AOC 791V-1C Schematic

SERVICE MANUAL

COLOR MONITOR

(7Alr Series)

41AA791V-AOC-A00

P/N : A791V-1C-01-A Date: Dec-18-01 Ver : A00

THESE DOCUMENTS ARE FOR REPAIR SERVICE INFORMATION ONLY. EVERY REASONABLE EFFORT HAS BEEN MADE TO ENSURE THE ACCURACY OF THIS MANUAL; WE CANNOT GUARANTEE THE ACCURACY OF THIS INFORMATION AFTER THE DATE OF PUBLICATION AND DISCLAIMS LIABILITY FOR CHANGES, ERRORS OR OMISSIONS,

MANUFACTURE DATE : December . 2001

TABLE OF CONTENTS

PAGE

1. SPECIFICATIONS ..................................................................................................... 3-4

2. PRECAUTION AND NOTICES ................................................................................ 5

2-1 SAFETY PRECAUTIONS .............................................................................. 5

2-2 PRODUCT SAFETY NOTICE ....................................................................... 5

2-3 SERVICE NOTES ........................................................................................... 5

2-4 HIGH VOLTAGE WARNING ....................................................................... 6

3. OPERATING INSTRUCTIONS ................................................................................ 7

4. ADJUSTMENT .......................................................................................................... 8

4-1 ADJUSTMENT CONDITIONS AND PRECAUTIONS ............................... 8

4-2 MAIN ADJUSTMENTS ................................................................................. 8

4-3 ADJUSTMENT METHOD ............................................................................. 8-11

5. CIRCUIT DESCRIPTION .......................................................................................... 11-14

6. TROUBLE SHOOTING CHART .............................................................................. 15

6-1 NO RASTER, CRT RELATIVE CIRCUIT PROBLEMS .............................. 15

6-2 ABNORMAL DISPLAY ................................................................................. 17

6-3 NO BLANKING ........................................................................................... 18

6-4 HOR. /OSC /DEF /HV CIRCUIT FAULT ...................................................... 18

6-5 ABNORMAL HORIZONTAL DEFLECTION .............................................. 19

6-6 ABNORMAL VERTICAL SCANNING ........................................................ 20

6-7 SIDE-PIN CUSHION DISTORTION ............................................................. 20

6-8 POOR FOCUS ................................................................................................. 21

6-9 NO SOUND (FOR AUDIO MODEL ONLY)..................................…........... 21

6-10 POWER SUPPLY TROUBLE SHOOTING CHART .................................... 22

7. MECHANICAL OF CABINET FRONT DIS-ASSEMBLY...................................... 23

8. PARTS LISTING ....................................................................................................... 24

9. BLOCK DIAGRAM (DEFLECTION) ....................................................................... 42

10. IC BLOCK DIAGRAMS............................................................................................ 43

11. PCB LAYOUT ............................................................................................................ 47

12. SCHEMATIC DIAGRAM ......................................................................................... 49

1. SPECIFICATIONS FOR 7Klr SERIES COLOR MONITOR

1. CRT : 43.2CM(17") 90 Deflection, 29mm Neck, Pure flat 0.25mm Dot Pitch, Non-Glare Screen

2. Viewable image Size: 40.6CM (16") diagonal

3. Display Color: Unlimited Colors

4. External Controls: Power On/Off, OSD key, Function knob: Contrast, Brightness, H-Size, H-Center, V-Size, V-Center, ZOOM, Pincushion, Trapezoid, Pin-Balance, Parallelogram, Rotation, Moire Reduce,H-Convergence, V- Convergence language select, Recall, Degaussing, Color Temperature.

5. Input Video Signal

Mode 1 Mode 2 Mode 3 Mode 4

Horiz. Sync: TTL Level TTL Level TTL Level TTL Level

Negative Negative Negative Positive

Vert. Sync: TTL Level TTL Level TTL Level TTL Level

Positive Negative Negative Positive

Horizontal: 640 (H) 720 (H) 640 (H) 800 (H) Vertical : 480 (V) 400 (V) 480(V) 600 (V) Fh (kHz): 31.47 31.47 43.3 53.67 Fv (Hz) : 60 70 85 85

