LITE-ON A1996 Service Manual

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Service Manual

19-inch Color Monitor A1996NST

Page 2

Service Manual Versions and Revision

No. Version Release Date Revision

1. 1.0 Dec 3, 1997 Original release

2. 1.1 Oct. 30, 1998 8-1 (b)

3. 1.2 April 30, 1999 2-1 Pow er Input-120 W (TOSHIBA CRT)

Pow er Input-130 W (SAMSUNG CRT)

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

A1996NST Service Manual.

Printed in T aiwan.

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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A1996NST

Table of Contents

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

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

3. Operation Theory............................................................................................. 10

4. Alignments and Adjustments ........................................................................... 14

5. Troubleshooting............................................................................................... 18

6. Recommended Spare Parts List....................................................................... 22

7. Block Diagram ................................................................................................ 24

8. Exploded Diagrams..................................................................................Inserted

9. PCB Diagrams ......................................................................................... Inserted

10. Schematic Diagrams ................................................................................ Inserted

T roubleshooting

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1 Precautions

Please 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.

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

To kn own

earth

round

0.15ufd

1500 ohm 10 w att

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.

PrecautionsPage 2

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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 unconnected.

Precautions

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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.

A1996NST

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.

PrecautionsPage 4

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2 Product Specifications

2-1 Specifications

Picture Tube 19-inch (18- inch Visual image area), 90 degrees deflection, dot type black

matr ix, medium short pers istence phos phor, dark bulb,dir ect etch, Fl at square screen with Invar Mask,

0.26 mm dot pitch

Sc anni ng Fr eq uenc y

Maxi mum Re solution 1600 dots (H) x 1200 lines (V) @75 Hz refresh rate

Di spl ay Ar ea 35 0±4 mm (H) x 262±3 mm (V) typical

Display Characters 80 char. x 60 rows on a 10 x 10 matrix

Di spl ay Co lo rs Anal og Input

Sync hr oni zat in S i gnal s Se pa ra te Sync : ho r iz onta l /v er ti c al , TTL, pos i ti ve or ne gati v e

Sync hr oni zat io n

Frequencies

Signal Connectors 15-pi n, D-s hel l connector

Video Signals Anal og : 0.7 Vp-p, RGB positive

Power Input 120 Wa tts (maximum- TOSHIBA CRT) AC r ated voltage, 90VAC to 264VAC

Mi sconvergence Center Area : <

VGA, Super VGA, 1024x768@60/70/ 75/85 Hz, 1280x1024@60/75/ 85 Hz,

1600x1200@60/75 Hz

Unl i mi t e d C o l or s

Horizonta l : 30 to 95 kHz Ver tical : 50 to 120 Hz

130 Wa tts (maximum- SAMSUNG CRT) AC rated voltage, 90VAC to 264VAC

0.2 mm; Corner Ar ea : < 0.4mm

Use r Co ntr ol s Po we r On/ Off , Co ntr as t, B ri ghtne ss , Ho ri zont al Si ze, Hor i zont al Pos i ti on,

Verti cal Sizs, Vertical Posi tion, Pincushion, Tr apezoid, Rotation, Unbalance, Parallelogram, Degauss, Corner, Recal l, V. Mo i r e, H. Mo i re

Servic e Controls PWB-1385 : power voltage adjust (VR801),

high voltage adjust (VR101), F1/F2/ G2 ( FBT)

Preset Modes 12 ( see Tabl e 2-2. Timing Chart)

Envir onmental

Consider ations

Operation temper ature : 10

Humidity : 20% to 80% ambient Storage temper ature : 0 Storage Humi dity : 10% to 95% ( non-condensing)

Altitude : up to3000m above sea le ve l

C to 35oC ambient

C to 65oC ambient

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

Product Specifications

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2-2 Signal Cable Pin Connections

Table 2-1. Signal Cable Pin Assignments

Pin S ignal Pin Signal

1 Red video 9 NC 2 Green video 10 Ground 3 Blue video 11 Ground

4 Gro und 1 2 SDA

A1996NST

13 H-Sync 6 Re d gr ound 14 V- Sync 7 Gr ee n gro und 15 SCL 8 Bl ue gr ound

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

Product SpecificationsPage 6

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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 123456789101112

