LITE-ON B1996ns Service Manual

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Service Manual

19-inch Color Monitor B1996NST /NSL

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Service Manual Versions and Revision

No. Ve rsion Re le as e Dat e Re vision

1. 1.0 Oct. 7, 1999 Original releas e

copied, photocopied, reproduced, translated, or converted to any electronic or machine readable form without prior written permission of LiteOn T echnology Corp.

B1996NST/NST Service Manual.

Printed in Taiwan.

T rademarks

LiteOn is a registered trademark of LiteOn T echnology Corp.

All other trademarks are the property of their respective owners.

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B1996NST/NSL

Table of Contents

1. Precautions.........................................................................................................2

2. Product Specifications .......................................................................................5

3 Control 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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B1996NST/NSL

1 Precautions

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 CR T 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.

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.

Figure 1-1. Set Up For AC Leakage Current Check

5. The CRT is especially constructed to limit Xray 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

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To kno w n

earth ground

0.15ufd

1500 ohm 10 watt

To ex posed m e tal

cabinet part

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, equivalent to 0.2 milliampere AC. Any value exceeding this limit ill constitute a potential shock hazard and must be corrected immediately.

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B1996NST/NSL

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 unforeseen conflict 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 and make 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

Puncture test model PM5530 ADT or KIKUSU TOS-8750 voltage tester or equivalent approved equipment.

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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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 lighten, 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.

B1996NST/NSL

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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B1996NST/NSL

2 Product Specifications

2-1 Specifications

19-inch, (18-inch visual image area) sloted mask, 90

Picture Tube

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

degrees deflection, dot type black matrix, medium short

persistence phosphor, dark tint, non-glare/ anti-static

screen,

0.26 mm dot pitch

Display Color s Analog Input

Synchronizatin Signals

Synchronization Frequencies

Signal Connectors 15-pin, D-shell connector Video Signals Analog : 0.7 Vp-p, RGB positive Power Input 130 Watts (maximum) AC rated voltage, 100VAC to 240VAC Misconvergence Center Area : <

Us er Control s

Service Controls PWB-1465/1466 : power voltage adjust (VR801),

Unl i mit ed Co lor s

Separate Sync: horizontal/vertical, TTL, positive or

nega ti ve Horizontal : 30 to 95 kHz

Vertical : 55 to 160 Hz

0.3 mm; Corner Area : < 0.4mm

Powe r On/ Off, Contras t, Brightness, Hor izontal Si ze, Horizontal Position, Vertical Size, Vertical Position, Pincushion, Trapezoid, Pin Balance, Parallelogram, Rotation, Color temperature, Language, Display Frequency, Degauss, Recall, H. Moire, V. Moire

high voltage adjust (VR101), focus1, focus2

Preset Modes 14 (see Table 2-2. Timing Chart)

Environmental Considerations

Operation temperature : 5 Operation Humidity : 20% to 80% ambient Storage temperature : -40 Storage Humi dity : 5% to 95% (non-condensing)

Altitude : up to3000m above sea level

C to 40oC ambient

C to 65oC ambient

Note: Above specifications are subject to change without prior notice.

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2-2 Signal Cable Pin Connections

Table 2-1. Signal Cable Pin Assignments

Pin Sig nal Pin Signal

1 Red video 9 +5V 2 Green video 10 Digital Ground 3 Blue video 11 Ground

4Ground 12SDA 5* NC 13 H-Sync 6 Re d ground 14 V-S ync/ VCL 7 Green gr ound 15 SCL 8 Bl ue gr ound

B1996NST/NSL

Note: * This pin is used for selftest detection. Connect this pin to ground at the PC end.

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B1996NST/NSL

2-3 Timing Chart

This section describes the timings that the computer industry recognizes as standard for computer-generated video signals.