Mode5 Mode 6 Mode7 Mode 8 RGB Analog RGB Analog RGB Analo g RGB Analog

Horiz. Sync: TTL Level TTL Level TTL Level TTL Level

Positive Positive Positive Positive

Vert. Sync: TTL Level TTL Level TTL Level TTL Level

Positive Positive Positive Positive

Horizontal: 1024 (H) 1280 (H) 1280 (H) 1600 (H) Vertical : 768 (V) 960 (V) 1024 (V) 1200 (V) Fh (kHz): 68.6 85.9 91.1 93.8 Fv (Hz) : 85 85 85 75

6. Display Size Horizontal: 310 mm Vertical: 232.5 mm

7. Scanning Frequencies Horizontal: Vertical:

8. Factory Preset Timings: 8 User Timings: 20

9. Misconvergence Center: 0.3 mm Max. Corner: 0.4 mm Max.

10. Video Bandwidth: 200 MHz

GB Analog RGB Analog RGB Analo g RGB Analog

30KHz ~ 96KHz 50 Hz ~ 160 Hz

11. Power Source: Switching Mode Power Supply AC 100 ~240V, 50/60Hz Universal Type

12. Operating Temperature: 10

C to 35OC Ambient

13. Humidity : 10% to 85% Relative, Non-Condensing

• Weight: 17.0 Kgs(Net), 20.5Kgs(Gross)

15 Dimensions Monitor:

Carton: Monitor:

570(W) × 530(H) × 540(D) mm 430(W) × 416(H) × 440(D) mm

16. External Connection :

15 Pin D-type Connector AC Power Cord

17. Regulations: UL, CSA, FDA, FCC, TÜV/GS, CE(For Europe Area or other required Area), MPR-II,TCO’99

2. PRECAUTIONS AND NOTICES

2-1 SAFETY PRECAUTIONS

1. Observe all caution and safety related notes located inside the display cabinet.

2. Operation of the display with the cover removed, may cause a serious shock hazard from the display power supply. Work on the display should not be attempted by anyone who is not thoroughly familiar with precautions necessary when working on high voltage equipment.

3. Do not install, remove or handle th e picture tube in any manner un less shatter-proo f goggles are worn. People who

are not so equipped should be kept away while handling picture tube. Keep picture tube away from the body while handling.

4. The picture tube is constructed to limit X-RAY radiation to 0.5 mR/HR. For continued protection, use the

designated replacement tube only, and adjust the voltages so that the designated maximum rating at the anode will not be exceeded.

5. Symbol “

characteristics as specified in the parts list may create shock, fire or explode etc.

6. Symbol “ ” means X-ray relative parts. Before replacing any of these components please read the parts list in this

manual carefully to avoid creating higher anode voltage or x-ray. Especially for sealed controls, such as VR901, VR902, VR401 and FBT screen VR etc, which were sealed by the manufacturer once their optimum position has been set, please don’t dismantle them as your likes, otherwise you will break or damage the component. If you need replace the parts with sealed control, please adjust the relative VR to make sure the B+ voltage under

60.5KVdc and well seal it with A+B glue or equivalent, which you can not move away with one screw driver.

7. Before returnin g a serviced display to the customer, a thorough safety test must be performed to verify that the

display is safe to operate without danger or shock. Always perform an AC leakage current check on the exposed metallic parts of the cabinet, such as screw heads. Test method for current leakage is described as follow. (a) Plug the AC line cord directly into rated AC outlet (do not use a line isolation transformer during this check). (b) Use an AC voltmeter hav ing 5000 ohms per volt or with more sensitivity in the following manner: Conn ect a

(c) Reverse the AC plug at the AC outlet and repeat AC voltage measurements for each exposed metallic part. (d) Voltage measured must not exceed 0.5 volts RMS. This corresponds to 0.35 milliamp AC. Any value

2-2 PRODUCT SAFETY NOTICE

Many electrical and mechanical parts in this chassis have special safety visual inspections and the protection afforded by them cannot necessarily be obtained by using replacement components rated for higher voltage, wattage, etc. Before replacing any of these components read the parts list in this manual carefully. The use of substitute replacement parts which do not have the same safety characteristics as specified in the parts list may create shock, fire, X-RAY radiation or other hazards.

2-3 SERVICE NOTES

1. When replacing parts or circuit boards, clamp the lead wires around terminals before soldering.

2. When replacing a high wattage resistor (more than 1/2W of metal oxide film resistor) in circuit board, keep the

resistor about 10mm (1/2 in) away from circuit board.

