factory Presets AV Source Auto Fine Tuning
13Y6(7560)27 IC7601 pin 7 28 29 304.2 V p-p 5 V p-p 0.6 V p-p 5 V p-p20 usec 5 msec 20 usec 5 msec31 32 33 344.5 V p-p 4.8 V p-p 0.7 V p-p 4.8 V p-p20 usec 20 usec 20 usec 5 msec35 36 371.6 V p-p 1.25 V p-p 4.6 V p-p5 msec 0.2 usec 20 usec
Service Adjustment Notes:Unless Otherwise Specified:1. All service adjustments are "hot" voltagewise. For maximum safety, ensure the use of properly insulated tools.2. Refer to the Y6 Chassis Component Location Diagram for quick location of test points and adjustable components.3. Grid Locations (Ex.: D-2) next to the reference numbers for the controls refer to the Main Chassis Printed Circuit Board.
Focus Adjustment1. Tune the set to a local or cable station.2. Adjust the Focus Control (located on the Flyback Transformer) for best picture details at high light conditions.95 Volt Adjustment1. Place a DC voltmeter on the cathode of 6550.2. Adjust 3540 (95 Volt Adjust) for 95 volts on the DC voltmeter.RF AGC Adjustment1. Tune to a normally snow free station.2. Adjust potentiometer 3264 (RF AGC Adjust, F-2) to its fully counterclockwise position.3. Slowly turn potentiometer 3264 clockwise to a point slightly beyond the point of minimum snow.NOTE: do not turn the control any further as it may result in an overloaded picture on the face of the CRT. (Caused by a strong station).IF AFT Alignment1. Ensure the set is in Antenna mode (not cable) and tune the receiver to a good local air signal.2. Temporarily ground jumper 9689.3. Place a DC voltmeter at pin 11 of the microcomputer (IC7601)4. Adjust coil (5260) for 2.5 volts DC on the voltmeter.Vertical Height Adjustment1. Apply a crosshatch pattern to the antenna/cable input terminal.2. Observe the crosshatch pattern on the screen and adjust potentiometer 3410 (F-4) (Vertical Height Adjust) for slight overscan. (3/8" for 13" models and 1/2" for 19" and 20" Models.)Horizontal Centering Adjustment1. Apply a color bar pattern to the antenna/cable input terminal.2. Observe the color bar pattern on the screen and adjust potentiometer 3420 (H-2) (Horizontal Center Adjust) so that the left most color bar and the right most color bar are the same width.
Master Screen (VG2) Control Setup1. Apply an NTSC color bar signal to the antenna/cable input terminal and tune to the active channel.2. Enter the customer control menu by pressing the Menu button on the remote control transmitter.3. Set the Brightness, Picture, and Tint controls to midrange, then exit the customer control menu.4. Using an oscilloscope, measure and note the peak to peak voltage of each CRT cathode. Connect the oscilloscope in turn to the leads of resistors 3315, 3335, and 3355, (All of these controls are on the CRT Board) which connect to the cathodes.5. After measuring all three voltages, reconnect the oscilloscope to the resistor at which the highest voltage reading was obtained.6. Adjust the Master Screen (VG2) Control (located on the flyback transformer) to obtain a peak to peak voltage reading of approximately 55Vp-p. Note that there will also be a dc voltage component of the signal.Degaussing the Television1. Position the television so that the screen faces the direction it will be facing when in use.2. Ensure the set is turned off.3. Move a degaussing coil in a circular motion slowly around the sides and the front of the set.4. Withdraw the degaussing coil at least six feet from the television before disconnecting it from its power source.Convergence and Purity Adjustment procedureTHE FOLLOWING ADJUSTMENTS SHOULD BE PERFORMED IN THE FOLLOWING ORDER:PRE-CONVERGENCE PROCEDURECOLOR PURITY ADJUSTMENTSTATIC CENTER CONVERGENCE ADJUSTMENTDYNAMIC EDGE CONVERGENCE ADJUSTMENTPre-Convergence ProcedureNote: The degaussing procedure should be performed prior to this adjustment.1. Place the multi-pole Purity and Convergence Assembly with the 2-Y pole purity rings directly in the gap between the G2 and G3 (focus) grids as shown in figure 2.2. Apply a center cross or crosshatch pattern to the antenna/cable input terminal.3. Set potentiometer 3330 (Green Cutoff Control - on CRT Board) to its fully counterclockwise position.4. Loosen the yoke clamp screw, pull the yoke back, and remove the three yoke wedges.5. Slide the yoke all the way forward so that it rests against the bell of the CRT.6. Tighten the yoke clamp screw so that the yoke does not drop away from the bell of the CRT.7. Slowly spread, and if necessary, rotate the 2-Y pole purity rings so that the red and blue lines are at least parallel and preferably coincide at the 6:00 and 12:00 positions. (Refer to figure 3.)