T able 2-2. Timing Chart

Mode 1 2 3 4 5 6 7 8 9 10 1 1 12 13 14

H. Dot s

V. D o t s

H-fre q (kHz) Sync

Polarity A pe rio d us

B Blking us

C Sy nc us

D B.P. us

E Active us

F F. P. us

V-fre q (Hz) Sync

Polarity O Period ms

P Blking ms

640 640 720 640 800 832 800 1024 1152 1024 1600 1280 1280 160 0

480 480 400 480 600 624 600 768 870 768 1200 1024 1024 1200

31.47 37.5 37.927 43. 27 46.885 49.725 53.67 60.03 68.681 68.67 75 80 91.146 93.75

----+ - ++-+-+++

31.78 26.7 26.366 23.11 21.333 20.11 18.631 16.66 14.56 14.561 13.333 12.504 10.971 10.667

6.356 6.349 6.085 5.33 5.172 5.586 4.409 3.657 3.04 3.725 3.457 3.022 2.844 2.765

3.81 2.032 2.028 1.556 1.616 1.117 1.138 1. 219 1.28 1.016 1.185 1.067 1.016 0.948

1.907 3.81 3.042 2.22 3.232 3.91 2.702 2.235 1.44 2.201 1.877 1.837 1.422 1.501

25.42 20.317 20.282 17. 78 16.162 14.524 14.222 13 11.52 10.836 9. 877 9.481 8.127 7.901

0.636 0.508 1.014 1. 556 0.323 0.559 0.569 0.203 0.32 0.508 0.395 0.119 0.406 0.316

59.94 75 85 85 75 74.55 85 75.03 75.062 84.99 60 75 85 75

--+-+-++-+-+++

16.68 13.3 11.759 11.76 13.33 13.414 11.756 13.33 13.322 11.765 16.667 13.329 11.761 13.333

1.43 0.533 1.213 0.67 0.533 0.864 0.578 0.533 0.656 0.582 0.667 0.525 0.527 0.533

Q Sync ms

R B.P. us

S Active us

T F.P. us

0.064 0.08 0.079 0.069 0.064 0.06 0.056 0.05 0.044 0.044 0.04 0.038 0.033 0. 032

1.02 0. 427 1.107 0.578 0.448 0.764 0.503 0.466 0.568 0.524 0.613 0.475 0.483 0.491

15.25 12.8 10.546 11.09 12.8 12. 549 11.179 12.8 12.667 11.183 16 12.804 11.235 12.8

0.35 0. 027 0.026 0.023 0.021 0.04 0.019 0.017 0.044 0.015 0.013 0.013 0.011 0.011

Horizontal

Video

Sync

H.Parameters:

A: Period B : Blanking T ime C: Sync Width D: Back Porch E : Active Time F : Front Porch

Seperate Sync

Vertical

V.Parameters:

G: Period H :Blanking Time I: Sync Width J : Back Porch K: Active Time L : Front Porch

Video

Sync

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B1996NST/NSL

2-4 Display Power Management Signal (DPMS)

Note: These power-saving states exceed the Environmental Protection Agency (EPA) Energy Star

requirements and the Video Electronics Standard Association (VESA) for Display Power Management Signal (DPMS) .

T able 2-3. Display Power Management Signal (DPMS)

State LED Color H-Sync V-Sync Power

Co ns umptio n

ON Green Pulse Pulse Normal

STANDBY Yellow No Pulse Pulse <10 watts

SUSPEND Yellow Pulse No Pulse <10 watts

OFF Amber No Pulse No Pulse <5 watts

2-6 TCO Version (Optional)

The monitor meets the TCO 99, NUTEK energy saving, electric and magnetic field requirements.

2-6-1 TCO 99 Version (Optional)

The emission from magnetic and electric field must comply with the limits specified by the Swedish Board for Measurement and T esting, commonly known as MPR 1990 recommendations. These limits are summarized in the T able 2-4.