3. Keep wires away from high voltage or high temperature components.

4. Keep wires in their orig inal position so as to reduce interference.

” means safety relative parts. The use of substitute replacement parts which do not have the same

1500 ohms 10 Watt resistor, paralleled by a 0.15UF, AC type capacitor between a known good earth ground (water pipe, conduit, etc.) and the exposed metallic parts simultaneously. Measure the AC voltage across the combination of 1500 ohms resistor and 0.15UF capacitor.

exceeding this limit constitutes a potential shock hazard and must be corrected immediately.

2-4 HIGH VOLTAGE WARNING

Operation of monitor outside of cabinet or with back removed may cause a serious shock hazard. Work on this model should only be performed by those who are thoroughly familiar with precautions necessary when working on high voltage equipment. Exercise care when servicing this chassis with power applied. Many B plus and high voltage terminals are exposed which, if carelessly contacted, can cause serious shock or result in damage to the chassis. Maintain interconnecting ground lead connections between chassis and picture tube dag when operating chassis. Certain HV failures can increase X-ray radiation. Monitor should not be operated with HV levels exceeding the specified rating for the chassis type. The maximum operating HV specified for the chassis used in this monitor is

25.0KV ± 0.3KV

with a line voltage of 100/240 VAC. Higher voltage may also increase possibility of failure in HV supply. It is important to maintain specified values of all components in the horizontal and high voltage circuits and anywhere else in the monitor that could cause a rise in high voltage or operating supply voltages. No changes should be made to the original design of the monitor. Components shown in the shaded areas on the schematic should be replaced with exact factory replacement parts. The use of unauthorized substitute parts may create a shock, fire or other hazard. To determine the presence of high voltage, use an accurate, high impedance, HV meter connected between second anode lead and CRT dag grounding device. When servicing the High Voltage System, remove static charge from it by connecting a 10K ohm resistor in series with an insulated wire (such as a test probe) between picture tube dag and 2nd anode lead.(AC line cord disconnected from AC power outlet.) The picture tube used in this monitor employs integral implosion protection. Replace with tube of the same type number for continue safety. Do not lift picture tube by the neck. Handle the picture tube only after discharging the high voltage completely.

3. OPERATING INSTRUCTIONS

This procedure gives you instructions for installing and using the 7K color display.

1. Position the display on the desired operation and plug the power cord into a convenient AC outlet. Three-wire

power cord must be shielded and is provided as a safety precaution as it connects the chassis and cabinet to the electrical conduit ground. If the AC outlet in your location does not have provisions for the grounded type plug, the installer should attach the proper adapter to ensure a safe ground potential.

2. Connect the 15-pin color display shielded signal cable to your signal system device and lock both screws on the

connector to ensure firm grounding. The connector information is as follow:

PIN NO.

DESCRIPTION

1. RED 9. NC

2. GREEN 10. GND

3. BLUE 11. SYNC. GND

4. GND 12. SDA

5. GND 13. HORIZ. SYNC

6. GND-R 14.

7. GND-G 15. SCL

8. GND-B

3. Apply power to the display by turning the power switch to the "ON" position and allow about thirty seconds for

display tube warm-up. The Power-On indicator lights when the display is on.

4. With proper signals feed to the display, a pattern or data should appear on the screen, adjust the brightness and

contrast to the most pleasing display.

5. This monitor has power saving function following the VESA DPMS. Be sure to connect the signal cable to the PC.

6. If your 7K Series color display requires service, it must be returned with th e power cord.

11 15

15 - Pin Color Display Signal Cable

PIN NO.

DESCRIPTION

VERT. SYNC (

VCLK)

4. ADJUSTMENT

4-1 ADJUSTMENT CONDITIONS AND PRECAUTIONS

1. Approximately 30 minutes should be allowed for warm up before proceeding.

2. Adjustments should be undertaken only on those necessary elements since most of them have been carefully preset at the factory.

4-2 MAIN ADJUSTMENTS

NO. FUNCTION LOCATION DESIGNATION

1. HV ADJ PCB - MAIN VR703

2. 180V ADJ PCB - MAIN VR902

3. SCREEN ADJ FLY BACK TRANS T402

4. FOCUS ADJ FLY BACK TRANS T402

5. ABL ADJ PCB - MAIN VR701

6. SUB-BRIGHTNESS ADJ PCB - MAIN VR702

FUNCTION ADJ -MENU

-UP

-DOWN PCB - MAIN SW6

-EXIT

4-3 ADJUSTMENT METHOD

1. 180V, Sub-Brightness & HV voltage adjustment:

A. Chroma-2000 Signal generator or PC equivalent set mode 1, VGA 1024X768 pattern 1.0. B. Connect a DC Volt meter between D918 cathode and ground, then adjust VR902 to be 180VDC. C. Connect an accurate,high impedance,HV meter between second anode lead and CRT dag grounding device. Then

adjust VR703 to be 25.0KVDC.

