Tatung Vibrant VM99S User manual

19-inch Color Monitor
VM99S
Service Manual

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VM99S
Table of Contents
1. Precautions .................................................................................................................2
2. Product Specifications ..............................................................................................5
3Control Location and Functions .............................................................................10
4. Operation Theory.....................................................................................................11
5. Alignments and Adjustments...................................................................................16
6. Troubleshooting........................................................................................................21
7. Recommended Spare Parts List..............................................................................27
8. Block Diagram..........................................................................................................29
9. Exploded Diagrams ........................................................................................ Inserted
10. PCB Diagrams ................................................................................................ Inserted
11. Schematic Diagrams ...................................................................................... Inserted

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1Precautions
Follow these safety and servicing precautions to prevent damage and to protect against potential hazards
such as electrical shock and X-rays.
1-1 Safety Precautions
1-1-1 Warnings
1. For safety purpose, do not attempt to modify
the circuit board, and always disconnect the AC
power before performing servicing on the
monitor.
2. Operation of the monitor outside its cabinet or
with the cover removed involves the risk of
shock hazard. Repair work on the monitor
should only be attempted by service personnel
who are thoroughly familiar with all necessary
safety precautions and procedures for working
on high voltage equipment.
3. Do not lift the CRT by the neck. After
completely discharging the high voltage anode,
handle the CRT only when wearing shatterproof
goggles. Try to keep the CRT away from the
body during handling.
4. High voltage should always be kept at the rated
value, no higher. Only when high voltage is
excessive are X-rays capable of penetrating the
shell of the CRT. Operation at high voltages
may also cause failure of the CRT or high
voltage circuitry.
5. The CRT is especially constructed to limit X-
ray emission to 0.5mR/HR at 300 microamperes
anode current. To ensure continued X-ray
protection, replace the CRT with only the same
or equivalent type as the original, and adjust the
anode’s voltage to the designated maximum
rating, never to exceed.
1-1-2 Safety Checks
Before returning the monitor to the user, perform
the following safety checks:
1. Inspect to make certain that each lead dress is
not pinched or that hardware is not lodged
between the chassis and other metal parts in
the monitor.
2. Inspect all protective devices such as
nonmetallic control knobs, insulating materials,
cabinet backs, adjustment and compartment
covers or shields, isolation resistor-capacitor
networks, mechanical insulators, etc.
3. AC Leakage Current Check
Always perform the AC Leakage Current
Check on the exposed metal parts, including
metal cabinets, screwheads and control shafts,
as follows:
a) Plug the AC line cord directly into a rated
AC outlet. Do not use an isolation
transformer during the check.
b) Use an AC voltmeter with at least 5000
ohms per volt sensitivity as follows:
Connect a 1500 ohms, 10 watt resistor
paralleled by a 0.15uF AC capacitor in series
with all exposed metal cabinet parts and a
known earth ground, such as electrical
conduct or electrical ground connected to
earth ground, as shown in the Figure 1-1.
Measure the AC voltage across the
combination of resistor and capacitor.
c) Reverse the AC plug at the AC outlet and
repeat the steps for AC voltage
measurements for each exposed metal part.
d) Voltage reading must not exceed 0.3 volts
RMS,equivalentto0.2 milliampereAC. Any
value exceeding this limit will constitute a
potential shock hazard and must be
corrected immediately.
Figure 1-1. Set Up For AC Leakage Current Check
To known
earth ground
1500 ohm 10 watt
0.15ufd
To exposed metal
cabinet part