T able 2-4. TCO 99 Requirements

OCT/FLVOCT/FLE

dleiFcitengaMTn52Tn002

dleiFcirtcelEm/V1m/V01

egnaRycneuqerFzHk004~2zH0002~5

eulaVSMRSMR

ecnatsiDmc03mc03

citatsortcelE

laitnetoP

V005-/+V005-/+

The monitor is designed with selected CRT and carefully routed wires around CRT, make sure exactly the same routing scheme is used when doing CR T replacement.

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B1996NST/NSL

The TCO 99 scheme is for international and environmental labelling of personal computers. The labelling scheme was developed as a joint effort by the TCO (The Swedish Confederation of Professional Employ ees), Naturskyddsforeningen (The Swedish Society for Nature Conservation) and NUTEK (The National Board for Industry and T echnical Development in Sweden).

1)`Scope TCO 95 touches on ergonomic qualities, emissions (electrical and magnetic fields), energy efficiency and

ecology (with demands for environmental adaptation for both the product and the production processes at the manufacturing plant).

2) Environmental Requirements The monitor abides by the environmental demands concerning restrictions on the presence and use of

heavy metals, brominated and chlorinated flame retardants, CFCs (freons), and chlorinated solvents, among other things. The monitor is also recyclable.

3) Energy Requirements The monitor also follows the energy requirements that, after a certain period of inactivity, the monitor

shall reduce its power consumption to a lower level in one or more stages.

4) Others The monitor meets the strict environmental demands for the reduction of electric and magnetic fields,

physical and visual ergonomics and good usability.

Table 2-5. TCO 95 Visual Ergonomics

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ytiraeniLsselro%1 ehtotderapmocsworrosnmulocfohtgnelniecnereffiD

.rotinomehtforetnecehthguorhtshtgnelgnidnopserroc

ecnanimuLyalpsiD)tsaelta(2m/dc001

ecnanimuL ytimrofinU

erutarepmetroloC

noitairav

morfsnoitcelceR

gnisac

£G 'v'u¡Ø 10.0

¡Ù /%02¡Ø ssalg03.elbat&tenibacnosinoitarnoitcelferehT

sselro1:5.1 ehtnihtiwecnanimulnimotxamehtneewtebsioitarehT

.aeraevitcaelohw

2-6-2 TCO 99 Version (Optional)

TCO 99 will append the color temperature specification.

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3 Control Location and Functions

B1996NST/NSL

(1)

(2) (3) (4)

(5) (6)

(1) Function Key (2) Decrease Key (3) Increase Key (4) Select Key (5) Power LED (6) Power ON/OFF

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, standby, suspend or 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. But to enter the internal adjustment menu, keep pressing (1) & (4) key simultaneously and then press (6) key.

3. To select a user control, press (2) or (3) key repeatedly until the control is highlighted.

4. To adjust the value for 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.

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B1996NST/NSL

4 Operation 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 NT68P61AU processor-- that has I

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.

C bus controlled geometric correction, contrast and

In addition, it also offers more functions as: (a) Sync. processor, I/P and O/P, (b) Mute, (c) Power saving

- Suspend & Stand-By, (d) Power saving override, (e) DDC1/2B, (f) I

C Bus for auto-alignment through

signal cable (g) CS switching for linearity and size compensation.

3. Stores up to 14 factory preset modes and offers 7 user modes. There are 16 function icons in OSD. They

are controlled by

2 keys on front panel.

4. Powerful PHILIPS TDA4856 and TDA4861 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 NT68P61AU CPU. It contains a 6502 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, 2channel 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 4856 and some DAC in CPU, above operation takes about 500 ms.

2. There allows 14 factory preset modes and 7 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 A TE 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

2 keys, they are detected by

sensing the voltage through R710, R713, R714, R709, R711, R712 to pin 14 and 15 of I701.

4-3 Deflection Section

1. I2C -- autosync deflection controller is TDA4856.

2. The TDA4856 is a high performance and efficient solution for autosync monitors. All functions are

controllable by I control all functions.