D. Connect a DC Volt meter between TP701(G1) and ground, Brightness set to cen ter and contrast set to max. Then

adjust VR702 to be -10 VDC.

E. Connect a 20kΩ resistor in parallel with R403 to increase the HV, the hold down circuit will operate and the

display will disappear. Then disconnect this resistor to bring the unit to normal condition.

2. Factory preset Timings Adjustment:

A. Press MENU Key to show OSD window press Up or Down Key to switch the functional controls. B. Press the Up Key to select the "ZOOM" function, then press the MENU Key. While do not release the MENU Key

until the OSD window changed to the Factory preset window.

C. The Factory preset window contains the following func tional controls. Select one of the controls. Then press the

Up/Down Key to adjust it's value for the optimum picture. D. Press MENU Key to Quit the OSD window. Mean while the new setting data will be saved in the memory. E. To switches the input signal to the other Timing Mode. Please follow step C ~ D to get the optimum picture.

PCB - MAIN SW4

PCB - MAIN SW5

PCB - MAIN SW7

F. Select the "

" RETURN function and press the MENU Key, then the Factor Preset window will be returned

to the original OSD window.(user's operating condition)

G. The setting data of the CONTRAST, BRIGHTNESS, PIN-BALANCE, PARALLELOGRAM, ROTATION,

COLOR TEMPERATURE are common mode saved in the memory. Don't needed adjust it individual at every

timing Mode and save in the memory.

Model select: for factory only, service engineer can't changed.

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６５００

９３００



FH :68.7KH z

　　Ｒ

Ｇ　Ｂ

Ｒ

FV :85.0Hz

CONTRAST

BRIGHTNESS

H-CENTER

H-SIZE

V-CENTER

V-SIZE

ZOOM

Top corner

Bottom corner

9300

H-MOIRE REDUCE

V-MOIRE REDUCE(No use)

R-GAIN

G-GAIN

B-GAIN

R-BIAS

G-BIAS

B-BIAS

COLOR TEMPERATURE

G B

R G B

PINCUSHION

TRAPEZOID

PIN-BALANCE

PARALLELOGRAM

ROTATION

Sub V-size

Sub V-center

H-Convergence

V-Convergence

Exceed Frequency

Used time

6500

HS HP

SB BI

COLOR TEMPERATURE

DEGAUSS

OSD EXIT

RETURN

Vs Linear

Vc Linear

H-SIZE (NO use)

Max H-SIZE

Moire Disable

Super Brightness Quality

Burn In

3. White Balance, Luminance adjustment: A. Bias (Low Luminance) adjustment:

(a) Set mode 5 1024×768 Fh: 68.6KHz full white pattern. (b) To make the adjustment condition is under the Factory preset window.

Same as step 2-C.

Y= 0.18 ± 0.03cd/m

(e) Make the setting value of B-Bias

50DAC, then adjust FBT screen G2 VR and th e R.B. Bias individual to the color temperature x= 260 ± 10, y= 290 ± 10,Y=0.18±0.03cd/m

set to center. Contrast set to max. raster pattern, then adjust FBT screen G2 VR to make

and R-Bias to 20DAC, keep the value of G-BIAS to

(f) Select OSD function to the 9300°K and 6500°K function individually, then press the MENU Key to make the

setting data saved in the memory.

B. Gain (High light) adjustment:

(a) Set mode 5 1024×768 Fh: 68.6KHz 1/3 white area(100mmX100mm Window). (b) Brightness set to 50DAC and set the contrast to max.

10,Y=140 ±10cd/m

, B-Gain , R-Gain , to make color temperature x=283 ± 10, y=297 ±

C. Select OSD function to the 9300°K function, then press the MENU Key to make the setting data saved in the

memory.

D. The adjustment of 6500°K white Balance may follow step B ~ C , with the x=313 ± 10, y=329 ± 10, Y=140

±10cd/m

. E. Selet “SB” Function to ON. F. The adjustment of 9300°K(SBQ) white blance may follow B~C with the x=283±10, y=297±10,Y≥280cd/m

G. The adjustment of 6500

K (SBQ) white Balance, May follow B~C with the x=313±10,y=329±10 Y≥260cd/m2 .