H. D ots 640 640 640 720 800 800 1024 1024 1280 1280 1600 1600

V. D o t s 480 480 480 400 600 600 768 768 1024 1024 1200 1200

H-freq (kHz) 31.47 37.5 43.27 31.47 46.885 53. 67 60.03 68.67 80 91.14 6 75 93.75

Sync Polarity -- - - ++++++-+

A pe riod us 31.78 26.7 23.11 31.78 21.333 18.631 16.66 14.561 12.504 10.971 13.333 10.667

B Blking us 6.356 6.349 5.33 6.356 5.172 4.409 3.657 3.725 3.022 2.844 3.457 2.765

C S ync us 3.81 2.032 1.556 3.81 1.616 1.138 1.219 1.016 1.067 1.016 1.185 0.948

D B.P. us 1.907 3.81 2.22 1.907 3.232 2.702 2.235 2.201 1.837 1.524 1.877 1.501

E Activ e us 25.42 20. 317 17. 78 25. 42 16. 162 14. 222 13 10.83 6 9.481 8.1 27 9.877 7.901

F F. P. us 0.636 0.508 1.556 0.636 0.323 0.569 0.203 0.508 0.119 0.305 0.395 0.316

V-freq (Hz) 59.94758570758575.0384.9975856075

Sync Polarity -- -+++++++ -+

O Period ms 16.68 13.3 11.76 14. 27 1 3.33 11.756 13.33 11.76 5 13.329 11.76 1 16.667 13.33 3

P Blk ing ms 1.43 0.533 0.67 1.557 0.533 0.578 0.533 0.582 0.525 0.527 0.667 0.533

Q Sy nc ms 0.064 0.08 0.069 0.064 0.064 0.056 0.05 0.044 0.038 0.033 0.04 0.032

R B.P. us 1.02 0.427 0.578 1.08 0.448 0.503 0.466 0.524 0.475 0.483 0.613 0.491

S Active us 15. 25 12.8 11.09 12.71 12.8 11.179 12. 8 11.183 12. 80 4 11.235 16 1 2.8

T F.P. us 0.35 0.027 0.023 0.413 0.021 0.019 0.017 0.015 0.013 0.011 0.013 0.011

Seperate Sync

H orizontal

Video

Vertical

Video

Sync

H.Parameters:

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

Product Specifications

Sync

V.Parameters:

G: Period H: Blanking Time I: Sync W idth J : Back Porch K: Active T ime L : Front Porch

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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 nsumpti o n

ON Green Pulse Pulse N ormal

STANDBY Yellow No Pulse Pulse <1 5 watts

SUSP EN D Yellow P ulse No Pulse < 15 wa tts

O FF Amb er N o P ulse N o Puls e <5 w at ts

2-6 TCO Version

The monitor meets the TCO 92, NUTEK energy saving, electric and magnetic field requirements. Also it is compliant with TCO 95 labelling scheme.

2-6-1 TCO 92

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 92 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 for CRT replacement.

Product SpecificationsPage 8

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A1996NST

2-6-2 TCO 95

The TCO 95 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 Technical 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

erutaeFdradnatSnoitpircseD

ytiraeniLsselro%1 ehtotderapmocsworrosnmulocfohtgnelniecnereffiD

ecnanimuLyalpsiD)tsaelta(2m/dc001

ecnanimuL ytimrofinU

sselro1:7.1 ehtnihtiwecnanimulnimotxamehtneewtebsioitarehT

.aeraevitcaelohw

.rotinomehtforetnecehthguorhtshtgnelgnidnopserroc

Product Specifications

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A1996NST

3 Operation Theory

This is an I2C-bus fully digital controlled multi-sync color monitor, compliant with VESA DDC1/2B and DPMS standards. Besides, it also meets TCO95 and MPRII requirements. It provides user friendly OSM (On-Screen display Menu) controls, and offers the following main features.