C bus. SDA and SCL signals come from microprocessor feed to pin 19 and pin 18 to

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B1996NST/NSL

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 comes into pin 15 through R494. And horizontal flyback pulse comes into pin 1 through R479 and by pass 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.

4-3-2Vertical Section

1. V ertical sync comes into pin 14 through R493.

2. The free running frequency is determined by R470 and C442.

4-3-3Vertical 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 TDA4861.

2. The TDA4861 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, 40V at pin 8, -12V at pin 6)

4-3-4E-W/T rapezoid and H. W idth 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 TDA4856 pin 6 (B DR V) will drive the step down circuit to change H. width.

3. EW DRV (pin11) provides a complete EW drive waveform including parabola, corner and trapezium 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.

4-3-5X-Ray Protection

1. To avoid X-ray hazard, a DC voltage generated by pin 6 of FBT and rectified by D107, C1 11 and divided by R476, R477 and R478 come into pin 2 of TDA4856.

2. If this voltage is higher than 6.39 V, then TDA4856 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 G1, Blanking and Brightness

1. The vertical blanking signal comes from two ways. One is from pin 17 of I401 (TDA4856), the other is from vertical sync (pin 33 of I701). These two positive vertical pulses through Q110 amplified and converted into negative pulse and sent to G1 for vertical blanking.

2. In protection mode or an out-of- range situation HUNLock will send 5 V pulse to saturate Q108 and to cutoff Q107, then G1 will go down to -130V. During the mode change, Mute acts as same as HUNLock’ s.

3. The brightness is controlled by CPU pin 3 through PNP transistor Q107. Q107 is a switch in conducted (ON) status normally. The lower or higher control voltage will get low brightness or high brightness.

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B1996NST/NSL

4-3-7 Contrast Section

1. Contrast is controlled by I701 through I2C bus to I501 (M52743BSP) directly.

2. Beam current is detected through T402 (FBT) pin 7, D106, C109, Q105, R118, R117, R122 to control

I501 pin 15 voltage. When I501 pin 15 voltage drops below 5V, the ABL function will happen.

4-3-8Dynamic focus circuity

The dynamic focus is applied to improve the corner focus performance, it includes horizontal and vertical dynamic focus.

1. Horizontal and vertical dynamic comes from I401 pin 32 and amplified through C106, Q120, Q119, C105,

and feed to FBT dynamic focus pins R111, Q103, Q102, Q101.

2. This amplifier need 890V voltage supply, it comes from FBT pin 2 and rectified through R184, D101,

D120 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, C807, T801, T802 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

indications.

2. Normal : Green light

Amber LED is off because P803 get voltage from FBT through R824, Q801, R846, Q807 to turn off amber light, only green LED is turned on.

3. Standby / Suspend : Y ellow light

Green and amber LED are turned on. That is yellow.

4. Off Mode : Amber light

Green LED is off and amber is illuminated. Green LED is off. Because power supply is off, only LED is turned on.

4-4-4 Auto Degaussing

When S801 turns on, pin 10 of I701 will send a signal to Q802 and turns on RL801 for degaussing. After 4 seconds, it will turn off RL801 automatically.

4-4-5PWM Control

1. Start Up

The I801 (KC3842A) gets power from R831, R830, C812 and pin 7 voltage reaches 16 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.

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B1996NST/NSL

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 R821 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.

4-4-6 Synchronization

1. Normal Mode The sync pulse from FBT (31 kHz~95 kHz) via C815, R826, D824, C814 and R816 to pin 4 of I801 to

keep I801 synchronized with horizontal sync input frequency.

2. Power Saving Modes: Standby/Suspend Because there is no pulse from FBT, so the free-run frequency is decided by R817 and C814 and the

SMPS works at 22 kHz.

3. Override The horizontal free run frequency is about 62.5 kHz under override condition, SMPS is synchronized to

this frequency.