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VM99S
1-1-3 Product Safety Notices
Many electrical and mechanical parts in this chassis have special safety-related characteristics which are
often not evident from visual inspection, the protection afforded by them may not be obtained by replacing
them with components rated for higher voltage, wattage, etc. Before replacing any of these components,
consult the Recommended Spare Parts List given at the end of this manual. Any of the replacements that do
not provide the same safety characteristics may result in shock, fire, X-ray emission or other hazards.
1-2 Servicing Precautions
Warning: An electrolytic capacitor installed with the wrong polarity might explode.
Caution: Before performing servicing covered by this service manual, read and follow the Safety Precautions
section of this manual.
Note: If there are any unforeseen conflictions between the following servicing precautions and any of
the safety precautions, always follow the safety precautions.
1. Follow closely the servicing precautions printed on the monitor cabinet and chassis.
2. Always unplug the AC power cord from the AC power source before removing or installing any component
or assembly, disconnecting PCB plugs or connectors and connecting a test component in parallel with a
capacitor.
3. When replacing parts or circuit boards, clamp the lead wires around the component before soldering.
4. When replacing a high wattage resistor (>0.5W metal oxide film resistor) in the circuit board, keep the
resistor about 1 cm (1/2 inch) away from the circuit board.
5. Keep wires away from the high voltage or high temperature components.
6. Keep wires in their original positions so as to minimize interference.
7. Always connect a test instrument’s ground lead to the instrument chassis ground before connecting the
positive lead; always remove the instrument’s ground lead last.
After putting the rear cover back on and making sure the monitor is working properly, the Hi-
Pot & Ground Continuity tests MUST BE performed before the monitor is returned to user.
1-3 Hi-Pot Test
1. Test Equipment
Puncturetest modelPM5530ADT orKIKUSUTOS-8750 voltagetesteror equivalentapprovedequipment.
Note : The test equipment must be calibrated in regular period.
2. Test Setup
a) Apply voltage : DC 2100 VDC
b) Test duration : 3 seconds
c) Cutoff current should be set to 3 mA
3. Test Procedure
a) Unplug power cord from AC source.
b) Put the power switch of the monitor in the “ON” position.
c) Leave signal cable un-connected.

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VM99S
d) Plug monitor power cord to the Hi Pot tester terminals.
e) Turn on tester and watch the indicator or beeper.
f) If the indicator lamp lights, or beeper beeps, the test fails.
1-4 Ground Continuity Test
1. Test Equipment
AC low ohm tester TOS-6100 or equivalent approved equipment.
Note : The test equipment must be calibrated in regular period.
2. Test Setup
a) Test duration : 3 seconds
b) Set current limit at 25 A
c) The grounding resistance must be less than 0.1 ohm.
3. Test Procedure
a) Plug the monitor power cord to the tester terminals.
b) Make sure all connections are well-contacted.
c) Turn on monitor power and tester power.
d) Press “Test” button.
e) If green light shows up, means test OK.
If red light shows up, means test fails.
f) If the Tester has a digital display, the resistance value must not exceed 0.1 ohm.
Note : Be sure not to touch the metal portion of the signal cable head during testing.

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VM99S
2Product Specifications
2-1 Specifications
Note: Above specifications are subject to change without prior notice.
Picture Tube 19-inch, (18-inch visual image area) sloted mask, 90 degrees deflection, dot type black matrix, medium short persistence
phosphor, dark tint, non-glare/ anti-static screen,
0.26 mm dot pitch
Scanning Frequency VGA, Super VGA, 1024x768@75/85 Hz, 1280x1024@85 Hz
Maximum Resolution 1600 dots (H) x 1200 lines (V) @75Hz refresh rate
Display Area 350 mm (H) x 262 mm (V) typical
Display Characters 80 char. x 60 rows on a 10 x 10 matrix
Display Colors Analog
Input Unlimited Colors
Synchronizatin Signals Separate Sync: horizontal/vertical, TTL, positive or negative
Synchronization
Frequencies Horizontal : 30 to 96 kHz Vertical : 50 to 160 Hz
Signal Connectors 15-pin, D-shell connector
Video Signals Analog : 0.7 Vp-p, RGB positive
Power Input 120 Watts (maximum) AC rated voltage, 100VAC to 240VAC,
200VAC to 240VAC for PNST/PNSL models
Misconvergence Center Area : <0.3 mm; Corner Area : <0.4mm
User Controls
Power On/Off, Contrast, Brightness, Horizontal Size,
Horizontal Position, Vertical Size, Vertical Position,
Pincushion, Trapezoid, Pin Balance, Parallelogram, Rotation,
Color temperature, Language, Display Frequency, Degauss,
Recall, H. Moire, V. Moire
Service Controls PWB-1596/1598 : power voltage adjust (VR801)
focus 1 , focus 2
Preset Modes 10 (see Table 2-2. Timing Chart)
Environmental
Considerations Operation temperature : 5oC to 35oC ambient Operation Humidity : 20% to 80% ambient
Storage temperature : -40oC to 65oC ambient
Storage Humidity : 5% to 95% (non-condensing)
Altitude : up to3000m above sea level

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2-2 Signal Cable Pin Connections
Table 2-1. Signal Cable Pin Assignment
Pin Signal Pin Signal
1Red video 9+5V
2Green video 10 Digital Ground
3Blue video 11 Ground
4Ground 12 SDA
5* Ground 13 H-Sync
6Red ground 14 V-Sync/VCL
7Green ground 15 SCL
8Blue ground
Note: * This pin is used for selftest detection. Connect this pin to ground at the PC end.