3-1 Main Features

1. Simplified chassis design with minimum components.

2. Fully digital controlled via 8-bit microcontroller NT68P61A.

3. Auto switching to off mode under “OUT OF RANGE” (Fh < 29KHz or Fh > 97KHz).

4. Reliable chassis design through various internal circuit protections.

5. Universal full range AC input and low power consumption.

6. Five-country OSM language available for easy user controls.

7. Adjustable OSM display time and position.

8. T welve preset modes up to 1600 x 1200 75Hz (Fh =93.75KHz).

3-2 Microcontrol Section

1. The microcontroller provides I2C bus (pin 24 & 25) for geometric controls via I401 TDA4854 and video controls via I501 M52743. The geometric controls include H-size, H-position, V-size, V-position, Pincushion, Pin-balance, Trapezoid, Corner, Parallelogram, H-focus, V-focus, H-moire and V-moire. The video controls cover Contrast, Brightness, R/G/B gain and cutoff control alignments. Through 8-bit PWM’ s (pin 1, 2, 3, 34, 35, 38) it provides factory controls for G1, NS-trapezoid, H-linearity, user control for Rotation and one F/V for H-frequency driver compensation . Three I/O’ s (pin 12, 16, 17) are provided for 3-wire SPI bus used for I502 M35045 on-screen display.

2. In addition, the microcontroller offers Auto Mode detection via Hsync (pin39) and Vsync (pin40) inputs. According to Auto Mode detection, VESA DPMS power saving (pin 28, 29) will limit the output power under 15W for Standby or Suspend mode, under 5W for OFF mode. VESA DPMS mode indication is done via I/O pin 9 & 10 to drive LED display on the front cover. Normal mode displays green LED, Standby or Suspend modes displays Yellow LED while OFF mode displays Amber LED.

3. Auto factory alignment (A TE) and VESA DDC2B communication are through DDC I2C bus (pin 24, 25), I704 24LC211 is dedicated for DDC EDID E2PROM. In order to get optimal H-linearity performance for the full range frequency (31KHz - 95KHz), 4-channel CS are used at pin 19, 22, 23, 24. F1, F2, UP and DOWN function keys’ scanning are through 2 ADCs on pin 13 & 14. Q703 and Q704 delay circuits are used for power-on reset at pin 4. In order to avoid I2C interference during H-size, H-position, V-size, V-position, Contrast and Brightness alignments, the HUNLK from I401 TDA4854 is applied from Q705 inverter to IRQ at pin 15.

4. There are 12 factory preset modes and 8 user modes available. Related information data of those modes are stored at 2 EEPROM’s (I702, I703) 24LC04.

3-3 Deflection Section

1. I2C -- autosync deflection controller is TDA4854.

2. The TDA4854 is a high performance and efficient solution for autosync monitors. All functions are

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A1996NST

controllable by I2C bus. SDA and SCL signals come from microprocessor feed to pin 19 and pin 18 to control all functions.

3-3-1Horizontal Section

1. The oscillator is driven by the currents in R418 and R417. The minimum oscillator frequency is determined

by R418 and the maximum frequency is determined by R417.

2. Horizontal sync comes into pin 15 through R314. And horizontal flyback pulse comes into pin 1 through

C428, C429, R403 and bypass filter C401 from Vcp of Q416 collector for AFC loop.

3-3-2 Horizontal O/P Section

1. Horizontal driver (pin8) signal is sent to Q417 via R482, C434.

2. Signal from Q417 direct drive T403, through R488 (shunt with R481) and L404 (shunt with L405) to

horizontal output transistor Q416.

3-3-3 Vertical Section

1. V ertical sync signal from micro controller is connected to pin 14 through R313.

2. The free running frequency is determined by R317 and C312.

3-3-4Vertical 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 1 and pin 2 of TDA8351.

2. The TDA8351 has two output stages which are current driven in opposite phase and operate in combination

with the deflection coil in a full bridge configuration.