4-4-7 O.V.P.

If the auxiliary voltage is higher than zener voltage ZD807 (18 volts) and makes pin 3 of I801 higher than 1 V, pin 6 duty cycle is limited to have the OVP activated.

4-4-8 O.P.P.

The excess current of T802 through R813, R814, C813, R865 and R864 can develop enough voltage on pin 3 then limit the power delivered because the pin 6 duty cycle is limited too.

4-4-9High Voltage Generation with F.B.T.

1. The H. V generated circuit combines T101 F.B.T. with I101 TL494/KA7500 PWM control circuit.

2. When I101, Vcc(pin12) reaches above 12V, pin 5,6 gets freerun sawtooth waveform about 25KHz and above 5.7V, pin 15’ s voltage will higher than pin 16 (5V constant) than release pin 3 to be controlled by pin 1 feedback signal and compare with pin 5 to output PWM.

3. HFLB1 is used triger pin 5 via Q112, to synchronize the deflection circuit.

4. PWM output to drive Q116, T101 gererate high voltage (26KV) and T101 pin 11, 15 becomes DC/AC feedback, positive the voltage link to I101 pin 1 non-inverting input to stabilize H.V (26KV) and VR101 be adjusted to control H.V value.

5. When X.R.P occur, the hunlock will keep high to pull down I101 pin 2 and shut down PWM output.

4-5 Video Amplifier Section

1. RGB signal inputs are terminated by R501, R531 and R561 then pass through the coupling capacitors C501, C502, C531, C532, C561 and C562 to the IC501 M52743 preamplifier.

2. The amplifier RGB signals (0~4 Vpp) are adjusted by I comes from pin 16 of TDA4856 and through Q502 and Q503 to set up the equal clamp level.

3. The video output stages are amplified by I901(LM2402). The RGB cathodes cut off are adjusted by I bus control by internal icon.

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C bus from I501, pin 19 is for clamp pulse which

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B1996NST/NSL

5. Under override condition, “CHECK SIGNAL” will show on the screen.

4-6 OSD (On Screen Display) Circuit

1. The I502 MTV021 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,d 14, 13, and 12 feed into I501

pin 2,3,4, and 1, then the OSD picture appears.

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B1996NST/NSL

5 Alignments and Adjustments

This section of the service manual explains how to make permanent adjustments to the monitor settings.

5-1 General Adjustments

5-1-1Adjustment Conditions

a) Power Supply

Apply AC 115 V or 220 V

b) Warm-up T ime

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 (IBM PC with proper display cards or Chroma 2250//2225)

6. Screwdriver

5-1-3Switching 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 SXGA (1280 x 1024 @ 91 kHz/85 Hz) signal to the monitor.

3. Connect a DC voltage meter to TP001 end, and adjust VR801 for 14.5

4. If a fuse is broken during adjustment, remember to replace it with the exact same type of fuse.

+ 0.1 V DC

b. If necessary, follow the following procedures to enter the factory mode.

1. Press both

Now, we are in the factory preset mode.

2. When turns the power off, monitor will go back to normal mode (user mode).

3. When you used A TE adjustment future, you should switch S705 to ATE (Factory Position). When you

finish the adjustment, please switch S705 to DDC (normal) position to back normal mode.

key and 2 key simultaneously then power on.

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5-2 Alignment Procedures

5-2-1High Voltage Adjustment

CONDITION

Display image : Crosshatch pattern

PROCEDURE

Connect DC meter to TP5 and adjust VR101 to obtain a DC voltage of -136 ± 0.5V DC.

5-2-2Screen and White Balance Adjustment

CONDITION

B1996NST/NSL

Press

and 2 buttons simultaneously when switching the power “On”.