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VM99S
2-3 Timing Chart
This section describes the timings that the computer industry recognizes as standard for computer-generated
video signals.
Table 2-2. Timing Chart
Seperate Sync
Horizontal
Video
C
D
E
Sync
A
B
F
Vertical
Video
I
J
Sync
G
H
L
K
H.Parameters:
A: Period B: Blanking Time
C: Sync Width D:Back Porch
E: Active Time F: Front Porch
V.Parameters:
G: Period H:Blanking Time
I: Sync Width J: Back Porch
K: Active Time L: Front Porch
Mode 1 2 3 4 5 6 7 8 9 10
H. Dots 640 720 640 832 800 1152 1024 1600 1280 1600
V. Dots 480 400 480 624 600 870 768 1200 1024 1200
H-freq (kHz) 31.47 37.927 43.27 49.725 53.67 68.681 68.67 75 91.146 93.75
Sync Polarity - - - - +-+-+ +
A period us 31.78 26.366 23.11 20.11 18.631 14.561 14.561 13.333 10.971 10.667
B Blanking us 6.356 6.085 5.33 5.586 4.409 3.04 3.725 3.457 2.844 2.765
C Sync us 3.81 2.028 1.556 1.117 1.138 1.28 1.016 1.185 1.016 0.948
D B.P. us 1.907 3.042 2.22 3.91 2.702 1.44 2.201 1.877 1.422 1.501
E Active us 25.42 20.282 17.78 14.524 14.222 11.52 10.836 9.877 8.127 7.901
F F.P. us 0.636 1.014 1.556 0.559 0.569 0.32 0.508 0.395 0.406 0.316
V-freq (Hz) 59.94 85 85 74.55 85 75.062 84.99 60 85 75
Sync Polarity -+- - +-+-+ +
G Period ms 16.68 11.759 11.76 13.414 11.756 13.322 11.765 16.667 11.761 13.333
H Blanking ms 1.43 1.213 0.67 0.864 0.578 0.656 0.582 0.667 0.527 0.533
I Sync ms 0.064 0.079 0.069 0.06 0.056 0.044 0.044 0.04 0.033 0.032
J B.P. us 1.02 1.107 0.578 0.764 0.503 0.568 0.524 0.613 0.483 0.491
K Active us 15.25 10.546 11.09 12.549 11.179 12.667 11.183 16 11.235 12.8
L F.P. us 0.35 0.026 0.023 0.04 0.019 0.044 0.015 0.013 0.011 0.011

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VM99S
2-4 Power Saving Function
Note: The monitor will be driven into “Power Saving” mode by the control signal from the display
controller, as indicated by the amber-color power LED.
Table 2-3. Power Saving Function
State Power
Consumption LED
Light
ON <120 watts Green
Active
OFF <3 watts Amber
The power saving states will be kept until a control signal has been detected or the keyboard or mouse is activated.
The recovery time from Active OFF state back to ON state is around 10 seconds.
2-5 TCO Version (Optional)
The monitor meets the TCO 99, NUTEK energy saving, electric and magnetic field requirements.
2-5-1 TCO 99 Version (Optional)
The emission from magnetic and electric field must comply with the limits specified by the Swedish Board
for Measurement and Testing, commonly known as MPR 1990 recommendations. These limits are
summarized in the Table 2-4.
Table 2-4. TCO 99 Requirements
VLF/TCO ELF/TCO
Magnetic Field 25 nT 200 nT
Electric Field 1 V/m 10 V/m
Frequency Range 2~400 kHz 5~2000 Hz
Value RMS RMS
Distance 30 cm 30 cm
Electrostatic
Potential +/- 500 V +/- 500 V

