ViewSonic Q51 series, E50C series Service Manual
1
SERVICE MANUAL
COLOR MONITOR
(Q51/E50C Series)
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: DEC.2004
2
TABLE OF CONTENTS
CONTENTS PAGE
1. SPECIFICATIONS ....................................................................................................…......... 3
2. PRECAUTION AND NOTICES ............................................…............................................. 4
2-1 SAFETY PRECAUTIONS ......................................................................…................... 4
2-2 PRODUCT SAFETY NOTICE .....................................................…….......................... 5
2-3 SERVICE NOTES ................................................................................……................. 6
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
4-4 EDID CONTENTS ....................................................……………….............................. 13
5. CIRCUIT DESCRIPTION ..............................................…………......................................... 13
6. TROUBLE SHOOTING CHART .....................................……………..................................... 16
6.1 NO RASTER, CRT RELATIVE CIRCUIT PROBLEMS ..........………………............. 16
6.2 ABNORMAL DISPLAY .................................................................……………………… 18
6.3 NO BLANKING ....................................……………………………………………………. 19
6.4 HOR./OSC/DEF/HV CIRCUIT FAULT ........................…………………………............. 19
6.5 ABNORMAL HORIZONTAL DEFLECTION ................…………………………………... 20
6.6 ABNORMAL VERTICAL SCANNING ...................................……………….................. 21
6.7 SIDE-PINCUSHION Distortions ....................................…………………………………. 21
6.8 POOR FOCUS ........................................................................………………………….. 21
6.9 POWER SUPPLY TROUBLE SHOOTING CHART.............................…………………. 22
7. MECHANICAL OF CABINET FRONT DIS-ASSEMBLY……………..................................... 23
8. BOM LIST .................................................................…………………................................ 26
9. BLOCK DIAGRAM............………………………………………………………………………… 41
9.1 BLOCK DIAGRAM (SMPS) ............…………………………………………………………
41
9.2 IC BLOCK DIAGRAMS ……………………………………………………………………… 42
10. PCB LAYOUT ................................................................……………….................................. 49
11. SCHAMATIC ……………………………………………………………………………………….. 51
3
1. SPECIFICATIONS FOR Q51/E50C SERIES COLOR MONITOR
CRT:
Type 15" (13.8” viewable diagonal area) CPT M36AES83X01 (L), LPD M36EDR320X304/6F01L;Dot Pitch 0.28 mm,
Shadow Mask, None Glare.
Viewable image Size: 35CM (13.8”) diagonal
Display Color: Unlimited Colors
External Controls:
Power On/Off, OSD key, Function knob: Contrast, Brightness, and Degauss. Horizontal Size, Horizontal Position,
Vertical Size, Vertical Position, Pincushion, Pincushion Balance, Trapezoid, Parallelogram, Tilt, Horizontal Moire,
Vertical Moire, ViewMatch color, ViewMeter, OSD Position, Languages, Memory Recall, Zoom.
Input Video Signal:
Timing Timing 15 Timing 16 Timing 17
Resolution
720*400 640*480 640*480
H (KHz)
31.327 31.469 37.5
V (Hz)
69.616 59.943 75.00
Timing Timing27 Timing 29
Timing37
Resolution
800*600 800*600 1024*768
H (KHz)
46.875 53.674 48.36
V (Hz)
75.00 85.061 60.00
Display Size:
Horizontal Display Size, Primary Preset 270 mm +/- 4 mm
Horizontal Display Size, Other Presets 270 mm +/- 4 mm
Vertical Display Size, Primary Preset 202 mm +/- 4 mm
Vertical Display Size, Other Presets 202 mm +/- 4 mm
Display Size Adjustment
All preset modes shall expand to
full screen size.
Scanning Frequencies:
Horizontal: 30KHz ~ 54KHz
Vertical: 50 Hz ~ 120 Hz
Factory Preset Timings: 6
User Timings: 19
4
Mis-convergence:
A Zone 0.25 mm
B Zone 0.30 mm
C Zone 0.35mm
Power Source:
Switching Mode Power Supply
AC 90-264 VAC 50/60 Hz
ENVIRONMENTAL
Operating Temperature 0°C to +40°C
Storage Temperature -40°C to +60°C
Operating Relative Humidity 5% to 95% Non-Condensing
Storage Relative Humidity 5% to 95% Non-Condensing
Operating Altitude -400 meters to +3000 meters
Storage Altitude -400 meters to +12,000 meters
Gross Weight: 13.0 kg
Dimensions Monitor:
Carton: 438mm (W) x 385 mm (H) x 455 mm (D)
Monitor: 360 mm (W) x 362 mm (H) x 384 mm (D)
External Connection:
15 Pin D-type Connector AC Power Cord
Regulations:
North America (M): UL/cUL, DHHS, TUV/S (Argentina) FCC-B, NOM, ICES-003, BSMI, PSB
International: CB, MPRII.