Display image : No video

PROCEDURE

1 Raster color setting 1-a Set brightness maximum through OSD menu to -21.5 V at G1. 1-b Adjust VR102 to set G2 at 620 ± 5V 1-c Select OSD icon to R.G.B. cutoff 1-d Set G gun cutoff to 0.6 ± 0.15 FL 1-e Adjust R/B cutoff to get x=280 ± 5, y=280 ± 5, Y=0.8 ± 0.2 FL 1-f Set brightness to cutoff , adjust G1 TO get Y<=0.06 1- g Set brightness to minimum, adjust G1 to -38.5V CONDITION Display image : 50 mm x 50 mm white block pattern

PROCEDURE

2 6500

K color temperature setting 2-aSet brightness to cutoff and contrast to 75 Value 2-b Move cursor on OSD to choose color temperature icon. 2-c Press

key to G gain then adjust G gain = 47 value, then adjust B, R to x=313±5, y=329±5.

2-d Check x=313±5, y=329±5.

3 9300

K color temperature setting 3-a Move cursor on OSD to choose color temperature icon. 3-b. Press

key to G gain then adjust G gain = 50 value, then adjust B, R to x=283±5, y=297±5.

3-c Adjust contrast max. to set Y=37±2FL 3-d Check x=283±5, y=297±5. 3-e Adjust contrast min. to set Y=1.0FL. 4 Full white ABL setting

CONDITION

Display image : full white pattern 4-a Set brightness to cutoff and contrast to maximum. 4-b Move cursor to choose ABL icon.

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B1996NST/NSL

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, then power off.

5-2-3Focus 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.

5-2-4Dynamic focus Adjustments

1. Horizontal dynamic focus set Hf=350V ±10 V in phase (compare with Vcp signal).

2. V ertical dynamic focus set Vf=145V ±10V in phase.

5-2-5Static 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

Display image : Crosshatch pattern W arm-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.

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Figure 4-1. Convergence Magnets on the CRT

B1996NST/NSL

CRT

FRONT

8 7 6 5 4 3 2

1) Setup Bolt 2) Bow Magnet 3) Band 4) 2-Pole Magnet

5) Spacer 7) Spacer

9) Holder

6) 4-Pole Magnet

8) 6-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

Red/ Bl u e Gre en

6-pole magnets movem e nt

Blue Red

Bl u e Re d

Red/ Blue

Green

4-pole magnets movem e nt

Note : The 4-pole magnets and the 6-pole magnets interact, making dot movement complex.

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B1996NST/NSL

5-2-6 Degaussing

Degaussing is required when poor color impurity appears on the screen. This monitor uses an automatic degaussing circuit that is activated when the power is on. The automatic degaussing will be fully functional again after the monitor has been in operation for 20 minutes.

The degaussing effect is confined to the picture tube since the coils are mounted at the back of the tube. Should any part of the chassis or cabinet becomes magnetized, it is necessary to degauss the affected area with a manual degaussing coil.

5-2-7 Manual Degaussing

1. Apply line voltage to the degaussing coil and move it in a rotary motion over the front, sides, and top of the monitor. The coil should be kept away from the rear of the monitor to avoid damaging the magnetic neck components.

2. Slowly rotate and move the coil away from the monitor to about 6 feet beyond the point where no effect on the CR T will be noticeable.

For proper degaussing, it is essential that the field be gradually reduced by moving the coil slowly away from the monitor. The degaussing coil must never be shut off or disconnected while near the monitor, as this would introduce a strong field instead of canceling the effect of the stray fields.

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6 T roubleshooting

6-1 No Raster

B1996NST/NSL

No Raster

Measure

voltage of B+ at

T402 pin 2 on

PWB-MAIN

0 V

Short Circuit

at load?

Yes

Check DC B+ line,

Q411, D817

(121 V, 91kHz)

Check voltage of

Check AC I/P on

Check I801,

Q803, R814,

R813, ZD807,

ZD801, R831,

R830, R818

cathode, heater, Grid

C808

Yes

Normal

1, Grid 2, etc.