Figure 2 - Convergence and Purity AssemblyFigure 3 - 2X/2Y Rotate/SpreadColor Purity Adjustment1. Connect a solid white pattern signal to the antenna/cable input terminal.2. Set potentiometer 3340 (CRT Board) (Blue Drive Control) to its fully clockwise position.3. Set potentiometers 3330 (CRT Board) (Green Cutoff Control) and 3350 (Blue Cutoff Control) fully counterclockwise.4. Set potentiometer 3300 (CRT Board) (Red Drive Control) fully counterclockwise and potentiometer 3310 (Red Cutoff Control) fully clockwise.5. Slowly spread the 2-X pole purity rings to center the red portion of the screen, leaving the same amount of green on one side of the screen there is blue on the other side.6. Tighten the yoke clamp screw slightly so that the yoke may be moved with some friction.7. Proceed to the Static Center Convergence Adjustment.Static Center Convergence Adjustment1. Apply a center cross or crosshatch pattern to the antenna/cable input terminal and observe the screen to ensure that the yoke is not tilted. If necessary, rotate the yoke to obtain a level raster.2. Set potentiometer 3330 (Green Cutoff Control-on CRT Board) fully counterclockwise.3. Set potentiometers 3300 (Red Drive Control-on CRT Board) and 3340 (Blue Drive Control-On CRT Board) to counter-clockwise.4. Set potentiometers 3310 (Red Cutoff Control) and 3350 (Blue Cutoff Control-On CRT Board) fully clockwise.5. Slowly spread, and if necessary, rotate the 4-pole magnetic rings to converge red and blue lines at the center of the screen.
6. Set potentiometer 3330 (Green Cutoff Control-On CRT Board) to its fully clockwise position.7. Slowly spread, and if necessary, rotate the 6-pole magnetic rings to converge red/blue on green lines at the center of the screen.8. Repeat steps five through seven for optimum performance.9. Proceed to the Dynamic Edge Convergence Adjustment.Dynamic Edge Convergence AdjustmentNote: To secure the correct position of the deflection yoke, three rubber wedges are used. They are ultimately to be placed as shown in figure 4c or figure 5c .1. Apply a crosshatch pattern to the antenna/cable input terminal.2. Set potentiometer 3330 (Green Cutoff Control-On CRT Board) fully counterclockwise.3. Tilt the yoke up and down to converge the red and blue vertical lines at the 6:00 and 12:00 positions and the red and blue horizontal lines at the 3:00 and 9:00 positions (refer to figure 6) . When the correct position has been found, place a rubber wedge between the yoke and the CRT. If the yoke is tilted up, place wedge one as shown in figure 4a ; if it is tilted down, place wedge one as shown in figure 5a.4. Tilt the yoke to the left and right to find the point of best possible convergence of the red and blue lines at the edges, top and bottom of the screen as shown in figure 7 . When the correct position is located, place wedges two and three as shown in figure 4b or figure 5b.5. Remove wedge one and place it in the final position as shown in figure 4c or 5c.6. Set potentiometer 3330 (Green Cutoff Control-On CRT Board) fully clockwise.7. Proceed to the White Balance Adjustment.Figures 4 and 5Figures 6 and 7