Power Saving Operation:
ON Mode < 70 Watts
OFF < 5 Watts
5
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. Symbol “
!
” means safety relative parts. The use of substitute replacement parts which do not have the same
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, VR701 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
59.0+
0.2Vdc at 640x480 60Hz and well seal it with A+B glue or equivalent, which you can not move away with
one screw driver.
7. 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.
6
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
25.5KV ± 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 20K 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.
7
3. OPERATING INSTRUCTIONS
This procedure gives you instructions for installing and using the Q51/E50C 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:
15 - Pin Color Display Signal Cable
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 Q51/E50C Series color display requires service, it must be returned with the power cord.
1
6
11 15
5
10
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
7. GND-G 15. SCL
8. GND-B
8
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
-MENU PCB - MAIN SW102
-UP
PCB - MAIN SW103
5. FUNCTION ADJ -DOWN PCB - MAIN SW104
-EXIT PCB - MAIN SW105
4. 3 ADJUSTMENT METHOD
14.5V, B + & HV voltage adjustment:
A. Chroma-2000 Signal generator or PC equivalent set mode2:, VGA 640X480 pattern 1.0.
B. Connect a DC Volt meter between TP901 (or the equivalent point) and ground, then adjust VR901 to be 14.2VDC.
C. Connect a DC Volt meter between TP902 (or the equivalent point) and ground, then adjust VR902 to be 85 VDC.
Factory preset Timings Adjustment:
A. Press Encoder control Key to show OSD window then press again to switch the functional controls.
B. Select to the "ZOOM" function, then press the button while does not release 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 to adjust its value
for the optimum picture.
White Balance adjustment(Bias ,Gain, ABL):
A. Bias (Raster luminance and cut off ) adjustment:
(a) Set mode 5 800×600 Fh: 53KHz 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) Change pattern to mode 5 Raster pattern (only Raster, no video), Brightness
set to maximum. Contrast
set to min., G-Bias 40, then adjust FBT screen VR. R-Bias . B-Bias to make Y= 3.5
±0.2cd/m², x= 265 ± 5, y= 290 ± 5.
(e) Raster cut off adjustment: adjustment the Brightness makes the Y=0.08±0.02cd/m², then save the adjustment
data to 9300 and 6500.
9
B. Gain (window white luminance) adjustment:
(a) Set mode 5 800×600 Fh: 53KHz window white pattern (100mm*100mm window).
(b) Brightness set to raster just cutoff and set the contrast to max.
(c) Adjust G-Gain
, B-Gain , R-Gain , to make color temperaturem Y=140±2 cd/m². x=283 ±
5, y=297 ± 5. then save to 9300
(d) Adjust G-Gain
, B-Gain , R-Gain , to make color temperaturem Y=140±2 cd/m². x=313 ±
5, y=329 ± 5. then save to 6500.
C. Recheck item A&B to make sure both of them in spec. Finally select OSD function to the 9300°K function, then
press to make the setting data saved in the memory.
D.ABL(Full white luminance) adjustment:
(a) Set mode 5 800×600 Fh: 53KHz full white pattern.
(b) Image Size: H: 270±3mm V: 202±3mm.
(c) Brightness set to raster just cut off and set the contrast to max.
(d) Adjust AB icon to the luminance at 103 ±1cd/m².
Focus Adjustment:
A. Set mode 5 800×600 Fh: 53KHz with character full page.
B. Adjust brightness to center and contrast to max.
C. Then adjust focus VR to a fine vertical and horizontal line.
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.
10
RELATIVE PLACEMENT OF TYPICAL COMPONENTS
Purity Magnets
Deflection Yoke
4-pole Convergence Magnets
6-pole Convergence Magnets
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.
OSD OPRATION
1
Displays Main Menu; also saves
Changes/exits Main Menu
4
Power Light
2
Scroll through menu
options and adjust the
displayed control
5
Power On/Off
3
Displays control screen for highlighted control (or pair of controls). Also, toggles between pairs of
controls on some control screens
1 2 3 4 5
11
Contrast adjusts the difference between the image background (black level) and the foreground (white
level)
Brightness adjusts the background black level of the screen image.
Zoom expands and contracts the entire screen image.
Horizontal Position moves the screen image left or right.
Horizontal Size adjusts width of the screen image.
Vertical Position moves the screen image up or down.
