LITE-ON A1570 Service Manual

Service Manual

Color Monitor
A1570NSL/NST

Service Manual Versions and Revision

No. Vers ion Release Date Revision

1. 1.0 Sept. 8, 1998 Original release

Copyright

Copyright 1998 LiteOn T echnology Corp.
All Rights Reserved
This manual may not, in whole or in part, be

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

A1570NSL/NST 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.

A1570NSL/NST

Table of Contents

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

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

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

4. Alignments and Adjustments ........................................................................... 15

5. Troubleshooting............................................................................................... 20

6. Recommended Spare Parts List....................................................................... 26

7. Block Diagram ................................................................................................ 28

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

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

11. Schematic Diagrams ................................................................................ Inserted

Page 1

A1570NSL/NST

g

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 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

A1570NSL/NST

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.

Precautions

Page 3

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.

A1570NSL/NST

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

2 Product Specifications

2-1 Specifications

15-inch (13.8-inch Visual image area), sloted mask, 90

Picture Tube

degrees deflection, dot type black matrix, medium short

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

0.28 mm dot pi tch

A1570NSL/NST

Sc anning F req uency

Maximum Resolution 1280 dots (H) x 1024 li nes (V) @60Hz refresh rate
Display Area 262 mm (H) x 196 mm (V) typical
Display Characters 80 char. x 60 rows on a 10 x 10 matrix
Display Colors Analog

Input
Sync hroni zati n Signa ls Se par ate Sync: hori zonta l/vertic al, TT L, p osi tive or nega tive
Sync hroni zati on

Fr eque ncies
Si gnal Conne ctor s 15 -pi n, D- shel l connector
Video Si gnals Anal og : 0.7 Vp-p, RGB positi ve
Power Input 100 Watts (maximum) AC rated voltage, 100VAC to 240VAC
Misconvergence Center Area : <

Us er Control s

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

1280x1024@60 Hz

Unlimited Colors

Horizontal : 30 to 69 kHz
Vertical : 55 to 120 Hz

0.3 mm; Corner Area : < 0.4mm

Power On/Off, Cont ras t, Br ightne ss, Horizonta l Si ze,
Horizontal Position, Vertical Size, Vertical Position,
Pincushion, Trapezoid, Rotation, Color temperature,
Langua ge, Di spl ay Freque ncy, Dega uss, Recall, H. Moire,
V. M o i r e

Service Controls PWB-1439 : R-bias (VR910), G-bias (VR940),

B-bias (VR970),
PWB-1394 : power voltage adjust (VR801),

high voltage adjust (VR802), focus
Preset Modes 13 (see Table 2-2. Timing Chart)
Envir onmental

Considerations

Operation temperature : 10
Operation Humidity : 10% to 90% ambient
Storage temperature : -40
Storage Humidity : 20% to 80% (non-condensing)

Altitude : up to 7000ft above sea level

o

C to 3 5oC ambient

o

C to 6 5oC ambient

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

Product Specifications

Page 5

2-2 Signal Cable Pin Connections

Table 2-1. Signal Cable Pin Assignments

Pin S ignal Pin Signal

1Red video 9 NC

2 Gr een vid eo 1 0 Digita l Gr ou nd
3 Blue vide o 11 Gro und

4 Gr ound 12 SDA
5* NC 13 H-Sync
6 Re d gro und 14 V- S ync /VC L

7 Gr ee n gr ound 15 SC L

A1570NSL/NST

8Blue ground

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

Product SpecificationsPage 6

A1570NSL/NST

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 11 12 13

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

V. D o t s

H-freq (kHz) 3 1. 47 31.47 35 37. 88 37. 5 43. 3 46.8 48.36 53. 67 56.48 60.02 64.34 68.68

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

A pe riod us 31.78 31.78 28.57 26.4 2 6.66 6 23.111 21.33 3 2 0.68 1 8.63 17.71 16.66 15.55 14.56

B Blking us 6.356 6.356 7.407 6.4 6.35 5.33 5.172 4.923 4.409 4.053 3.657 3.589 3.725