3-3-5 E-W/T rapezoid and H. Size Controls

1. The B+ driver for step down circuit is from pin 6, it provides 20~80% duty cycle outputs according

to H-frequency.

2. The E/W / Trapezoid and H-size controls are through B+ modulation at I401 TDA4854. The EW output

signal is from pin 11, it’s not tracking with H-frequency.

3-3-6 X-Ray Protection

1. To avoid X-ray hazard, a DC voltage generated by pin 3 of FBT and rectified by D107, C113 is divided by

R113, R114 and C447 filter go into pin 2 of TDA4854.

2. If this voltage is higher than 6.39 V , then TDA4854 will be activated to float HUNLOCK (pin 17), H. DRV

( pin 8), B DR V (pin 6), VOUT1 (pin 12), VOUT2 (pin 13). After that all deflection circuit stop working.

3-3-7G1, Blanking and Brightness

1. The vertical blanking signal comes in two ways. One is from pin 8 of I301 (TDA8351), the other is from

HUNLK (pin 17 of I401). These two positive vertical pulses through Q553, Q551, Q555 amplified and converted into negative pulse and sent to G1 for vertical blanking.

Operation Theory Page 11

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A1996NST

2. In protection mode or out-of-range situation, HUNLock will send 5 V pulse to saturate Q706, then pin 8 of I902 will be low state and open Q509, so G1 will go down to -140V. During the mode change, Mute acts as same as HUNLock’ s.

3. The brightness is controlled by CPU, pin 26 and pin 27 comes into pin 20 and 21 of I501, DC level can be changed by I brighter raster, low voltage gets lower brightness.

C bus from 0~5V of D/A output at pin 23 of I501, high voltage causes high current to get

3-4 Power Supply Section

3-4-1 AC Rectifier

The circuit can accept 90 V to 264 V AC input through D801 bridge diode and C810 filtering to get DC 126 V~364 V for power conversion in T804.

3-4-2 Line Filter

It consists of C801, C802, C803, C806, C807, C850, C851, T801 and T802 and meets EMI regulation.

3-4-3 Power LED Status

1. The LED has 3 leads common cathode with green and amber color for different power saving indications. It is controlled by CPU.

2. Normal : Green light Amber LED is off because CPU pin10 is high and pin 9 is low, only green LED is turned on.

3. Standby / Suspend : Y ellow light CPU pin 9 and pin 10 are low, then green and amber LED are turned on. That is yellow.

4. Off Mode : Amber light CPU pin 9 is high and pin 10 is low, then green is off and amber is on.

3-4-4 Auto Degaussing

When SMPS works, the 7 V power source is applied to Q806 and CPU let Q806 turn on a few seconds, then drive the armature of RL801 to perform the degaussing function.

3-4-5 PWM Control

1. Start Up The I801 gets power from R807, R824, R825, C823 and pin 7 voltage reaches 9 V for starting up. The

I801 starts oscillation at 20 kHz, sawtooth on pin 4 and pin 6 output to drive Q802/T804. Once Q802 switches on, D806, R817, C816 set up an 15 V to keep I801 working through D807 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 R837, R838, VR801 and R839 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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A1996NST

3-4-6Synchronization

1. Normal Mode

The sync pulse from FBT (31 kHz~93.75 kHz) via C822, R832, D811, D827 and R878 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 R828 and C822 and the SMPS works at 20 kHz.

3. Override

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

3-4-7 O.V.P.

If the auxiliary voltage is higher than zener voltage ZD803 (18 volts) and makes pin 3 of I801 higher than 1 V, pin 6 duty cycle is limited to have the OVP activated.

3-4-8 O.P.P.

The excess current of T804 through R818 can develop enough voltage on pin 3 then limit the power delivered because the pin 6 duty cycle is limited too.

3-5 HV Supply

1. HV (High Voltage) start up is triggered by H-pls at pin 4 via R163. I102 3843 provides the PWM output

control (pin 6) to drive the step down B+ supplier Q116 via inverter Q119 and buffer Q117 / Q118. This circuit is similar to deflection step down B+ supplier Q405.

