Tatung VM9G5DA S995T User manual

COLOUR MONITOR
FLAT SCREEN
VM9G5DA S995T
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 ................................................................................ 6-7
4. ADJUSTMENT ......................................................................................................... 7
4-1 ADJUSTMENT CONDITIONS AND PRECAUTIONS ............................... 7
4-2 MAIN ADJUSTMENTS ................................................................................. 7
4-3 ADJUSTMENT METHOD ............................................................................. 7-10
5. CIRCUIT DESCRIPTION ......................................................................................... 11
5-1 MICRO CONTROLLER CIRCUIT ............................................................... 11
5-2 DEFLECTION CIRCUIT ......…….................................................................. 12
5-3 VIDEO CIRCUIT ............................................................................................ 12
5-4 POWER SUPPLY .....……………………....................................................... 12
5-5 TRANSISTOR & DIODE CIRCUIT .....……………….................................. 13-15
6. TROUBLE SHOOTING CHART .............................................................................. 16
6-1 NO RASTER, CRT RELATIVE CIRCUIT PROBLEMS .............................. 16
6-2 ABNORMAL DISPLAY ................................................................................. 17
6-3 NO BLANKING .............................................................................................. 18
6-4 HOR. /OSC /DEF /HV CIRCUIT FAULT ...................................................... 18
6-5 ABNORMAL DDC (PLUG & PLAY) ...........…………................................. 19
6-6 ABNORMAL HORIZONTAL DEFLECTION .............................................. 19
6-7 ABNORMAL VERTICAL SCANNING ........................................................ 20
6-8 SIDE-PIN CUSHION DISTORTION ............................................................. 20
6-9 POOR FOCUS ................................................................................................ 20
6-10 NO SOUND (OPTION FOR AUDIO MODEL ONLY).........….................... 21
6-11 ABNORMAL VIDEO LEVEL ON SCREEN................................................. 21
6-12 POWER SUPPLY TROUBLE SHOOTING CHART ..................................... 22
7. MECHANICAL OF CABINET FRONT DIS-ASSEMBLY...................................... 23
8. PARTS LISTING .........................................................................................…............ 24
9. BLOCK DIAGRAM .................................................................................................. 45-46
10. IC BLOCK DIAGRAMS............................................................................................ 47-49
11. PCB LAYOUT .......................................................................................................... 50-51
12. SCHEMATIC DIAGRAM ......................................................................................... 52

1. SPECIFICATIONS
1. CRT
48.3 CM(19") 90degree Deflection, 29mm Neck, 0.26mm Dot Pitch, Non-Glare Screen,anti-reflective,antistate
coating
2. Viewable image Size : 45.7CM (18") 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
(Option).
5. Input Video Signal
Mode 1 Mode 2 Mode 3 Mode 4
RGB Analog RGB Analog RGB Analog RGB Analog
Horiz. Sync: TTL Level TTL Level TTL Level TTL Level
Negative Negative Positive Positive
Vert. Sync: TTL Level TTL Level TTL Level TTL Level
Negative Positive Positive Positive
Horizontal: 640 (H) 720 (H) 800 (H) 1024 (H)
Vertical : 480 (V) 400 (V) 600(V) 768 (V)
Fh (KHz): 31.47 31.47 46.875 60.02
Fv (Hz) : 60 70 75 75
Mode 5 Mode 6 Mode 7 Mode 8
RGB Analog RGB Analog RGB Analog 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) 1024 (V) 1024 (V) 1200 (V)
Fh (KHz) : 68.6 79.97 91.15 93.75
Fv (Hz) : 85 75 85 75
6. Display Size
Horizontal: 346 mm
Vertical: 260 mm
7. Scanning Frequencies
Horizontal: 30KHz ~95KHz
Vertical: 50 Hz ~150 Hz

8. Factory Preset Timings: 8
User Timings: 20
9. Misconvergence
Center : 0.25mm Max.
Corner : 0.35 mm Max.
10. Video Dot Rate: 200 MHz
11. Power Source:
Switching Mode Power Supply
AC 100 ~240V, 50/60Hz Universal Type
12. Operating Temperature: 0°C to 40°C Ambient
13. Humidity:
10%to 85%Relative, Non-Condensing
14. Weight: 20.0 Kgs(Net), 24.0Kgs(Gross)
21.8 Kgs(Net), 24.8Kgs(Gross) (for Audio model)
15. Dimensions Monitor:
Carton: 574(W) x 537(H) x 594(D) mm
Monitor: 460(W) x 466(H) x 470(D) mm
460(W) x 503(H) x 470(D) mm (for Audio model)
16. External Connection:
15 Pin D-type Connector
AC Power Cord
17. Speaker: (Option)
Rate power: 5W (per channel)
Impedance: 16Ω
18. Regulations: UL, CSA, FDA, FCC, TÜV/GS, and CE, MPR-II
TCO'95 or TCO'99(Option)