C S ync us 3.81 3.81 2.116 3.2 2.07 1.556 1.616 2.092 1.138 1.813 1.219 0.972 1.016

D B.P. us 1.907 1.907 3.175 2.2 3.81 2.222 3.232 2.462 2.702 1.92 2.235 2.248 2.201

E Acti ve us

F F. P. us 0.636 0.636 2.116 1 0.51 1.556 0.323 0.369 0.569 0.32 0.203 0.374 0.508

V-freq (Hz) 70.08 59.95 66.667 60.32 75 85 75 60 85 70.07 75.03 60 85

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

O Period ms 14.27 16. 68 15 16.58 1 3.33 11.76 4 13. 333 16.67 11.76 14.27 13.33 16.67 11.77

P B lking ms 1.557 1.43 1.286 0.739 0.533 0.67 0.533 0.786 0.578 0.673 0.533 0.642 0.582

Q Sy nc ms 0.064 0.064 0.086 0.106 0.08 0.069 0.064 0.124 0.056 0.106 0.05 0.047 0.044

400 480 480 6 00 480 480 600 768 600 768 768 102 4 768

25.42 25.42 21.164 20 20.32

17.77­8

16.162 15.75 14.22 13.65 13 11.96

10.83­6

R B.P. us 1.08 1.02 1.14 0.607 0.407 0.578 0.448 0.6 0.503 0.513 0.466 0.501 0.524

S Active us 12.71 15.25 1 3.714 15.84 1 2.8 11.093 12.8 15.88 11.18 13.6 12.8 16.03 11. 18

T F.P. us 0.413 0.35 0.086 0.026 0.026 0.023 0.021 0.062 0.019 0.053 0.017 0.094 0.015

Seperate Sync

H orizontal

C

E

Video

D

Sync

A

H.Parameters:

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

Product Specifications

Vertical

B

F

I

V.Parameters:

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

K

Video

J

Sync

G

H

L

Page 7

A1570NSL/NST

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 nsumptio n

ON Green Pulse Pulse Nor mal

STANDBY Yellow No Pulse Pulse <15 watts

SUSPEND Yellow Pulse No Pulse <15 watts

OFF Amber No Pulse No Pulse <5 watts

2-6 TCO Version (Optional)

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

2-6-1TCO 92 Version

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

A1570NSL/NST

2-6-2TCO 95 Version

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

Page 9

A1570NSL/NST

3 Operation Theory

This is a fully digital controlled multi-sync color monitor that is compliant with DDC1 and 2B Plug and Play
VESA standard and offers the following main features.

3-1 Main Features

1. Simplified design with minimum components.

2

2. The NOVATEK NT68P61A 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

2

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

C Bus for auto-alignment through

signal cable (g) CS1/CS2/CS3/CS4 for linearity and size compensation.

3. Stores up to 14 factory preset modes and offers 8 user modes. There are 16 function icons at OSD. They
are controlled by

2 keys on front panel.

1

4. Powerful PHILIPS TDA4854 and TDA4866 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 -- factory adjust, (k) X­ray protection, and (l) Full horizontal and vertical auto sync capability.

5. Software controlled auto shut off function activated if fH < = 29 kHz and fH > = 70 kHz.

6. Full range AC input and simplified line filter design.

3-2 Microcontrol Section

1. This monitor uses NOVATEK NT68P61 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,
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
39 and pin 40, 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 4854 and some DAC in CPU, above operation
takes about 500 ms.

2. There allowed 14 factory preset modes and 8 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 24 and pin 25 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

1

sensing the voltage through R710, R740, R741, R743, R709, R742 to pin 13 and 14 of I701.

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
controllable by I
control all functions.

Page 10 Operation Theory

2

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

A1570NSL/NST

3-3-1 Horizontal Section

1. The oscillator is driven by the currents in R419 and R420. The minimum oscillator frequency is determined

by R419 and the maximum frequency is determined by R420.

2. Horizontal sync comes into pin 15 through R318. And horizontal flyback pulse comes into pin 1 through

R401 and by pass filter C403 from pin 9 of FBT and C453, R4C2, Q414, R4C3 for HFLB loop.