H. Select “SB” function to OFF and Exit factory preset model.

I. Full white luminance:

(a) Set mode 2 640×480 Fh: 68.6KHz full white pattern. (b) Image Size : H:310±4mm V:232.5±4mm. (c) Brightness set to 50 DAC and set the contrast to max. (d) Adjust VR701 to the luminance at 105±5cd/m

4. Focus Adjustment:

A. Set mode5 1024×768 Fh: 68.6KHz with character full page. B. Adjust brightness to center and contrast to max. C. Then adjust focus VR1 to a fine vertical line. D. Adjust focus VR2 to a fine horizontal line. E. Repeat step C & D..

5. Purity Adjustment A. Be sure that the display is not being exposed to any external magnetic fields. B. Ensure that the spacing between the Purity, Convergence, Magnet, (PCM), assembly and the CRT stem is

29mm .(See below diagram)

C. Produce a complete, red pattern on the display. Adju st the purity magnet rings on the PCM assembly to obtain a

complete field of the color red. This is done by moving the two tabs in such a manner that they advance in an opposite direction but at the same time to obtain the same angle between the two tabs, which should be approximately 180'.

D. Check the complete blue and complete green patterns to observe their respective color purity. Make minor

adjustments if needed.

RELATIVE PLACEMENT OF TYPICAL COMPONENTS

Purity Magnets

6-pole Convergence Magnets

4-pole Convergence Magnets

Deflection Yoke

6. Convergence adjustment

A. Produce a magenta crosshatch on the display. B. Adjust the focus for the best overall focus on the display.

Also adjust the brightness to the desired condition.

C. Vertical red and blue lines are converged by varying the angle between the two tabs of the 4 pole magnets on the

PCM assembly. (See above diagrams)

D. Horizontal red and blue lines are converged by varying the two tabs together, keeping the angle between them

constant. E. Produce a white crosshatch pattern on the display. F. Vertical green and magenta lines are converged by varying the angle between the two tabs of the 6-pole magnets. G. Horizontal green and magenta lines are converged by varying the two tabs together, keeping the angle between

them constant.

5. CIRCUIT DESCRIPTION

5-1 MICRO CONTROLLER CIRCUIT

MICRO Controller

The IC101 contains a 6502 8-bit CPU core, 256 bytes of RAM, 16K bytes of ROM,14 channel 8 bit PWM D/A converters, 2 channel A/D converters for key detection, one 8 bit pre-loadable base timer, internal H-sync and V-sync signals processor providing mode detection, watch- dog timer preventing system from abnormal operation, and an I interface.

C bus

H/V sync signals processor

The functions of the sync processor include polarity detection, H-SYNC & V-SYNC signals counting, Programmable SYNC signals output, free running signal generator,and composite sync separation Pin41/Pin42 are for the H-SYNC and V-SYNC input, Pin33/Pin34 will output the same signal as input sync signal without delay, an d the polarity are setting in the positive. When no signal input, the Pin33 will output a 61HZ V-SYNC free run signal. The Pin34 will output a

62.5KHz H-SYNC free run signal. for the monitor testing use.

On Screen Display Controller

The IC802 on video board is designed for display the built-in characters or fonts onto monitor screen. The display operation is by transforming data and control information from micro controller to RAM through a serial data interface. Pin2 is used to control the internal oscillator frequency by DC voltage input from external low pass filter (R830, C817, R833) and filter (R832, C818) is used to regulate the appropriate bias current for internal oscillator the resonate at specific dot frequency. Pin5 is input the horizontal fly back pulse, for PLL generator tracking. Pin6 is left floating, I

C bus is enabled. Otherwise the SPI bus is enabled. Pin7 the external data transfer through this pin to internal display registers and control registers Pin8 the clock-input pin is used to synchronize the data transfer. Pin10 is input the vertical flyback pulse for synchronizing the vertical position. Pin12 is output a blanking signal to cut off external R.G.B signals of VGA while this chip is displayin g characters or windows. Pin13, Pin14, Pin15 is used to output the OSD (B.G.R) video signal.