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VM99S
ThemonitorisdesignedwithselectedCRTandcarefullyroutedwiresaround CRT,makesureexactlythe
samerouting schemeisusedwhendoing CRTreplacement.
TheTCO99 schemeisforinternationalandenvironmentallabellingofpersonalcomputers.Thelabelling
schemewasdevelopedasajointeffortby theTCO(TheSwedishConfederation ofProfessionalEmploy
ees),Naturskyddsforeningen(TheSwedishSocietyforNatureConservation)andNUTEK(TheNational
BoardforIndustryandTechnicalDevelopmentinSweden).
1)`Scope
TCO99toucheson ergonomicqualities,emissions(electricalandmagneticfields),energyefficiencyand
ecology(withdemandsforenvironmentaladaptationforboththeproductand theproductionprocessesat
themanufacturingplant).
2)EnvironmentalRequirements
Themonitorabidesbytheenvironmentaldemandsconcerning restrictionson thepresence and useof
heavy metals,brominatedand chlorinatedflameretardants,CFCs(freons),and chlorinatedsolvents,
amongotherthings.Themonitorisalsorecyclable.
3)EnergyRequirements
Themonitoralsofollowstheenergyrequirementsthat,afteracertainperiod ofinactivity,themonitor
shallreduce itspowerconsumption toalowerlevelinoneormorestages.
4)Others
Themonitormeetsthestrictenvironmentaldemandsforthereduction ofelectricand magneticfields,
physicalandvisualergonomicsandgood usability.
Table2-5.TCO99VisualErgonomics
Feature Standard Description
Linearity 1% or less Difference in length of columns or rows compared to the
corresponding lengths through the center of the monitor.
Display Luminance 100 cd/m2 (at least)
Luminance
Uniformity 1.5:1 or less The ratio is between the max to min luminance within the whole active area.
Color temperature
variation delta u'v' <0.01
Reclections from
casing >20% / <30glass The reflection ration is on cabinet & table.

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VM99S
3Control Location and Functions
3-1 Front Panel
3-2 Front Panel Keys Functions
1. Function Key: Display the main menu, and exit the adjustment screen and save adjustments.
2. Decrease Key: Scroll across main menu, highlighting control to be adjusted. Decrease value of selected
control. Toggle between Contrast and Brightness adjustment screens.
3. Increase Key: Scroll across main menu, highlighting control to be adjusted. Increase value of selected
control. Toggle between Contrast and Brightness adjustment screens.
4. Select Key: Press once to display adjustment screen. Press again, for some controls, to toggle between
controls shown in pairs on main menu.
5. Power LED: Display different modes (ON, OFF) of the monitor by showing different color for each
mode.
6. Power ON/OFF: To turn the monitor ON and OFF.
3-3 Adjustment Procedure
1. Press (6) key to turn on the monitor.
2. At normal condition, press (1)on the front panel to activate the on-screen manager (OSM) menu.
3. To select a user control, press (2) or (3) key repeatedly until the control is highlighted.
4. To adjust the value for a particular control, press (4), then press the (2) or (3) key to obtain the desired
value. There are a few parameters that do not require any adjustment, like Manual Degauss, Memory
Recall.
5. Some controls are grouped in pairs on the main menu. Press (4) key to toggle between them.
6. To save your adjustments and exit screen, press (1) key. The menu will automatically clear out from the
screen if no keys are pressed within 30 seconds.
Note: To enter the “Internal Adjustment” mode, press (1) & (4) keys simultaneously then press (6).
(1) Function Key
(2) Decrease Key
(3) Increase Key
(4) Select Key
(5) Power LED
(6) Power ON/OFF
(1) (2) (3) (4) (5) (6)
1
2