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
26.5KV ±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 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 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:
3.
1
6
11 15
5
10
15 - Pin Color Display Signal Cable

PIN NO. DESCRIPTION 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. VERT. SYNC (•VCLK)
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 color display requires service, it must be returned with the power cord.
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. 54V ADJ PCB - MAIN VR902
2. HIGH VOLTAGE ADJ PCB - MAIN VR801
3. SCREEN ADJ FLY BACK TRANS T802
4. FOCUS ADJ FLY BACK TRANS T802
5. ABL ADJ PCB - MAIN VR401
6. SUB BRIGHTNESS ADJ PCB - MAIN VR403
7. SHUTTLE KNOB KEY - BOARD SW103
4-3 ADJUSTMENT METHOD
1. B + & HV voltage adjustment:
A. Chrome-2000 Signal generator or PC equivalent set mode 7, VGA 1024 x768 pattern 1.0.
B. Connect a DC Volt meter between TP 904 and ground, then adjust VR902 to be 54.0 VDC.
C. Connect a DC Volt meter with HV probe 1000: 1 between CRT Anode and ground, Then adjust VR801 to be
26.5KV.
D. Connect a DC Volt meter between TP401 (G1) and ground, Brightness set to 50. Then adjust VR403 to be –
35VDC.

2. Factory preset Timings Adjustment:
A.Press shuttle Knob to show OSD window press shuttle Knob again to switch the functional controls.
B.Rotate the shuttle Knob to select the "ZOOM" function, then press the shuttle Knob 10 seconds again. While do not
release the shuttle Knob until the OSD window changed to the Factory preset window.
C. The Factory preset window contains the following functional controls. Select one of the control. Then press the
shuttle knob to adjust its value for the optimum picture.
80
RGB
RGB
EXIT
FACTORY PRESET
6500
9300
H-SIZE CB CORNER BOTTOM G-GAIN
H-CENTER V-C LINEARITY B-GAIN
V-SIZE V-S LINEARITY R-BIAS
VS V-SUB SIZE ROTATION G-BIAS
V-CENTER H-MOIRE REDUCE G-BIAS
VC V-SUB CENTER V-MOIRE REDUCE 9300 COLOR TEMPERATURE
PINCUSHION DEGAUSS
TRAPEZOID 6500 COLOR TEMPERATURE
PARALLELOGRAM CONTRAST RETURN
PIN-BALANCE BRIGHTNESS OSD EXIT
CT CORNER TOP R-GAIN
D.While the all adjustments are finished, please select the " EXIT " function, and press the shuttle knob to Quit the
OSD window.
E. To switches the input signal to the other Timing Mode. Please follow step C ~ D to get the optimum picture.
F. Select the " " RETURN function and press the shuttle knob, then the Factor Preset window will be returned
to the original OSD window.(user's operation 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.
3. White Balance, Luminance adjustment:
A.Bias (Low Luminance) adjustment:
(a) Set mode 7 1024 x768 Fh: 60KHz 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 30 minutes.
(d) Brightness set to maximum. Contrast set to min. raster pattern, then adjust FBT screen VR to make
Y=1.0FL ±0.2FL
(e) Set G-Bias to make the setting value about 56, then adjust the R. B Bias individual to the color
temperature x= 283 ±10, y= 297 ±10.
(f) Readjust screen VR to y=1.0FL ±0.2FL
B. Gain (High light) adjustment:
(a) Set mode 7 1024 x768 Fh: 60KHz full white pattern.
(b) Brightness set to raster just cutoff and set the contrast to max.
(c) Adjust G-Gain , B-Gain , R-Gain , to make color temperature x=283±10, y=297±10.
C.Recheck item A&B to make sure both of them in spec. Finally select OSD function to the 9300°K function, then
press the shuttle knob. To make the setting data saved in the memory.
D.The adjustment of 6500°K white Balance, May follow step item B , with the x=313±10, y=329±10.
E. Full white luminance:
(a) Set mode 7 1024 x768 Fh: 60K full white pattern.
(b) Image Size : H:346±4mm V:260±4mm.
(c) Contrast set to max, Brightness set to cut off.
(d) Adjust VR401 to the luminance at 28 FL ±1FL.
4. Focus Adjustment:
A. Set mode 7 1024 x768 Fh: 60KHz 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.to make the display focus performance very well.