5-2 DEFLECTION CIRCUIT

The deflection circuit is achieved by a high performance and efficient solution IC401 (TDA4856) for this monitor. The concept is fully DC controllable and can be used in applications with a micro-controller solutions. The TDA 4856 provides sync. Processing with full auto sync. capability, a flexible SMPS block and an extensiv e set of geometry control facilities. Further the IC generates the drive waveforms for DC coupled vertical boosters to the TDA 4887PS [ref Page-28].

Horizontal Oscillator

The oscillator is of the relaxation type and requires a capacitor of 10nF C413 at pin 29. The maximum oscillator frequency is determined by a resistor R426 form pin 28 to ground. A resistor R425 from pin27 to pin28 defines the frequency range.

PLL 1 Phase Detector

The phase detector is a standard one using switched current sources. It compares the middle of H-sync. with a fixed point on the oscillator saw-tooth voltage. The PLL loop filter C411, R424, C412 is connected to Pin26.

PLL2 Phase Detector

This phase detector is similar to the PLL1 detector and compares the line flyback pulse at pin 1 with the oscillator sawtooth voltage. The PLL2 detector thus compensates for the delay in the external H-deflection circuit by adjusting the phase of the HDRV output pulses. The phase between H-flyback and H-sync can be controlled at pin30.

X-ray Protection

The X-ray protection input pin2 provides a voltage detector with a precise threshold. If the voltage exceeds this threshold for a certain time, an internal latch switches the whole IC into protection mode. In this mode several pins are forced into defined states: Pin8 (HDRV) is floating Pin6 (BDRV) is floating Pin12, 13 ( VOUT 1, 2) are floating Pin16 (CLBL) provides a continuous blanking signal.

Vertical Oscillator

The vertical free –running frequency is determined by the resistor R602 at pin23 and capacitor C602 at pin24. Usually the free-running frequency should be lower than the minimum trigger frequency.

5-3 PFC CIRCUIT

Between rectifier and loading, it is connected a DC-DC switch transformer .Through input current Ii wave following AC input sinusoid voltage wave, Ii may approach sine wave, and input THD may less than 5%,power factor may improve more 0.9. IC905 is used for power factor correction . Q910 is DC-DC power switch transistor, and R955

R956 is used as

divider.

5-4 TRANSISTOR & DIODE CIRCUIT

LOCATION

FUNCTION AL DESCRIPTION

D101 For C103 Discharge Q101 For LED Indicator Control D411 Speed up for Q410 D412 Damping Diode Q405 HDRV Mute Control Q409 Horizontal Driver Q410 Horizontal Out Put Q413 Horizontal Linearity Correction Control Q415~ Q419 Horizontal S-Correction Control Q429~ Q433 Horizontal S-Correction Control D705 Buffer Diode D701 Rectifier for 250V Supply D702 Protection Diode for Q701 D703,D704 Rectifier for -200V Supply Q707 Picture Mute Control AMP Q705, Q706 Brightness Control CKT Q701 Vertical Dynamic Focus Control AMP BD901 Bridge Rectifier for AC Source D909 Rectifier for Start Power Supply D907 Clip Diode for Snubber CKT D906 IC901 VCC Supply D910 Speed UP for Q901 D911 Synchronous Trigger for Power Supply D912,D913,D918 Rectifier for 180V Output Voltage Supply D916,D917,D924 Rectifier for 6.5V,16V,-10V Output Voltage Supply D914 , D901 Rectifier for 80V Output Voltage Supply D409, D410 Raster Position Control D905 Clip Diode for Snuffer Pulse ZD901 Protection Diode ZD902 Protection Diode ZD903 Protection Diode

LOCATION

FUNCTION AL DESCRIPTION

Q901 MOS FET for Switching Power Control Q904 Start up CKT for IC901 Q912, Q913 To Turn 6.3V Supply Off when the Off Mode is Required Q908, Q909 To Turn 16V Supply Off when the Off or Suspend Mode is Required Q408 MOS FET for B+ Control Q406, Q407 Push Pull Driver for Q408 D856 ~ D858 DC Restoration for CRT Bias Adjustment D850 , D852,D854 Protection Diode for Q801, Q802, Q803. Q850 ~ Q852 DC Restoration for CRT Bias Adjustment

6.TROUBLE SHOOTING CHART

6-1 NO RASTER, CRT RELATIVE CIRCUIT PROBLEMS

CHECK MAIN PCB POWER SUPPLY

POWER SUPPLY 180V,16V,80V

60.5V, 14.5V, 80V

CHECK MAIN PCB

CHECK THE HIGE VOLTAGE OF

CHECK THE HIGE VOLTAGE

CRT ABOUT 25±0.3KV OR Q409

OF CRT ABOUT 25.5 ~ 26.5KV

DRAIN PIN VOLTAGE WAVE

CHECK THE VOLTAGE OF CRT

HEATER ABOUT 6.3V

CHECK SCREEN VOLTAGE

CHECK SCREEN VOLTAGE ABOUT

ABOUT 500V TO 800V

400V TO 700V

LESS THAN 300V

CHECK POWER SAVING CIRCUIT, H-SYNC, V-SYNC SIGNAL

REFER ITEM S.M.P.S.