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4Operation Theory
This is a fully digital controlled multi-sync color monitor that is compliant with DDC1/2B Plug and Play
VESA standard and offers the following main features.
4-1 Main Features
1. Simplified design with minimum components.
2. The NOVATEK NT68P65AU processor-- that has I2C bus controlled geometric correction, contrast and
brightness-- offers the functions for: (a) Contrast, (b) Brightness, (c) H-size, (d) H-position, (e) V-size, (f)
V-position, (g) Pincushion, and (h) Trapezoid, (i) Pin Balance, (j) Parallelogram.
In addition, it also offers more functions as: (a) Sync. processor, I/P and O/P, (b) Mute, (c) Power saving
off, (d) Power saving override, (e) DDC2B, (f) I2C Bus for auto-alignment through signal cable (g) CS
switching for linearity and size compensation, (h) High voleage adjustment, (i) G2 voltage adjustment.
3. Stores up to 10 factory preset modes and offers 6 user modes. There are 18 function icons in OSD. They
are controlled by 12keys on the front panel.
4. Powerful PHILIPS TDA4841 and TDA4863 present the following useful functions: (a) Pincushion, (b)
Trapezoid, (c) V-Position, (d) V-Size, (e) Vertical’s “C” and “S” correction -- factory adjust, (f)
Pincushion’s V. position correction, (g) Corner correction -- factory adjust, (h) Pincushion unbalance
correction -- factory adjust, (i) Parallelogram distortion -- factory adjust, (j) Moire cancellation, (k) X-ray
protection, and (l) Full horizontal and vertical auto sync capability.
5. Software controlled auto shut off function activated if fH < = 29 kHz and fH > = 96 kHz.
6. Full range AC input and simplified line filter design.
4-2 Microcontrol Section
1. This monitor uses NOVATEK NT68P65AU CPU. It contains a 8-bit CPU core, 256 bytes of RAM used
as working RAM and stack area, 24k bytes of OTP ROM, 14-channel 8 bit PWM D/A converter, 2-
channel A/D converters for key detection saving I/O pins, internal H. sync and V. sync signals processor
providing mode detection, and an I2C bus interface. When H/V sync through D-Sub signal cable enter pin
41 and pin 42, the CPU performs frequency / polarity detection and calculate and send to H/V sync OUT.
Then CPU reads the data from I703 and transfer to device 4841 and some DAC in CPU, above operation
takes about 500 ms.
2. There allows 10 factory preset modes and 6 user modes. There are 8 functions, Contrast, Brightness, H.
Size, H. Position, V. Size, V. Position, Pincushion, and Trapezoid, all controlled by OSD icon which can be
adjusted by user.
3. The pin 25 and pin 26 are used for ATE function. When CPU receives C6 as slave address, it will operate
in ATE mode which is used for auto-alignment. After alignment the data will be stored in I703.
4. The user control parameters are selected by OSD icons, through 12keys, they are detected by
sensing the voltage through R710, R759, R713, R714, R709, R711, R760 to pin 16 and 17 of I701.
4-3 Deflection Section
1. I2C -- autosync deflection controller is TDA4841.
2. The TDA4841 is a high performance and efficient solution for autosync monitors. All functions are
controllable by I2C bus. SDA and SCL signals coming from microprocessor feed to pin 19 and pin 18 to
control all functions.

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VM99S
4-3-1 Horizontal Section
1. The oscillator is driven by the currents in R472 and R468. The minimum oscillator frequency is determined
by R472 and the maximum frequency is determined by R468.
2. Horizontal sync goes into pin 15 through R494. And horizontal flyback pulse goes into pin 1 through R479
and bypass filter C445 from Emitter of Q407 and C412, C433, C411, R419, C456, R421, D413 for AFC
loop.
3. Horizontal driver (pin8) output to Q401 via C401, Q401 switching to drive T401 provide IB1/IB2 current
then turn on/off Q402 and switching the yoke current.
4-3-2 Vertical Section
1. Vertical sync goes into pin 14 through R493.
2. The free running frequency is determined by R470 and C442.
4-3-3 Vertical O/P section
1. The differential output currents from pin 13 of Vout1 and pin 12 of Vout2 can be directly coupled to the
vertical deflection booster pin 3 and pin 2 of TDA4863.
2. The TDA4863 has two output stages which are current driven in opposite phase and operate in combination
with the deflection coil in a half bridge configuration.
3. This IC is powered by three sets of positive voltage. (+13V at pin1, 37V at pin 8, -13V at pin 6)
4-3-4 E-W/Trapezoid and H. Width Controls
1. The scan current is determined by B+ (the voltage of C413) that is obtained from step down circuit
output. Step down circuit include Q404, T402, D407.
2. I401 TDA4841 pin 6 (B DRV) will drive the step down circuit to change H. width.
3. EW DRV (pin11) provides a complete EW drive waveform including parabola, corner and trapezoid
correction and feed to BIN (pin 5 of I401) to get a good control for pincushion / trapezoid / corner.
4. The top and bottom corner correction can be adjusted seperately.
4-3-5 X-Ray Protection
1. To avoid X-ray hazard, a DC voltage generated at pin 6 of FBT and rectified by D107, C111 and divided
by R476, R477 and R478 come into pin 2 of TDA4841.
2. If this voltage is higher than 6.39 V, then TDA4841 will be activated to float HUNLOCK (pin17), H.
DRV( pin 8), B DRV (pin 6), VOUT1 (pin 12), VOUT2 (pin13). After that all deflection circuit stop
working.
4-3-6 Blanking and Brightness
1. The vertical blanking signal comes from I401 pin 16 and vertical sync. These two pulses combine into
Q542 and Q541. This signal feets into T501 pin 24.
2. In protection mode or out of range or mode change mute signal will turn high and turn on Q107.
G2 voltage will drop from 600V to 250V.
3. The brightness is control by I2C bus. The output pins are I501 pin 14, pin 15, pin16.