White Balance Adjustment1. Enter the customer menu and set the Picture, Color and Brightness controls to zero.2. Apply a white raster signal to the antenna input.3. Turn the Master Screen Control (VG2) fully counter-clockwise.4. Place a Voltmeter at Pin 3 of the CRT Cathode.5. Adjust 3350 (Blue Cutoff Control - on CRT Board) for a reading 110 volts DC on the voltmeter.6. Place a Voltmeter at Pin 5 of the CRT Cathode.7. Adjust 3310 (Red Cutoff Control - on CRT Board) for a reading 110 volts DC on the voltmeter.8. Place a Voltmeter at Pin 7 of the CRT Cathode.9. Adjust 3330 (Green Cutoff Control - on CRT Board) for a reading 110 volts DC on the voltmeter.10. Apply a crosshatch pattern to the antenna input.11. Turn the Master Screen Control (VG2) clockwise until the dark areas of the cross hatch begin to illuminate.12. Now turn the Master Screen Control (VG2) counter-clockwise until the dark areas are just extinguished.13. Apply a color bar pattern to the antenna input (No chroma will be visible).14. Adjust (in small increments) the cutoff controls (3310 Red Cutoff Control) (3330 Green Cutoff Control) (3350 Blue Cutoff Control) to make the darkest color bar gray.15. Adjust the drive controls (3300 Red Drive Control) (3340 Blue Drive Control) to make the brightest color bar white.NOTE: the controls will interact. Reduction of the Red Drive may require reduction of the Red cutoff, etc..CHASSIS SERVICE MODEThe Y6 chassis service mode provides information about features, software version, and errorcodes. Use the following seven-button sequence on the remote control to enter the service mode:0-6-2-5-9-6-MenuNote that this sequence must be entered consecutively without allowing the on-screen display to time out between entries.To exit the service mode, turn the television off with the remote control transmitter Power button.When the unit is operating in service mode, all normal on-screen displays are suppressed andreplaced by a special service display. A sample display is shown below.
Explanation of DisplayThe first number (74000 in the example shown above) is a numerical representation of thefeatures of the set.The second number (00E8 in the example) is a run timer. This display will increment based onthe amount of time the set has been on.The third number (1.16.4 in the example) shows the software ID (1), the software version (16),and the cluster number (4).The S indicates that the service mode is active.The five most recent errors are encoded on the following line of the display (in the exampleabove, no errors have been recorded, because all five registers display zeroes). The most recenterror will be displayed in the register nearest the word "ERROR." The error codes and theirmeanings are shown below:Code Meaning1 Micro RAM Error3 EEPROM Checksum Error6 EEPROM Error7 Tuner Error (PLL)The bottom line is a two-letter representation of the features of the set (VI in the example). Thenumber following the feature code will be either one or zero, depending on whether or not thefeature is active (1 means the feature is active, 0 means it is not). The two-letter codes and theirmeanings are shown below:Code MeaningVI Factory Presets (the set will go into "setup" mode when turned on)AC Auto Cable (sets cable/antenna during auto program)AS Auto Scan (automatic scanning and programming of active channels)VL Volume LimiterAV Aux InputWU Wake UpNote that if the memory IC (EEPROM) is replaced during service, the microprocessor will writedefault values into the EEPROM when the set is initially powered on. No other action is requiredof the servicer except to set features.To exit the service mode and erase the error codes, turn the unit off with the power button on theremote control, then unplug the ac cord. Breaking the ac ensures that the microprocessor will
download new settings from the EEPROM IC when power is reapplied to the set. To save theerror codes, unplug the ac cord without turning off the set. When the power is turned back on, theservice mode will still be active.