D801,T801,

R804, T804,

High

(75 V or more)

Check I401

Check

F801

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6-2 OSD Abnormal

B1996NST/NSL

OSD Abnormal

Check I502

missing?

Check R530,

R532, R531

OK?

Yes

Check JP806, L504,

L505 OK?

Yes

Put on

I502

Replace them

Replace it

Page 22

Replace I502

Page 25

6-3 Function Key Abnormal

Function Key Abnormal

B1996NST/NSL

Check I701 and

I703 missing?

Power

ON/OFF again and

check X701, oscillator

OK?

Yes

Check

I703 EEPROM content

OK?

Yes

Put on

I701, I703

Replace X701

Replace I703 or do

ATE again

Replace I701 and check

uP OK?

Check

pin 5 of I701

is 5V?

Replace I804

Yes

Replace I701

Check

R735, C710

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6-4 No Vertical Scan (Raster is one horizontal line)

No Vertical Scan

Check I301 voltage

of pin 1 is 12V, pin 8

is 40V and pin 6 is

12 V?

Yes

B1996NST/NSL

Ckeck or replace

I301.

Check

pin 5 O/P waveform at

I301

Normal

Check

pin 2, 3 of I301

waveform

Still no vertical scan

Check or replace CRT

Abnormal

Replace I301

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6-5 Out of Horizontal Synchronization

Out of Horizontal

Synchronization

B1996NST/NSL

Horizontal sync present at pin 15 of I401

Yes

Check

I401 pin 8 H output

frequency

Yes

Check Q401, T401, Q402, R402, R403,

L401, L402, D402

6-6 Out of Vertical Synchronization

Out of Vertical

Synchronization

Ckeck or replace

the signal cable or

I701

Check or replace

the signal cable

or I701

Vertical sync

present at

pin 14 of I401

Yes

Check

I401 pin 24 ramp

frequency

Check C442

Ckeck signal cable &

vertical sync input &

I701

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6-7 R.G.B. Video Amplifier Abnormal

RGB Video AMP Abnormal

B1996NST/NSL

Check

waveform at I501 pin 29, 32

and 35

Yes

Check

I901 pin 1, 3 and 5 voltage

and wave form

Yes

Video signal present at the

pin of the CRT R.G.B.

Cathode

Yes

Check or replace the

signal cable or I501

Check Q961,

Q901, Q931

Page 26

Defective cut-off circuit

(DC restore)

Page 29

B1996NST/NSL

7 Recommended Parts List

Note: The components identified by “ “ mark are critical for X-ray safety. Replace these with

exactly the same parts specified.

No. Loca t ion P art Number Des c ription

1 C407 6325943252-03 P=22.5 PPS 4300P 1800V 2 C808 6312633126 ALU uF 330 400V F 85C 25x40 3 D801 6417001000 TS4B05G-01

5 D407 6412018300 DIODE SM3AP4 3A/ 400V ORIGIN 6 D831 D813 6412002937 DIODE FUF 5407AMP 3A/800V 7 D817 D119 6412018400 DIODE SM3AP6 3A/600V ORIGIN 8 F801 6851504053 / 51 FUSE TIME LAG 5ST4 4A/250V 9 I301 6442027200 IC TDA4861 9P (PHILIPS)

10 I401 6442025200 IC TDA4856 32P SDIP (PHILIPS)

11 I501 6442024210 IC M52743 BSP 36P MITSUBISH) 12 I701 6448014500 IC NT68P61AU 40P PDIP OTP NOVAT 13 I703 6448007930 IC 24C04 SAMSUNG 14 I801 6442022000 IC KA3842AC 8P PDIP (SAMSUNG) 15 L404 6139000200 COIL CHOKE 8mH K DRWW