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VM99S
4-3-7 Contrast Section
1. Contrast is controlled by I701 through I2C bus to I501 (LM1267) directly.
2. Beam current is detected through T101 (FBT) pin 7, D106, C109, Q102, R108, R121, R122 to control
I501 pin 22 voltage. When I501 pin 22 voltage drops below 5V, the ABL function will happen.
4-3-8 Dynamic focus circuitry
The dynamic focus is applied to improve the corner focus performance, it includes horizontal and vertical
dynamic focus.
1. Vertical dynamic comes from I401 pin 32 and is amplified through C105, Q101, C137, and feed to FBT
dynamic focus pins R133, R132, Q101.
2. This amplifier need 200V voltage supply, it comes from FBT pin 8 and rectified through L102, D101, and
C102.
4-4 Power Supply Section
4-4-1 AC Rectifier
The circuit can accept 90 V to 264 V AC input through D801 bridge diodes and C808 filtering to get DC 126
V~364 V for power conversion in T802.
4-4-2 Line Filter
It consists of C801, C802, C803, C816, C820, C823, T801, T804 and meets EMI regulation.
4-4-3 Power LED Status
1. The LED has 3 leads with common cathode to emit green and amber color light for different power
saving states.
2. Normal : Green light
3. Off Mode : Amber light
4-4-4 Auto Degaussing
When S801 turns on, pin 27 of I701 will send a signal to Q802 and turns on RL801 for degaussing. After 4
seconds, it will turn off RL801 automatically.
4-4-5 PWM Control
1. Start Up
The I801 (KC3843B) gets power from R846, Q821, R849, R848, D826, D828, D822 and pin 7 voltage
reaches 8 V for starting up. The I801 starts oscillation at 22 kHz, sawtooth on pin 4 and pin 6 output to
drive Q803/T802. Once Q803 switching on, D806, C804 set up an 15 V to keep I801 working through
D821 auxiliary voltage.
2. Regulation
The DC O/P voltage is proportional to the auxiliary voltage, so I801 pin 2 senses the feedback voltage
from the divider R802, R823, VR801 and R820 to compare with the built-in 2.5 volts reference voltage for
error amplifier operation. Finally pin 6 can modulate the different duty cycle by VR801 setting to achieve
regulation purpose.