3. Horizontal driver (pin8) O/P to Q401 via C410.

3-3-2 Vertical Section

1. V ertical sync comes into pin 14 through R317.

2. The free running frequency is determined by R301 and C301.

3-3-3 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 1 and pin 2 of TDA4866.

2. The TDA4866 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. This IC is powered by two sets of positive voltage. (+12V at pin 3, +42V at pin 7).

3-3-4 E-W/T rapezoid and H. Width Contr ols

1. The horizontal O/P stage uses diode modulator D419, D433, C411, C412, L409 and C418 for East-West

(Pincushion) Trapezoid and H. width controls.

+

2. The scan current is determined by B

accomplished by Darlington pair Q418 and Q419 by coupling a parabola waveform from pin 11 of TDA4854.
The H. width / corner and trapezoid correction are also accomplished by this pin 11. The DC level controls
H. size. The AC level is combined with side pin and trapezoid corners functions.

minus Vm ( the voltage of C418) values and the pincushion control is

3-3-5 X-Ray Protection

1. To avoid X-ray hazard, a DC voltage generated by pin 6 of FBT and rectified by D408, C432 and divided

by R403, R404 and R405 come into pin 2 of TDA4854.

2. If this voltage is higher than 6.39 V , then TDA4854 will be activated to float HUNLOCK (pin17), H. DRV

( pin 8), B DR V (pin 6), VOUT1 (pin 12), VOUT2 (pin13). After that all deflection circuit stop working.

3-3-6 G1, Blanking and Brightness

1. The vertical blanking signal comes from two ways. One is from pin 8 of I301 (TDA4866), the other is

from vertical sync (pin 32 of I701). These two positive vertical pulses through Q405 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 Q406 and to

cutoff Q407, then 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 1 through PNP transistor Q407. The lower control voltage causes

Q407 conducts darken to get lighter raster and a higher control voltage causes Q407 conducts lighter to get
lower brightness.

3-3-7 Contrast Section

1. Contrast is controlled by I701 through I2C bus to I501 (TDA4886) directly.

Operation Theory Page 11

A1570NSL/NST

2. Beam current is detected through T402 (FBT) pin 7, C429, VR401, R460, D406 and detected voltage
feeding into R455, R447, Q410, R527, R528, R524, C571 to control I501 pin 24 voltage. When I501 pin
24 voltage drops below 5V, the ABL function will happen.

3-3-8 H/V size breathing compensation

1. Beam current is sensed as above section (4-3-7 item 2) and this voltage routes through R456, C449,
Q409, R467, R457, R4A3, C436 then through R418 to I401 pin 31 for H. size compensation, through
R302 to I401 pin 21 for V size compensation.

3-3-9 Dynamic 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 Q4F1, Q4F2, Q4F3,
C4F4, T4F1, R4F8 and feed to FBT dynamic focus pins.

2. This amplifier need 58V voltage supply, it comes from T802 pin 1 1 and rectified through L810, D813 and
C824.

3-4 Power Supply Section

3-4-1 AC Rectifier

The circuit can accept 90 V to 264 V AC input through D801~D804 bridge diodes and C808 filtering to get
DC 126 V~364 V for power conversion in T802.

3-4-2 Line Filter

It consists of C801, C802, C803, C816, C839, C840, C852, C853, C807 and T801 and meets EMI
regulation.

3-4-3 Power LED Status

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

2. Normal : Green light
Amber LED is off because CPU pin 35 is high and pin 34 is low, only green LED is turned on.

3. Standby / Suspend : Y ellow light
CPU pin 34 and pin 35 are low, then green and amber LED are turned on. That is yellow.

4. Off Mode : Amber light
CPU pin 34 is high and pin 35 is low, then green is off and amber is illuminated.

3-4-4 Auto Degaussing

When S701 turns on, pin 19 of I701 will send a signal to Q802 and turns on RL801 for degaussing. After 4
seconds, it will turn off RL801 automatically.