Vertical Size adjusts the height of the screen image.
User MENU 1
User MENU 2
12
Pincushion curves the vertical sides of the screen image.
Pin Balance curves the vertical edges of the screen image to the left or right.
Trapezoid adjusts the top and bottom of the screen image until they have equal length.
Parallel slants the vertical edges of the screen image until they are parallel.
Tilt rotates the entire screen image.
Degauss removes the build-up of magnetic fields that can cause irregular colors to appear around the edges of
screen images. There are two ways to degauss the display: automatically by turning the monitor on, or
manually by selecting the Degauss control from the menu.
With Degauss selected from the menu, press button [2] to degauss the monitor manually. Important: Do not
degauss repeatedly. Doing so can be harmful to the display. Wait at least 20 minutes (before selecting this
control again.
ViewMatch® Color provides several color options: several preset color temperatures and User Color which
allows you to adjust red (R), green (G), and blue (B). The factory setting for this product is 9300K (9300°
Kelvin).
9300K — Adds blue to the screen image for cooler white (used in most office settings with fluorescent
lighting).
6500K — Adds red to the screen image for warmer white and richer red.
5000K — Adds blue and green to the screen image for a darker color.
User Color — Individual adjustments for red, green, and blue.
Moire reduces interference patterns that appear as ripples, waves, or unwanted background color textures.
Interference patterns of this type are most noticeable when viewing images having closely spaced lines or
finely detailed patterns.
Language allows you to choose from among several languages for the menus and control screens: English,
French, German, Italian, and Spanish.
Memory Recall returns adjustments to the original factory settings if the display is operating in a factory preset
timing mode listed in this user guide.
Exception: This control does not affect changes made with the User Color control.
OSD Position allows you to move the on-screen display menus and control screens.
ViewMeter displays the frequencies (horizontal and vertical) coming from the graphics card of the computer.
13
4.4 EDID CONTENTS
0 1 2 3 4 5 6 7 8 9
________________________________________
0 | 00 FF FF FF FF FF FF 00 5A 63
10 | 1B 85 01 01 01 01 01 0E 01 03
20 | 1D 1C 15 B0 2A E0 58 9F 54 46
30 | 9B 24 10 48 4C FF F8 00 45 59
40 | 31 59 01 01 01 01 01 01 01 01
50 | 01 01 01 01 F9 15 20 F8 30 58
60 | 1F 20 20 40 13 00 0E CA 10 00
70 | 00 1E 00 00 00 FF 00 50 4C 36
80 | 30 34 30 31 30 30 30 30 31 0A
90 | 00 00 00 FD 00 32 78 1E 36 08
100 | 00 0A 20 20 20 20 20 20 00 00
110 | 00 FC 00 51 35 31 2D 39 0A 20
120 | 20 20 20 20 20 20 00 A4
5. CIRCUIT DESCRIPTION
5.1 MICRO CONTROLLER CIRCUIT
MICRO Controller
The IC101 contains a 8031 8-bit CPU core, 512 bytes of RAM, 32K bytes of ROM, 10 channel 8 bit PWM D/A
converters, 4 channel A/D converters, 216 bit timer/counters, internal H-sync and V-sync signals processor providing
mode detection, watch- dog timer preventing system from abnormal operation, and an I
2
C bus interface.
H/V sync signals processor
The functions of the sync processor include polarity detection, H-SYNC & V-SYNC signals counting, and
Programmable SYNC signals output, free running signal generator. Pin41/Pin42 are for the H-SYNC and V-SYNC input,
Pin34/Pin33 will output the same signal as input sync signal without delay, and the polarity is setting in the positive.
When no signal input, the Pin34 and Pin33 will output a free run signal for the monitor testing use.
On Screen Display Controller
The IC801 is designed for pre-amp and displaying 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.
Pin14/15/16 are used to output the B/G/R-bias.
Pin21/20/19 are used to output the B/G/R-gain.
Pin5/6/7 are used to input the R/G/B signal.
Pin11/12 are SDA/SCL.
Pin22 is used for the automatic Beam Limiter input.
Pin1, V Fly back, required for OSD synchronization and is also used for vertical blanking of the video outputs.
14
Pin2, V ref Bypass, provides filtering for the internal voltage.
Pin3, Vref, sets the internal bias current level for optimum performance.
5.2 DEFLECTION CIRCUIT
The deflection circuit is achieved by a high performance and efficient solution IC 401 (TDA4841) for this monitor. All
functions are controllable by IIC –bus.
The TDA4841 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 such as
TDA486*/TDA835*.