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VM99S
4-4-6Synchronization
1.NormalMode
ThesyncpulsefromFBT(31kHz~95 kHz)viaR812,R831,C815,R826,D824,C814and R816 topin4
ofI801tokeepI801synchronizedwithhorizontalsyncinputfrequency.
2.PowerSavingModes:Off mode
Becausethereisno pulsefromFBT,sothefree-run frequencyisdecidedby R817and C814 and the
SMPSworksat22 kHz.
3.Override
Thehorizontalfreerunfrequencyisabout62.5kHzunderoverridecondition,SMPS issynchronizedto
thisfrequency.
4-4-7O.V.P.
IftheauxiliaryvoltageishigherthanzenervoltageZD807 (20volts)andmakespin3ofI801higherthan
1V,pin6dutycycleislimitedtohavetheOVPactivated.
4-4-8O.P.P.
TheexcesscurrentofT802 throughR813,R814,R834,C813,R865 andR864 candevelop enoughvoltage
onpin3thenlimitthepowerdeliveredbecausethepin6dutycycleislimitedtoo.
4-4-9HighVoltageGenerationwithF.B.T.
1.TheH.Vgeneration circuit combinesT101 F.B.T.withI101TL494/KA7500 PWMcontrolcircuit.
2.WhenI101,Vcc(pin12)reachesat12V,pin5,6getsafreerun sawtoothwaveformabout25KHz,and
approximately5.7Vp-p,whenvoltaheatpin15 ishigherthanpin16 (5Vreference)thenreleasepin3to
becontrolledbypin1feedbacksignaland comparewithpin5tooutputPWM.
3.HFLB1isusedtotriggerpin5viaQ112,tosynchronizethedeflectioncircuit.
4.PWMoutputwill driveQ116&T101togereratehighvoltage(26KV),T101 pin11,15becomesDC/AC
feedback,withthevoltagelinktoI101non-invertinginputpin1tostabilize H.V(26KV)andI101 canbe
adjustedtocontrolH.Vvalue.
5.WhenX.R.Poccur,thehunlockwillkeephightopull downI101pin2andshutdownPWMoutput.
4-5VideoAmplifier Section
1.RGBsignalinputsareterminatedby R501,R531andR561 thenpassthrough thecoupling capacitors
C501,C531and C561toIC501LM1267preamplifier.
2.TheamplifierRGBsignals(0~4Vpp)areadjustedbyI2CbusfromI501,pin23isforclamppulsewhich
comesfrompin16 ofTDA4841.
3.ThevideooutputstagesareamplifiedbyI901(LM2465).TheRGBcathodescutoffareadjustedbyI2C
buscontrolbyinternalicon.
4.Underoverridecondition,“CHECKSIGNAL”willshowup on thescreen.
4-6OSD(OnScreenDisplay)Circuit

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VM99S
1. The I502 NT6827-00002 is OSD IC. The OSD signals are worked by positive vertical pulse from I701 pin
32 that goes through R554 to I502 pin 10, and positive horizontal pulse from HFLB1 through R527 to I502
pin 5. CPU I701 pin 27, 28 (I2C bus) transfers information to I502 pin 7, 8.
2. The OSD R. G. B signals and blanking signal are terminated at I502 pin 15, 14, 13, and 12 feed into I501
pin 1,2,3, and 4, then the OSD picture appears.

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VM99S
5Alignments and Adjustments
This section of the service manual explains how to make permanent adjustments to the monitor settings.
5-1 General Adjustments
5-1-1 Adjustment Conditions
a) Power Supply
Apply AC 115 V or 220 V
b) Warm-up Time
The monitor must be powered on for 15 minutes before starting any alignment, but requires 30 minutes of
warm-up time for convergence adjustment.
c) Signal Input
1. Video: RGB Analog, 0.7 Vp-p, positive
2. Synchronization: Horizontal and vertical TTL signal, separate, positive or negative
3. All adjustments should be made using a signal of FH = 91 kHz, FV = 85 Hz, unless otherwise defined.
5-1-2 Equipment Required
The following equipments are necessary for adjustment procedures:
1. Volt-ohm-A meter (Sanwa FD-750C or equivalent)
2. 30 kV high voltage probe (HP34111A)
3. Oscilloscope (TEK2235 or equivalent)
4. Minolta Color Analyzer II
5. Signal generator (COMPAQ PC with proper display cards or Chroma 2250//2225)
6. Screwdriver
5-1-3 Switching Power Supply and Regulator Adjustment
a. The regulated B+ control has been preset in the factory and needs no adjustment. However, if any repair
is made on the power supply section, the following readjustment procedures are recommended:
1. Allow the monitor to warm-up for about 15 minutes.
2. Apply XGA (1280 x 1024 @ 91 kHz/85 Hz) signal to the monitor.
3. Connect a DC voltage meter to TP001 end, and adjust VR801 for 10.7 +0.1 V DC
4. If a fuse is broken during adjustment, remember to replace it with the exact same type of fuse.
b. If necessary, follow the following procedures to enter the factory mode.
1. Press both 1key and 2key simultaneously then power On.
2. After turn the power off, monitor will go back to normal mode.