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. Adjust 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
Deflection Yoke
4-pole Convergence Magnets
6-pole Convergence Magnets
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 code, 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-laudable base timer, internal H-sync and V-sync signals processor
providing mode detection, watch- dog timer preventing system from abnormal operation, and an I2C bus interface.
When CPU detects a timing, it takes relative data from E²PROM (IC102), then output voltage to control the geometry and
video R.G. B drive & bias to make the display best. If key is pressed, the CPU will do some jobs according to the key
function.
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 V-SYNC 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 and filter 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
Hor. Sync. And Ver. Sync come from PC, then go into the CPU (IC101). The output Sync Flows into Auto sync Deflection
Controller IC401 (TDA4856). The IC401 processes Sync Signal and output drive signal to horizontal, vertical and B+ driver
circuit. IC401 also generates some certain waveforms for usage of geometry correction, such as H-size, V-center etc. by DC
current or voltage control. Thus the geometry can be controlled automatically or manually.
IC601 (TDA4866) is a full bridge current driven Vertical deflection booster. R626 connected in series with the deflection
coil provides internal feedback information. The differential input circuit is voltage driven, R629 connected between the
differential input, determines the output current through the deflection coil.
Q424, Q425,Q409,Q411,Q402, T401 are Horizontal drive circuit, Q403 is an H-output transistor. Q404, Q405, Q406, Q407
are Horizontal size control circuit. Q427, RY401 to change retrace time of horizontal, the switch frequency is 66KHz.
IC403, IC404, Q412,Q417,Q420,Q419,Q418 to switch the Cs capacitor. L401 is a linearity correction coil. Q708, T701 are
Hor. And Ver. Dynamic focus circuit.
Q705, Q706 generate the vertical blanking signal output to G1 of CRT, Q703, Q707 are brightness control transistor, Q416
is also for MUTE control.
5-3 VIDEO CIRCUIT
IC801 is a three channel video preamplifier with OSD Mixing, PIN 5, 8, 11 are video input, the signal recommended is equal
to 0.7Vp-p, PIN 1, 2, 3, 4 are OSD signal input. The luminosity of OSD was determined by PIN 25, PIN 15 is clamping
signal input, that to restore the DC voltage of video signal. Video output from pin 18, 20, 23 and couple to the R.G, B,
Amplifier Q802, Q805, Q803, Q806, Q804,Q807, directly,Q817, Q818, Q818, are R.G.B bias control, which to set the black
level.
5-4 POWER SUPPLY
The design uses a discontinuous fly back topology operating in current-mode resulting in a multiple output switcher with
stack well. Faster diodes are used. The fast transient response of the control loop maintains picture integrity. Very fast
current limiting protects the switcher against short circuits.
UC3842AM is the current mode controller selected. It offers feed forward compensation, feedback error amplifier, and low
voltage lock out features, IC901, T901, Q901 are a main power supply circuit, that provide 80V, 54V, 30V, 20V to the
deflection and video circuit, and provide 5V through Q906 to MCU.
The FET starts a cycle by allowing current to flow into the primary of the power transformer. As current ramps up with time,
the voltage across the current sense resistor (R929) also ramps to a point where the UC3842 determine that enough power is
stored and turns off the FET. As the voltage on the transformer reverses, power is dumped from the main power transformer
through diodes into the different supplies. To keep RFI to a minimum and reduce transistor heating, a turn-off snuffer
network is placed across the FET. Current from the secondary windings are rectified and filtered to create the desired
voltages. Small high current capacitors quickly return charging current to the source. Filter inductors remove high frequency
noise.

5-5 TRANSISTOR & DIODE CIRCUIT
LOCATION FUNCTIONAL DESCRIPTION
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 Protection diode for Q403
D406, D407 Supply a bias for D408
D408 Demping diode
D421~D423 Detected for Q405
D414 ~ D417,D419 Buffer diode for IC403, IC404
Q416 B+ Mute
Q401 B+ Mute Control
Q402,Q403 Horizontal output
Q404,Q406 A Differential Amp for Drive for Q405
Q405 Darlington Transistor 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 Driver
D707 Mixing Diode
D703 Buffer Diode
D704 Rectifier for 250v Supply
D705 Protection Diode for Q708
D706,D708 Rectifier for –200V supply
Q707 Picture Mute Control CKT
Q703,Q706 Brightness Control CKT
Q708 Vertical Dynamic Focus Control AMP
D901~D904 Bridge Rectifier for AC Source
D909 Rectifier for Start Power Suppply
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