CHECK FAILSAFE CKT IC401 PIN 2 RELATIVE CKT.

CHECK CRT'S HEATER RELATIVE CIRCUIT

CHECK FBT

BRIGHTNESS SET TO MAX. THEN CHECK CRT G1 VOLTAGE

CHECK BRIGHTNESS CIRCUIT

CHECK VOLTAGE OF THE CRT

CATHODE ABOUT 60V TO 70V

CHECK BRIGHTNESS CIRCUIT

Q705,Q706, RELATIVE CKT.

Q703, Q706, Q707 RELATIVE CKT.

REFER ITEM 6-2 “ABNORMAL

REFER ITEM 8-2 "ABNORMAL DISPLAY"

DISPLAY”

2.ABNORMAL VIDEO LEVEL ON SCREEN

HECK THE VOLTAGE OF IC801

CHECK THE VOLTAGE OF IC801

PIN 6, 9, 22 ABOUT 12V

PIN7,15,18,21

CHECK THE SIGNAL INPUT OF R.G.B. ABOUT 0.7Vpp

CHECK IC801 PIN5

CHECK IC801 PIN 15 CLAMP PULSE

CLAMP PULSE PI

PIN 16 BLANK PULSE

CHECK THE VIDEO OUTPUT OF

CHECK THE VIDEO OUTPUT OF IC801 PIN 18, 20, 23 ABOUT 4Vpp,

CONTRAST SET MAX.

R.G.B. APPROACH STANDARD

11 BLANK PULSE

IC801 PIN16,19,22 ABOUT

4Vpp,CONTRAST SET MAX.

CHECK 12V RELATIVE CIRCUIT

CHECK SIGNAL CABLE OR INTERFACE CARD.

CHECK THE IC105 RELATIVE CIRCUIT

IC401 PIN16 OUTPUT

OR IC401 PIN 16 OUTPUT

CHECK IC801 PIN 13 ABOUT 4V PIN 26, 27, 28 ABOUT 4V OR

CHECK IC801 PIN24 ABOUT

CHECK Q801 AND RELATIVE CKT

3. ABNORMAL DDC (PLUG & PLAY)

CHECK IC101 PIN 5 VOLTAGE ABOUT 5V

CHECK SIGNAL CABLE OR H802 PIN 3, 4 DATA OUTPUT

CHECK Q102 GOOD OR FAIL

6-2 ABNORMAL DISPLAY

1.NO SIGNAL ON SCREEN

CHECK VIDEO IC801 VCC ABOUT 12V

CHECK THEOUTPUTVOLTAGE

CHECK THE OUTPUT VOLTAGE

OF IC801 PIN16,19,22 ABOUT 3Vpp

OF IC801 PIN 18, 20, 23 ABOUT 3Vpp

CHECK THE B+ VOLTAGE OF VIDEO PCB ABOUT 80V

CHECK THE VOLTAGE OF CRT CATHODE ABOUT 40Vpp

CHECK THE VOLTAGE OF FBT

CHECK THE VOLTAGE OF FBT SCREEN

SCREEN ABOUT 500V TO 800V

ABOUT 400V TO 700V

CHECK THE 12V PIN OF P802 CONNECTOR

CHECK THE RELATIVE CIRCUIT OF IC801

CHECK THE 80V RELATIVE CIRCUIT OF SMPS ON MAIN PCB

CHECK THE IC803 PIN1,2,3

CHECKTHE VQ802 ~ Q807

OUTPUT RELATIVE CIRCUIT

RELATIVE CIRCUIT

LESS THAN 500V

LESS THAN 400V

EXCEED 700V

CHECK FBT RELATIVE CIRCUIT

CHECK FBT & CRT RELATIVE CIRCUIT OR REFER ITEM 7-1

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