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VM99S
5-2 Alignment Procedures
5-2-1 High Voltage Adjustment
CONDITION
Display image : Crosshatch pattern
5-2-2 Screen and White Balance Adjustment
CONDITION
Press 1and 2buttons simultaneously when switching the power “On”.
Display image : No video
PROCEDURE
1Raster color setting
1-a Adjust HV icon to set high voltage = 26KV.
1-b Adjust G2 icon to set G2 at 600 ± 5V
1-c Set Brightness icon maximum to 40%
1-d Select OSD icon to R.G.B. cutoff
1-e Set G gun cutoff to 0.5 ± 0.15 FL
1-f Adjust R/B cutoff to get x=283 ± 5, y=297 ± 5, Y=0.6 ± 0.2 FL
1-g Set Brightness to cutoff , get Y=0.01 ~ 0.03 FL
1-h Set Brightness to minimum.
CONDITION
Display image : 50 mm x 50 mm white block pattern
PROCEDURE
265000K color temperature setting
2-a Set Brightness to cutoff and Contrast to 75 Value
2-b Move cursor on OSD to choose color temperature icon.
2-c Press 2key to G gain then adjust G gain = 70 value, then adjust B, R to x=313±5, y=329±5.
2-d Check x=313±5, y=329±5.
393000K color temperature setting
3-a Move cursor on OSD to choose color temperature icon.
3-b. Press 2key to G gain then adjust G gain = 75 value, then adjust B, R to x=283±5, y=297±5.
3-c Adjust Contrast max. to set Y=38±2FL
3-d Check x=283±5, y=297±5.
3-e Adjust Contrast min. to set Y=1.0FL.
4Full white ABL setting

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VM99S
CONDITION
Display image : full white pattern
4-a Set Brightness to cutoff and Contrast to maximum.
4-b Move cursor to choose ABL inside contrast icon.
4-c Adjust ABL to set Y=32±1FL
4-d Repeat all the procedures in 5-2-2 section until the best white balance is obtained.
5-2-3 Focus Adjustment
CONDITION
Display image : “e” character pattern
PROCEDURE
1. Set Brightness to cutoff and Contrast to maximum.
2. Adjust top VR at T101 (static focus VR) to make vertical line clear.
3. Adjust center VR at T101 (dynamic focus VR) to make horizontal line clear.
4. Repeat above procedures to get best focus.
5-2-4 Dynamic focus Adjustments
1. Horizontal dynamic focus set Hf=370V ±10 V in phase (compare with Vcp signal).
2. Vertical dynamic focus set Vf=145V ±10V in phase.
5-2-5 Static Convergence Adjustments
Static convergence involves alignment of the red, blue and green lines in the center area of the display.
Note : The monitor requires 30 minutes warm-up time for convergence adjustment.
CONDITION

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VM99S
Display image : Crosshatch pattern
Warm-up Time : 30 minutes
PROCEDURE
1. Set Brightness and Contrast to display a well-defined pattern.
2. Ensure the convergence magnet rings are correctly positioned on the CRT.
Figure 4-1. Convergence Magnets on the CRT
+
87 65 4 3 2
10
1
11
CRT
FRONT
P
9
1) Setup Bolt 2) Bow Magnet 3) Band 4) 4-Pole Magnet
5) Spacer 7) Spacer
9) Holder 6) 6-Pole Magnet 8) 2-Pole Magnet 11) Tabs10) Band
3. Rotate the individual rings of 4-pole convergence magnets by changing the spacing between the 2 tabs to
converge the vertical red and blue lines at the center of the screen.
4. Rotate the pair of rings of 4-pole convergence magnets by maintaining spacing between the 2 tabs to
converge the horizontal red and blue lines at the center of the screen.
5. Rotate the individual rings of 6-pole convergence magnets by changing the spacing between the 2 tabs to
converge the vertical red, blue and green lines.
6. Rotate the pair of rings of 6-pole convergence magnets by maintaining spacing between the 2 tabs to
converge the horizontal red, blue and green lines.
7. Repeat the steps from 3~6 until the best convergence is obtained.
Figure 4-2. 4-pole and 6-pole Magnets Movement
Note : The 4-pole magnets and the 6-pole magnets interact, making dot movement complex.
Blue Red
Blue
Red
Red/
Blue Green
Red/
Blue
Green
4-pole magnets
movement
6-pole magnets
movement