Tatung VM7K9 Schematic

Model VM7K9

(With PFC)

SERVICE INFORMATION

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 7G SERIES COLOR MONITOR

R

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, Recall, Degaussing, Color
Temperature, Volume. (For 7KlrA Model)

5. Input Video Signal

Mode 1 Mode 2 Mode 3 Mode 4 Mode 5 Mode 6

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

Negative Negative Negative Negative Positive Positive

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

Positive Negative Negative Negative Positive Positive

Horizontal: 640 (H) 720 (H) 640 (H) 640 (H) 800 (H) 800 (H)
Vertical : 480 (V) 400 (V) 480 (V) 480(V) 600(V) 600 (V)
Fh (kHz): 31.47 31.47 37.5 43.3 46.875 53.67
Fv (Hz) : 60 70 75 85 75 85

Mode 7 Mode 8 Mode 9 Mode 10 Mode 11 Mode 12
RGB Analog RGB Analog RGB Analog RGB Analog RGB Analog RGB Analog

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

Positive Positive Positive Positive Positive Positive

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

Positive Positive Positive Positive Positive Positive

Horizontal: 1024 (H) 1024 (H) 1280 (H) 1280 (H) 1280 (H) 1600 (H)
Vertical : 768 (V) 768 (V) 960 (V) 1024 (V) 1024 (V) 1200 (V)
Fh (kHz): 60.02 68.6 85.9 79.6 91.1 93.8
Fv (Hz) : 75 85 85 75 85 75

6. Display Size
Horizontal: 300 mm
Vertical: 230 mm

7. Scanning Frequencies
Horizontal:
Vertical:

8. Factory Preset Timings: 8
User Timings: 10

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

10. Video Bandwidth: 200 MHz

GB Analog RGB Analog RGB Analog RGB Analog RGB Analog 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: 0℃ to 40℃ Ambient

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

•

Weight: 17.0 Kgs(Net), 20.5Kgs(Gross) for 7Glr

14

17.8 Kgs(Net), 21.5Kgs(Gross) for 7GlrA

15 Dimensions Monitor:

Carton:
Monitor:

540(W) × 532(H) × 570(D) mm
410(W)

×

411(H)

×

430(D) mm for 7Glr

410(W) × 448(H) × 430(D) mm for 7GlrA

16. External Connection :

15 Pin D-type Connector AC Power Cord

17. Speaker: (for 7KlrA only)
Rate power: 5W (per channel)
Impedance:

8Ω

18. Regulations: UL, CSA, FDA, FCC, TÜV/GS, CE, MPR-II
TCO’95 (for 7KlrA only)

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 the picture tube in any manner unless shatter-proof 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. Before returning 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 having 5000 ohms per volt or with more sensitivity in the following manner:

Connect a 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.

(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

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

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 original position so as to reduce interference.

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

26KV ± 1KV

with a line voltage of 120/240 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. Three­wire 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 the power cord.

1

6

11 15

5

10

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. 14.5V ADJ PCB - MAIN VR901

2. B + 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

-UP

7. FUNCTION ADJ -DOWN

4-3 ADJUSTMENT METHOD

1. 14.5V, B + & HV voltage adjustment:
A. Chroma-2000 Signal generator or PC equivalent set mode 1, VGA 640X480 pattern 1.0 .
B. Connect a DC Volt meter between TP901 or D922 cathode and ground, then adjust VR901 to be 14.5VDC.
C. Connect a DC Volt meter between TP902 or D925 cathode and ground, then adjust VR902 to be 60.5 VDC.
D. Connect a DC Volt meter between TP701(G1) and ground, Brightness set to max. Then adjust VR702 to

be -50 VDC.

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 functional controls. Select one of the controls. Then

press the Up/Down Key to adjust it's value for the optimum picture.

-MENU

-EXIT

2

PCB - MAIN SW103

PCB - MAIN SW105

PCB - MAIN SW104

1

PCB - MAIN SW102

FACTORY PRESET

H: 36.51kHz

V: 51.34Hz

VcVs

9300

6500

Tm

080

H-MOIRE REDUCE

V-MOIRE REDUCE

R-GAIN

G-GAIN

B-GAIN

R-BIAS

G-BIAS

R-BIAS

COLOR TEMPERATURE

CONTRAST

BRIGHTNESS

H-CENTER

H-SIZE

V-CENTER

V-SIZE

ZOOM

Top corner

Bottom corner

9300

Vs
Vc

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.

F. Select the "

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

PINCUSHION

TRAPEZOID

PIN-BALANCE

PARALLELOGRAM

ROTATION

Sub V-size

Sub V-center

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

6500

COLOR TEMPERATURE

DEGAUSS

OSD EXIT

RETURN

Vs Linear

Vc Linear

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.

H

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

B. Gain (High light) adjustment:

C. Recheck item A&B to make sure both of them in spec. Finally select OSD function to the 9300°K function,

D. The adjustment of 6500°K white Balance, May follow step A ~ C , with the x=313 ± 10, y=329 ± 10.
E. Full white luminance:

4. Focus Adjustment:
A. Set mode 2 640×480 Fh: 31.5KHz 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

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

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

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

(a) Set mode 2 640×480 Fh: 31KHz full white pattern.
(b) To make the adjustment condition is under the Factory preset window.

Same as step 2-C.

(c) Warm up more than 20 minutes.

(d) Brightness

VR to make Y= 1.0FL ± 0.2FL

(e) Brightness set to raster just cutoff, adjust contrast to be 4FL, then adjust G-Bias

R-Bias
temperature x= 281 ± 10, y= 311 ± 10.