2. The ramp generator for I102 pin 3 and I103 pin 2 is from the same H-pls, via R102 and C118 differential

circuit to drive Q120. The time constant is dependent on the value of R112 and C112. I103 LM393 comparator provides the PWM output control (pin 3) to drive Q101 via inverter Q105 and buffer Q106 / Q110.

3. I301 pin 32 provides the H+V composite signals to drive the two-stage dynamic focus amplifier. Output

of vertical amplitude is around 160 Vpp, while output of horizontal amplitude is around 510 Vpp.

Vertical dynamic focus Horizontal dynamic focus

3-6 Video Amplifier Section

1. RGB signal inputs are terminated by R501, R531 and R561 then pass through the coupling capacitors

C502, C532 and C562 to the I501 M52743ASP preamplifier.

2. The amplifier RGB signals (0~3 Vpp) are adjusted by I

pin 16 of TDA4854 to set up the equal clamp level.

3. The video output stages is I901 LM2403, the output resistors R904, R934, R964, R913, R943 and R973

are 47 ohm for arcing protection and the power dissipation is minimized.

4. The RGB cathodes cut off are adjusted by D/A output pins 24, 25, 26 of I501.

Operation Theory Page 13

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

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A1996NST

4 Alignments and Adjustments

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

4-1 General Adjustments

4-1-1Adjustment 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 = 93.75 kHz, FV = 75 Hz, unless otherwise

defined.

4-1-2 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 or equivalent)

6. Screwdriver

4-1-3Switching 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 (1600 x 1200 @ 93.75Khz / 75 Hz) / crosshatch pattern to the monitor.

3. Connect a DC voltage meter to TP003, and adjust VR801 for 14.7 ± 0.1 V.

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 procedure to enter the factory preset mode:

1. At power off mode, turn S702 SW to alignment position close to CRT side.

2.Press both

3.Turn on the power again to return back to normal mode (user mode).

4.After finishing the manual alignment, S702 SW has to be returned back to its normal stage (close to FBT side). Otherwise the DDC can not be read.

key and key simultaneously then power on to enter the factory preset mode.

Page 14 Alignments and Adjustments

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4-2 Alignment Procedures

4-2-1High V oltage Adjustment

CONDITION

Display image : Crosshatch pattern

PROCEDURE

Connect DC meter to TP007 and adjust VR101 to obtain a DC voltage of 152 ± 1V DC .

4-2-2Screen and White Balance Adjustment

CONDITION

A1996NST

Switch S701 to factory mode, then press “ power “On”.

W arm up 30 minutes Mode : 93 KHz / 1600 x 1200 Display image : No video

PROCEDURE

1-aSet brightness to maximum, G1 at “70” OSD-step, and G2=620 V, contrast to maximum.

Select “preset color” then choose “9300°K” 1-b Adjust Green cut-off around “70” OSD-step. 1-cAdjust G1 and R/B cut-off to get 0.8+0.15 / -0.1 FL of raster light output. 1-d Confirm x=281±5, y=311±5.

CONDITION

Display image : 50 mm x 50 mm white block pattern

PROCEDURE

2-aSet brightness to mid-level. 2-b Adjust contrast to maximum. 2-cR/B signal off and adjust green gain to get Y=25 ± 0.2 FL.

” and ” ” buttons simultaneously when switching the

2-d R/B signal on, adjust R/B gain to get x=281±5, y=311±5.

CONDITION

Display image : Full white pattern

PROCEDURE

3-a Set brightness and contrast to maximum. 3-b Adjust “ABL” to 30±1 FL. 4-a Repeat all the procedure in 4-2-2 section until the best white balance is obtained, then power off. 4-b After screen and white balance adjustments, S701 must be switched to Normal mode.

Alignments and Adjustments

Page 15

Page 18

A1996NST

4-2-3Focus Adjustment

CONDITION

Display image : “e” character pattern

PROCEDURE

1. Set brightness and contrast used for a normal display.

2. Adjust the static focus control on the high voltage resistor block to obtain the best focus over the entire display area.