Horizontal Oscillator
The oscillator is of the relaxation type and requires a capacitor at pin29. A resistor from pin28 to ground determines the
minimum oscillator frequency. A resistor from pin28 to pin27 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 is connected to Pin26.
PLL2 Phase Detector
This phase detector is similar to the PLL1 detector and compares the line fly back pulse 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-fly back 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:
Pin6 (BDRV) is floating
Pin8 (HDRV) is floating
Pin13/12 (VOUT1 and VOUT2) are floating
Vertical Oscillator
The vertical free –running the capacitor at pin24 and the resistor at pin23 determine frequency. Usually the free-running
frequency should be lower than the minimum trigger frequency.
15
5.3 TRANSISTOR & DIODE CIRCUIT
LOCATION
CIRCUIT FUNCTION DESCRIPTION
D901 ~ D904 BRIDGE RECTIFIER FOR AC SOURCE
D918, D919 RECTIFIER FOR OUTPUT VOLTAGE
D921 RECTIFIER FOR OUTPUT VOLTAGE
D922 RECTIFIER FOR OUTPUT VOLTAGE
D923 RECTIFIER FOR OUTPUT VOLTAGE
D925 RECTIFIER FOR B+ OUTPUT VOLTAGE
D929 B+ FEED BACK RECTIFIER FROM F.B.T PULSE
Q907, Q908 USE FOR OFF-MODE TO CUT-OFF 6.3V SUPPLY VOLTAGE
Q909, Q910 USE FOR OF- MODE TO CUT-OFF 14.2V SUPPLY VOLTAGE
Q912, Q920 PUSH-PULL TOPOLOGY TO DRIVE Q911
Q913 DEGAUSSING SWITCHER TRANSISTOR
Q921 5V REGULATOR TRANSISTOR
Q401 TURN-ON AT POWER ON/OFF AND CHANGE MODE TO PROTECT HOR.BLOCK
Q460 HOR. DRIVER TRANSISTOR
Q408 AS A SWITCHER FOR HORIZONTAL S CORRECTION CKT
Q410 HORIZONTAL S CORRECTION CONTROL MOSFET
Q404, Q405 AS DIFFERENTIAL AMP. TO DRIVE Q406
Q406 DARLINGTON TRANSISTOR FOR H-SIZE CONTROL
Q705 G1 CONTROL CKT
16
6. TROUBLE SHOOTING CHART
6.1 NO RASTER, CRT RELATIVE CIRCUIT PROBLEMS
N
G
CHECK THE HIGE VOLTAGE
OF CRT ABOUT 24.5~25.5V
CHECK LOWER POWER CIRCUIT
H-SYNC,V-SYNC SIGNAL
Q909,Q910
CHECK MAIN PCB POWER
SUPPLY 76V,14.2V
CHECK THE VOLTAGE OF CRT
HEATER ABOUT 6.3V
CHECK FAILSAFE CKT IC401 PIN2
RELATIVE CKT.
REFER ITEM S.M.P.S
O
K
N
G
OK
CHECK CRT’S HEATER RELATIVE
CIRCUIT D923
CHECK SCREEN VOLTAGE
ABOUT 500V TO 700V
BRIGHTNESS SET TO MAX
CHECK VOLTAGE OF THE CRT
CATHODE ABOUT 40Vpp
CHECK FBT
LESS THAN 300V
CHECK G1 CIRCUIT Q705
RELATIVE CKT
REFER ITEM 6-2 “ABNORMAL
DISPLAY”
NG NG N
G
OK
OK
OK
OK
17
2.ABNORMAL VIDEO LEVEL ON SCREEN
3.ABNORMAL DDC (PLUG & PLAY)
NG
OK
CHECK IC101 PIN5 VOLTAGE
ABOUT:5V
CHECK SIGNAL CABLE OR H802
PIN4/5
CHECK Q921 GOOD OR FAIL
CHECK THE VOLTAGE OF IC801
PIN10/18 ABOUT 5V
CHECK 5V RELATIVE
CIRCUIT
CHECK THE IC801 PIN23
RELATIVE CIRCUIT
CHECK IC801 PIN5/PIN6/PIN7
RELATIVE CIRCUIT
CHECK THE VIDEO OUTPUT OF
IC801 PIN19/20/21 ABOUT 3Vpp
AND PIN14/15/16 ABOUT 2V
CHECK IC801 PIN23 CLAMP
PULSE
CHECK THE SIGNAL INPUT OF
R.G.B
ABOUT 0.7V
pp
CHECK SIGNAL CABLE OR
INTERFACE CARD.
R.G.B APPROACH STANDARD
OK
N
G
OK
N
G
OK
N
G
O
K
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