D814 D815 D402

6412020007 DIODE SF34 3A/200V

16 Q402 6421004310 TR NPN 2SC5411 (TOSHIBA) 17 Q404 6427000900 FET P- CHNL SFS9634 18 Q116 6426005410 FET N-CHNL IRFS840A 19 Q115 6426006400 FET N-CHNL IRFS630A SAMSUNG 20 Q803 6426001720 FET N- CHNL 2 SK2761 FUJ I 21 R803 6203459017 POSISTOR 4.5 OHM Q 2PINPITCH=10 22 R804 6201100062 THERMISTOR 10 OHM 5A P=7.5 TKS 23 R818 6220327852 FS OHM 0.27 1W J HOR 24 T401 6135003400 XFRMR HOR DRIVE THD-1034 EI19

Page 27

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B1996NST/NSL

No. Location Part Numbe r Description

25 T101 6133096010 FBT TFB- 9601 FEA883 SAMPO

26 T402 6111444130 COIL CHOKE 4.4MH

27 T801 6138002201 LINE FILTER TLF-1016A 16mHET28

28 T802 6131060920/910 XFRMER PWR TPW-1072 EE40

29 X701 6449000719 CRYSTAL 8MHz TOP8.000 30pF TOP

30 I901 6442025000 LM 2402 11P

31 I402 I902 6442005900 LM324 14P

32 I804 6442000830 KA7805

33 I805 6442000430 KA7812

34 I807 I802 6442014000 IC LTV-817D

35 I803 6442011610 IC SPQ01A 8P

36 Q101, Q102 6421003100 2SC4686A

37 R813 6221215852 0.15 OHM 2W

38 I702 6448007430/420 24LC211 / / AT24C21

39 D818 6412019907 SF24

41 Q411 6424003300 KSB772

42 C413 6326212456 MPP 0.12U 250V

43 C421 6326210453- 03 MPP 0.1u 250V

44 C423 6326222457-03 MPP0.22u 250V

45 C425 6326356442 MPP 0.56u 400V

Q406 Q410 Q403

6421003800 KSD882

46 C427 6326312542/56 MPP 1.2u 400V/ MPP/1.2U 250V

Page 28

Page 31

8 Block Diagram

SDA1

RGB

I502

MTV021-21

OSD

SDA 1

SCL 1

SCL1 ABL

HFLB1 VTTL

CLBL

M52743

VIDEO PREAMP

12V

B-IN

R-IN

G-IN

LM2402

LM324

I902

R G B

HEATER

G1 G2

FOCUS 1

FOCUS 2

B1996NST/NSL

P901

P501

SCL SDA

DDC 5V

LED

SDA

S705

I803

SPQ1A

V SYNC H SYNC

BRIGHTNESS

CONTROL

FACTORY

ATE

SCL NORMAL

DDC

OFF

O/R SCL SDA

KEY

SCL SDA

I701

NT6861 AU

I702

24C21

P903

VTTL HTTL SCL1 SDA1

RESET

CKT R735 C710

STAND-BY

SCL1

DEG.

E2PROM

I703

2404

REGULATOR

SDA1

DEG CKT

6.3V

QI804

12V

80V

GND

I401

TDA 4856

12V

145V

GND

I101

PWM CONTROL

TL494/KA7500

VOUT 1 VOUT 2

XRP

VERTICAL

O/P

I301

H DRIVER

Q402 D403 C407

B+

DRIVER

Q404 T402

180V

-12V

Q116

FBT

DRIVER

Q115

CANCELING

CKT

HFLB1

48V

12V

T101 FBT

BRIGHTNESS

CONTROL&

SPOT KILLER

LINEARITY

CONTROL

T403

H CENTER

Q403

VR401

145V

G2 CONTROL VR

P301

-H

-V

48V

-130V

ABL CONTROL CKT Q105

XRP CKT

LINE

FILTER

BRIDGE

DIODE

SMPS

LOW VOLTAGE

DROP DOWN

POWER

O/P

T802

-12V 80V

180V

12V

12V SWITCH

Q813

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