LOCATION FUNCTIONAL DESCRIPTION
D921~D923 Rectifier for output Voltage Supply
D924 Clip Diode for Trigger CKT
D925 Rectifier for B+ Supply
D926,D927 Raster Position Control
D939 Clip Diode for Snuffer Pulse
ZD901,ZD902,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 Mode 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
NG
OK OK
NG
OK
NG
OK
LESS THAN 500V
OK
NG
OK
NG
CHECK MAIN PCB POWER SUPPLY
60.5V,14.5V,80V
CHECK THE HIGE VOLTAGE
OF CRT ABOUT 25.5 ~ 26.5KV
CHECK POWER SAVING CIRCUIT,
H-SYNC, V-SYNC SIGNAL
REFER ITEM S.M.P.S.
CHECK FAILSAFE CKT IC401
PIN 2 RELATIVE CKT.
CHECK THE VOLTAGE OF CRT
HEATER ABOUT 6.3V
CHECK CRT’S HEATER
RELATIVE CIRCUIT
CHECK SCREEN VOLTAGE ABOUT
400VTO 700V
CHECK FBT
BRIGHTNESS SET TO MAX. THEN
CHECK CRT G1 VOLTAGE
CHECK VOLTAGE OF THE CRT
CATHODE ABOUT 60V TO 70V
CHECK BRIGHTNESS CIRCUIT
Q703,Q706,Q707 RELATIVE CKT.
CHECK CRT

6-2 ABNORMAL DISPLAY
NO SIGNAL ON SCREEN
NG
OK
NG
OK
NG
OK
NG
OK
LESS THAN 400V
EXCEED 800V
6-3 NO BLANKING
NO V.
NO H.
CHECK THE RELATIVE CIRCUIT
OF C433,D410,R635,R636,IC105
ON MAIN PCB
CHECK IC801 Pin16 on Video PCB
CHECK G1 RELATIVE CIRCUIT
Q705, Q718,C707 ON MAIN PCB.
CHECK THE RELATIVE
CIRCUIT OF BLANKING
CHECK VIDEO IC801 VCC ABOUT 12V
CHECK THE OUTPUT VOLTAGE
OF IC701 PIN 18, 20, 23 ABOUT 3Vpp
CHECK THE PIN 2
OF P802 CONNECTOR = 12V
CHECK THE RELATIVE CIRCUIT
OF IC801
CHECK THE B+ VOLTAGE OF
VIDEO PCB ABOUT 80V
CHECK THE 80V RELATIVE CIRCUIT
OF SMPS ON MAIN PCB
CHECK THE VOLTAGE OF CRT
CATHODE ABOUT 40Vpp
CHECK THE VOLTAGE OF FBT
SCREEN ABOUT 400V TO 700V
OF SMPS ON MAIN PCB
CHECK THE R.G.B OUTPUT
RELATIVE CIRCUIT
CHECK FBT RELATIVE CIRCUIT
CHECK FBT & CRT RELATIVE
CIRCUIT

6-4 HOR./OSC/DEF/HV CIRCUIT FAULT
NO RASTER (DISCONNECT WITH SIGNAL CABLE)
NG
OK
NG
OK
NG
OK
NG
6-5 ABNORMAL DDC (PLUG & PLAY)
6-6 ABNORMAL HORIZONTAL DEFLECTION
1. ABNORMAL HORIZONTAL WIDTH OF VIDEO
NG
OK
OK NG
CHECK IC101 PIN5 VOLATAGE ABOUT 5V
CHECK THE COLLECTOR VOLTAGE
OF Q403 ABOUT 1100Vpp AT FH:31KHz
CHECK IC801 PIN 10 ABOUT 11.5V VDC
CHECK IC401 PIN10 RELATIVE
CIRCUIT
CHECK IC801 PIN 26 ~ 30
RELATIVE CIRCUIT
CHECK IC401 PIN8 Waveform ABOUT 10Vpp
CHECK THE DRAIN VOLTAGE
OF
Q
402ABOUT 40V
pp
CHECK Q402, T401
RELATIVE CIRCUIT
CHECK T401, T402, Q402, Q403, D408,
C418, C419,H-DY
READJUST H-WIDTH FUNCTION
CHECK THE HV OF
CRT ABOUT 26KV
CHECK FBT B+ VOLTAGE
ABOUT 60.5V AT FH = 31KHz
CHECK THE RELATIVE CIRCUIT OF
SMPS.Q914, Q915, Q911, Q912
IC801 PIN 3, 4, 5, 6, VR801
CHECK THE RELATIVE CIRCUIT
OF Q404, Q405, & Q406
CHECK SIGNAL CABLE OR H802
PIN3 4 DATA OUTPUT
CHECK Q102 GOOD OR FAIL