Page 12 Operation Theory

A1570NSL/NST

3-4-5 PWM Control

1. Start Up

The I801 (MC3842) gets power from R807, 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 D808 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 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.

3-4-6 Sy nc hr onization

1. Normal Mode

The sync pulse from FBT (31 kHz~69 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 R815 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.

3-4-7 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.

3-4-8 O.P.P.

The excess current of T802 through Q803, R813 and R814 can develop enough voltage on pin 3 then limit the
power delivered because the pin 6 duty cycle is limited too.

3-4-9 Step Up Power Supply For FBT

1. The B+ of FBT is proportional to horizontal frequency, that is the higher frequency, the higher voltage.

The basic voltage is 58 volts from T802 pin 11 via L810, D813, C824 and the gate control of Q807 comes
from I401 pin 6 via Q808, Q809, D826 and R849. The duty cycle is controlled by C843, C844, C846,
R848 and R856, R857, R858, R873 and VR802 combination ratio.

2. The regulation and boost up (from 68 V to 160 V or more, on demand). The H.V. is set at 24.5 kV (zero

beam) by VR802 which senses the secondary O/P from FBT. The booster comprises Q807, L802, L801,
D820, C425 and T802 to offer the required B+ for different frequency modes.

3-5 Video Amplifier Section

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

C503, C533 and C563 to the IC501 TDA 4886 preamplifier.

Operation Theory Page 13

A1570NSL/NST

2. The amplifier RGB signals (0~3 Vpp) are adjusted by I2C bus from I501, pin 5 is for clamp pulse which
comes from pin 16 of TDA4854 to set up the equal clamp level.

3. The video output stages are amplified by I901 (LM2407).

4. The RGB cathodes cut off are adjusted by VR910, VR940 and VR970.

5. Under override condition, “NO SIGNAL” will show on the screen.

3-6 OSD (On Screen Display) Circuit

1. The I502 HTV018-08 is OSD IC. The OSD signals are worked by positive vertical pulse from I701 pin 32
that goes through R517 to I502 pin 10, and positive horizontal pulse from T402 pin 9 goes through C453,
R4C2, Q414, R4C3 to I502 pin 5. CPU I701 pin 26, 27 (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 to I501 pin 2,
3,4, and 1, then the OSD picture appears.

Page 14 Operation Theory

A1570NSL/NST

4 Alignments and Adjustments

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

4-1 General Adjustments

4-1-1 Adjustment 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 = 31.468 kHz, FV = 60 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 2000)

6. Screwdriver

4-1-3 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 VGA (640 x 480 @ 31.47 kHz/60 Hz) signal to the monitor.

3. Connect a DC voltage meter to TP005 (on the Main board), and adjust VR801 for 6.05 ± 0.05 Vdc

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. Change GND1 wire to ATE pin and put COM wire short COM and ATE 1 at power off condition.

2. Press both
Now, we are in the factory preset mode.

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

4. When finish the normal alignment. Open A TE pin and change GND wire to GND 1, put COM wire to
short COM and DDC.

Alignments and Adjustments

key and 2 key simultaneously then power on.

1

Page 15

A1570NSL/NST

4-2 Alignment Procedures

4-2-1 High V oltage Adjustment

CONDITION

Display image : Crosshatch pattern

PROCEDURE

Connect DC meter to TP002 and adjust VR802 to obtain a DC voltage of -145.7 ± 0.5V DC for CPT CRT
M36AJD85X46 or LG CR T M36LBL 803x801

4-2-2 Screen and White Balance Adjustment

CONDITION (Short ATE pin and short ATE1 pin)
Press

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

1

Bias VRs : VR910, VR940, VR970
Display image : No video

PROCEDURE

1 Raster color setting (31 KHz Mode)
1-a. Set brightness (OSD Icon) to -30 V at G1 and 600 V at G2.
1-b Adjust VR910, VR940 and VR970 to maximum.
1-c Adjust VR940 to y=0.9 ± 0.2 FL.
1-d Adjust VR910 to get x=280 ± 5 and VR970 to get y=280 ± 5
1-e Adjust brightness to raster just distinguish.