4-2-4 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 of warm-up time for convergence adjustment.

CONDITION

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

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

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.

CRT

FRONT

8) 6-Pole Magnet

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.

Page 16 Alignments and Adjustments

Page 19

Figure 4-2. 4-pole and 6-pole Magnets Movement

Blue Red

A1996NST

Red/ Blue Gree n

Blue Red

4-pole magn ets movement

Red/ Blue

Green

6-pole magn ets movement

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

4-2-5Degaussing

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 manual degaussing will be fully functional after the monitor has been in operation for 20 minutes through OSM degaussing function.

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 external degaussing coil.

4-2-6External 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.

Alignments and Adjustments

Page 17

Page 20

5 T roubleshooting

(

)

(

)

, Q

5-1 No Raster

No Raster

Measure

H volta

e of B+

at T402 on

PWB-MAIN

A1996NST

Check

I401

416, D404

Check

D801

405

Check AC I/P on

T801

Yes

Check

I801

R816, R819

802, D816, D817

D818, D819, D821

0 V

Short Circuit

at load?

Yes

Check DC B+

line

F801

116, Q101

Yes

T101 pin 2 HV

B+

48 V

Normal

40 V, 31.5 kHz

Check voltage

of cathode

heater, Grid

Grid 2, etc.

Yes

Video

0 VHIGH

I102, ZD104

116, Q101

High

50 V or more

Check I401

405, Q404 403, Q432 433, Q434

426

Page 18 T roubleshooting

Page 21

5-2 Function Key Abnormal

pplyRep

Function Key Abnormal

A1996NST

Check 5V from

I804 re

Yes

Power

ON/OFF a

check X701

OK?

Yes

Check

I701 uC OK?

Yes

ulator?

ain and

oscillator

Repair power

lace X701

Replace I701

Check LED LD701 OK?

Yes

END

T roubleshooting

Replace

701 or Q702

Page 19

Page 22

5-3 Vertical Scan (Raster is one horizontal line)

Vertical Scan Abnormal

Check voltage of

pin 3 at I301

(about 14 V)

Yes

A1996NST

Replace I301.

Check

pin 4 or pin 7 waveform

at I301

Normal

Check R308 short ?

Still no vertical scan

Check or replace CRT

Abnormal

Check pin 12 & pin

13 waveform at

I401

Replace I301

Yes

Replace R308

Page 20 T roubleshooting

Page 23

5-4 R.G.B. Video Amplifier Abnormal

RGB Video AMP Abnormal

A1996NST

Check

the waveform at the I501

pin 29, pin 32, pin 35

Yes

Check

the waveform at the

I901 pin 3, 5, 1

Yes

Video signal present at the

pin of the CRT R.G.B.

Cathode

Yes

(pin17, pin36)

Check B+ pin 10, 6

Check B+

Yes

Check the

waveform at pin

2, 6, 11, 19, 27

Check I901

Yes

Check I501

Defective cut-off circuit

(DC restore)

Recommended Spare Parts List

Page 21

Page 24

A1996NST

6 Recommended Parts List

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

only the same parts specified.