2. ABNORMAL HORIZONTAL RASTER CENTER
3.ABNPRMAL HORIZONTAL VIDEO CENTER
4.ABNORMAL HORIZONTAL LINEARITY
6-7 ABNORMAL VERTICAL SCANNING
NG
OK
NG
OK
6-8 SIDE-PIN CUSHION DISTORTION
NG
CHECK T903, D926, D927, R968，P403
CHECK L401,Q407,R447,C448 AND IC101
PIN 20, 21, 22, 23. CS SWITCHER IC403,
READJUST SIDEPIN FUNCTION VALUE
CHECK IC101 ,Q404,Q405,Q406 RELATIVE
CKT
CHECK IC101 PIN9\10,IC401 PIN18\19
READJUST V-SIZE FUNCTION VALUE
CHECK THE IC601 PIN 7 ABOUT 40V
CHECK VERT. OSC CIRCUIT
CHECK ZD601,ZD602, & SMPS
RELATIVE CIRCUIT
CHECK IC601 PIN 7 OUTPUT ABOUT
38V
pp
CHECK IC801, PIN22, 23,24
RELATIVE CIRCUIT
CHECK IC401 PIN12, 13, RELATIVE
CIRCUIT
READJUST V-CENTER
CHECK IC101 PIN9、10，IC401 PIN15、19

6-9 POOR FOCUS
NG
NG
6-10 NO SOUND (OPTION FOR AUDIO MODEL ONLY)
OK
NG
OK
NG
OK
6-11 ABNORMAL VIDEO LEVEL ON SCREEN
NG
OK
NG
OK
NG
OK
NG
OK
READJUST FOCUS CONTROL
CHECK FOCUS CONTROL UNIT,FOCUS
LEAD WIRE, CRT SOCKET & CRT
ADJUST VOLUME CONTROL
ENSURE THE SOUND SOURCE
IS POWER ON
CHECK IC501
PIN 14 ABOUT 14V
ENSURE THE SOURCE CABLE
CONNECTION
CHECK POWER
SUPPLY CIRCUIT
CHECK IC501
IC501 FAILURE
SPEAKER FAILURE
CHECK THE VOLTAGE OF IC801
PIN6,9,22ABOUT12V
CHECK THE SIGNAL INPUT OF
R
.G.
B
.
AB
OU
T 0
.7Vpp
CHECK 12V RELATIVE CIRCUIT
CHECK IC801 PIN 15\PIN16
CLAMP PULSE ABOUT 5V
pp
.
CHECK SIGNAL CABLE OR
INTERFACE CARD.
CHECK THE VIDEO OUTPUT OF
IC801 PIN 18, 20, 23 ABOUT 4Vpp
CONTRAST SET MAX.
CHECK IC501RELATIVE CKT OR
IC401 PIN 16 OUTPUT
R.G.B. APPROACH STANDARD
CHECK IC801 PIN 13 ABOUT 4V
PIN 26, 27, 28 ABOUT 4V OR
CHECK Q801 CKT.

6-12 POWER SUPPLY TROUBLE SHOOTING CHART
BEFORE CHECK SW.REG. PLEASE REFER TO THE POWER SUPPLY BLOCK DIAGRAM
POWER SUPPLY OUTPUT: (A) VARIABLE OUTPUT : 60V - 186V (DEPENDING UPON H.SYNC
FREQUENCY)
(B) CONSTANT OUTPUT : 7V, 20V, 29V, 54V, 80V
BEAD SET ABNORMAL VARIABLE OUTPUT
NG YES
OK NO
NG
OK
NG
OK
NG
OK
NG
NG
OK OK
OK
CHECK AC LINE
VOLT 120V OR 220V
CHECK F901,SW901
CHECK LINE
RECTIFIED &
SMOOTHED VOLT
CHECK MAIN POWER
CKT.
CHECK D901, D902,
D903, D904
CHECK POWER
SAVING CKT(OFF
MODE)
CHECK T901 O/P
CHECK 80V,55V,14.5V,
6.3V CIRCUIT
CHECK MCU H-SYNC
V-SYNC IC901
MAKE SURE THAT
THE VARIABLE
OUTPUT IS NOT SHORTED
CHECK IC401
PIN 4, 5, 6, B+
DEIVER
CHECK THE C934
VOLTAGE 55V
CHECK D919
CHECK Q911
Q911 FAILURE
CHECK Q912, Q914, Q915
CHECK Q901
IC901 FAILURE