(a) Set mode 2 640×480 Fh: 31.5KHz full white pattern.
(b) Brightness set to raster just cutoff and set the contrast to max.

(c) Adjust G-Gain

10.

then press the MENU Key. To make the setting data saved in the memory.

(a) Set mode 2 640×480 Fh: 31.5KHz full white pattern.
(b) Image Size : H:300±4mm V:230±4mm.
(c) Brightness set to raster just cut off and set the contrast to max.
(d) Adjust VR701 to the luminance at 30 FL ± 2FL.

29mm .(See below diagram)

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'.

adjustments if needed.

set to maximum. Contrast set to min. full white pattern, then adjust FBT screen

, B-Bias ,

, to make the setting value is(20), then adjust the R.G.B Bias individual to the color

, B-Gain , R-Gain , to make color temperature x=281 ± 10, y=311 ±

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 V­sync signals processor providing mode detection, watch- dog timer preventing system from abnormal operation,
and an I2C bus interface.

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. Pin39/Pin40 are for the H-SYNC and V­SYNC input, Pin32/Pin33 will output the same signal as input sync signal without delay, and the polarity are
setting in the positive. When no signal input, the Pin32 will output a 61HZ V-SYNC free run signal. The Pin33
will output a 62.5KHz H-SYNC free run signal. for the monitor testing use.

On Screen Display Controller

The IC103 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 (R125,
C114, R161) and filter (R126, C115) 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, I2C 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 displaying 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 IC 401 (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 extensive
set of geometry control facilities. Further the IC generates the drive waveforms for DC coupled vertical boosters to
the TDA 4866 [ref Page-28].

Horizontal Oscillator

The oscillator is of the relaxation type and requires a capacitor of 10nF C403 at pin 29. The maximum oscillator
frequency is determined by a resistor R403 form pin 28 to ground. A resistor R402 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 c401, R401, C402 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
saw-tooth 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 R608 at pin23 and capacitor C604 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.IC 902 is controled by power factor correction.Q904 is DC-DC power switch
transistor, R916,R195 is used as divider.

5-4 TRANSISTOR & DIODE CIRCUIT

LOCATION

D101 For C102 Discharge

Q101 For LED Indicator Control

D418 Protection Diode for Snubber Clip Diode ZD401

D431 Protection Diode for B+ Control

D405, D424 Speed up for Q403

D406, D407 Supply a bias for D408

D408 Damping Diode and Modulation Diode

Q416 B+ MUTE

D414~ D417,D419 Buffer Diode for IC403

D421 ~ D423 Detected for Q406

Q401 B+ Mute Control

Q402 Horizontal Driver

FUNCTION AL DESCRIPTION

Q403 Horizontal Out Put

Q404, Q406 A differential Amp for Drive Q405

Q405 DarlingtonTransistor for H-Size Control

Q407 Horizontal Linearity Correction Control

Q410, Q412, Q417 Horizontal S-Correction Control

Q418, Q420 Horizontal S-Correction Control

ZD601,ZD602 VF Voltage Divider

D707 Mixing Diode

D703 Buffer Diode

D704 Rectifier for 250V Supply

D705 Protection Diode for Q708

LOCATION

D706,D708 Rectifier for -200V Supply

Q707 Picture Mute Control AMP

Q703, Q706 Brightness Control CKT

Q708 Vertical Dynamic Focus Control AMP

D901 ~ D904 Bridge Rectifier for AC Source

D909 Rectifier for Start Power Supply

D910 Clip Diode for Snubber CKT

D911 IC901 VCC Supply

D913 Speed UP for Q901

D914 Synchronous Trigger for Power Supply

D918 ~ D919 Rectifier for Output Voltage Supply

D921 ~ D923 Rectifier for Output Voltage Supply

D924 Clip Diode for Trigger CKT

FUNCTION AL DESCRIPTION

D925 Rectifier for B+ Supply

D926, D927 Raster Position Control

D939 Clip Diode for Snuffer Pulse

ZD901 Protection Diode

ZD902 Protection Diode

ZD903 Protection Diode

Q901 MOS FET for Switching Power Control

Q904, Q906 Start up CKT for IC901

Q908, Q916 To Turn 6.3V Supply Off when the Off Mode is Required

Q909, Q910 To Turn 14.5V Supply Off when the Off or Suspend Mode is Required

Q911 MOS FET for B+ Control

Q912, Q915 Push Pull Driver for Q911

Q914 Pre-Amplifier for Q912, Q915

D817 ~ D819 DC Restoration for CRT Bias Adjustment

D814 ~ D816 Protection Diode for Q808, Q809, Q810, Q811, Q812, Q813

Q801 A.B.L Control

Q817 ~ Q819 DC Restoration for CRT Bias Adjustment

6.TROUBLE SHOOTING CHART

6-1 NO RASTER, CRT RELATIVE CIRCUIT PROBLEMS

CHECK MAIN PCB POWER SUPPLY

60.5V, 14.5V, 80V

NG

OK

CHECK THE HIGE VOLTAGE
OF CRT ABOUT 25.5 ~ 26.5KV

NG

OK

CHECK THE VOLTAGE OF CRT
HEATER ABOUT 6.3V

NG

OK

CHECK SCREEN VOLTAGE ABOUT

400V TO 700V

LESS THAN 300V

OK

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

OK

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

NG

OK

CHECK VOLTAGE OF THE CRT
CATHODE ABOUT 60V TO 70V

NG

CHECK BRIGHTNESS CIRCUIT

Q703, Q706, Q707 RELATIVE CKT.

REFER ITEM 8-2
"ABNORMAL DISPLAY"