No. Location Part Numbe r De s cription

1 C810 6312633166 ALU uF 330 400V F 105C 30x45

2 D801 6417000301 DIODE BRIDGE FBU4K F 4A/800V

3 D816 D821 6412014707 DIODE FUF5406AMP T52 3A/600V

4 D817 6412014307 DIODE BYV26C 113 T52 SOD-57

5 D818 D819 6412002727 DIODE BYW98- 200RL 3A/200V 35nS

6 F801 6851504051 FUSE TIME LAG H-BRK 19181-4A

7 I301 6442011200 IC TDA8351 9P SIL PHILIPS

8 I401 6442020700 IC TDA4854 32P SDIP (PHILIPS)

9 I501 6442024200 IC M52743ASP 36P SDIP MITS UBISHI

10 I701 6448012200 IC NT68P61A 40P PDIP OTP NOVAT

11 I703 6448007900 IC 24C04A/P (MICROCHIP)

12 I801 6442023500 IC KA3843A 8P PDIP SAMSUN G

13 I901 6442021900 IC LM2403 11P TO -220 N S

14 L404 L405 6115229507 CO IL PEAKING 2.2 uH J T52 1/2w

15 L406 6881001507 BEAD CORE W5 RH3.5x6x1.0T

16 Q101 6426007100 FET N- C HNL 2SK1119(TO S HIBA)

17 Q116 Q405 6427000900 FET P-C HNL SFS9634 SAMSUNG

18 Q402 6421000325 TR NPN 2SC 1815-Y(TPE2) TO SHIBA

20 Q416 6421004300 TR NPN 2SC5411 (TOSHIBA)

21 Q802 6426000800 FET N- C HNL 2SK2648-01(FUJI)

22 R403 6212115254 C F KOHM 1.5 1/4W J T26 MINI

Q403 Q420 Q423

6424003005 TR P NP 2SA673ACTZ T/A (HITACHI)

Page 22 T roubleshooting

Page 25

A1996NST

No. Location Part Number Description

23 R404 6212147254 CF KOHM 4.7 1/ 4 W J T2 6 MINI

24 R405 6212368157 CF OHM 680 1/2W J AT52

25 R803 6203459017 POSISTOR 4.5 DGC3D4R5Q27C 3PIN

26 R804 6201100022 THERMISTOR 10 OHM 5A P=7.5 TKS

27 R819 6221215852 MOF OHM 0.15 2W J HOR

28 T401 6119003204 COIL LINEAR DYNAMIC TLN-1032D

29 T402 6111444130 COIL CHOKE 4.4mH K DR16x18 P3B

30 T801 6138002201

31 T802 6138001601 LINE FILTER TLF-1016A 16mHET28

32 T804 6131051500 XFRMER PWR TPW-1063 EE42/15AXI

33 X701 6449000700 CRYSTAL HC49/ U 8MHZ 50ppm 7pF

LINE FILTER TLF-1022A

Recommended Spare Parts List

Page 23

Page 26

7 Block Diagram

A1996NST

19"

CRT

DC RESTORE

RGB BUFFER &

I901

AMPLIFIER

LM2403 CRT

R-OSD

I501

VIDEO

M52743

B-OSD

G-OSD

PRE-AMP

SDA

BRIGHTNESS

SCL

VIDEO

CONTROL

OSD

I502 M35045

SIN

BOARD

SOPT KILLER

BLANKING / MUTING

SCK

ABL

Q116

STEP

DOWN

Q121

180V

REGULATOR

DEFLECTION HV SU

Q405

BDRV

SDA

STEP

DOWN

I401

SCL

T101

TRANS

FLYBACK

CS CRT

H-LIN &

TDA 4854

DEFLECTION

RASTER

CENTER

-136V

Q101

H-PLS

I102

PWM

H-PLS

H OUTPUT

HOUT

CONTROLLER

FOCUS

DRIVER

CONTROL

Q416

DRIVER

850V

FOCUS

DYNAMIC

AMPLIFIER

HOT

VDEF

15V

T804

12V

POWER

I801

6.3V

TRANS

PWM

CONTROL

80V

180V

H- H+

D.Y

V-

V+

POWER SUPPLY

I301

VERT.

BOOST

TDA8351

P502

DIODE

BRIDGE

I701

NT68P61

KEY

S702

SCAN

LED

LD701

MAIN BOARD

MICRO CONTROLLER

Page 24 Block Diagram

INDICATION

P702

DDC-SCL

DDC-SDA

I702

I704

I703

DDC

PROM

DEG CKT

LINE

FILTER

Page 27

AC INPUT

Page 28

Page 29

Page 30

Page 31

Page 32

Page 33

LITE-ON TECHNOLOGY CORP. 5 F, No. 16, Sec. 4, Nanking E. Road, Taipei, Taiwan T el: 886-2-25706999 Fax: 886-2-25706888 URL:// www.liteontc.com

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