CONDITION

Display image : 50 mm x 50 mm white block pattern

PROCEDURE

0

2 6500

K color temperature setting
2-a. Set brightness to cutoff and contrast to maximum.
2-b Move cursor on OSD to choose color temperature icon.
2-c. Press

key to G gain then adjust G gain = 70 value, then adjust B, R to y=329±5, x=313±5.

2

2-d Adjust contrast to set y=40±5FL
2-e Check x=313±5, y=329±5.

0

3 9300

K color temperature setting
3-a. Set brightness to cutoff and contrast to maximum.
3-b Move cursor on OSD to choose color temperature icon.
3-c. Press

key to G gain then adjust G gain = 75 value, then adjust B, R to y=311±5, x=281±5.

2

3-d Adjust contrast to set y=40±5FL
3-e Check x=281±5, y=311±5.
4 Full white ABL setting

Page 16 Alignments and Adjustments

A1570NSL/NST

CONDITION

Display image : full white pattern
4-a Set brightness to cutoff and contrast to maximum.
4-b. Adjust VR 401 to y=28FL ±2FL.
4-c. Check the white balance at 5FL and 28FL.
4-d. Repeat all the procedures in 5-2-2 section until the best white balance is obtained, then power off.

4-2-3 Focus Adjustment

CONDITION

Display image : “e” character pattern

PROCEDURE

1. Set brightness to cutoff and contrast to maximum.

2. Adjust center VR at T402 (static focus VR) to make horizontal line clear.

3. Repeat above procedures to get best focus.

4-2-4 Dynamic focus Adjustments

1. Horizontal dynamic focus set Hf=300V in phase (compare with video signal). Test pin TP004.

2. Vertical dynamic focus set Vf=0 (OSD Icon Value).

4-2-5 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 of warm-up time for convergence adjustment.

CONDITION

Display image : Crosshatch pattern
W arm-up Time : 30 minutes

Alignments and Adjustments

Page 17

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

1

11

+

A1570NSL/NST

P

CRT

FRONT

8 7 6 5 4 3 2

10

9

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/
Blue Gree n

6-pole magn ets
movement

Blue
Red

Blue Red

Red/
Blue

Green

4-pole magn ets
movement

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

Page 18 Alignments and Adjustments

A1570NSL/NST

4-2-6 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.

4-2-7 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.

T roubleshooting

Page 19

5 T roubleshooting

g

p

,

,

,

,

(

)

(

)

,

,

,

, Q

,

,

,

Q

,

Q

5-1 No Raster

No Raster

Measure

volta

e of B+ at

T402

in 3 on

PWB-MAIN

A1570NSL/NST

0 V

Short Circuit

at load?

Yes

Check DC B+ line

808, Q809, Q402

807, T402

68 V, 31.5 kHz

Check voltage of

No

Check AC I/P on

I801

R814, R813, R818

R811, ZD807, ZD801

cathode

1

C808

Yes

Check

803

Normal

heater, Grid

Grid 2, etc.

No

D801

D804, T801, R804

High

75 V or more

Check I401, R858

R857, R856, VR802

R873

Check

D802, D803

F801

Page 20 T roubleshooting

5-2 OSD Abnormal

A1570NSL/NST

OSD Abnormal

Check I502 pin 9, 4 is
5V and pin 5, 10, 7, 8

missing?

No

Check R518,

R519, R520

OK?

Yes

Check P502

OK?

Yes

No

No

Put on

I502

Replace them

Replace it

T roubleshooting

Yes

Replace I502

Page 21

5-3 Function Key Abnormal

Function Key Abnormal

A1570NSL/NST

Check I701 and

I703 missing?

No

Power

ON/OFF again and

check X701,

oscillator OK?

Yes

Check

I703 EEPROM

content OK?

Yes

Yes

No

No

Put on

I701, I703

Replace X701

Replace I703 or

do ATE again

Replace I701 and

check uP OK?

No

Check

pin 5 of I701

is 5V?

No

Yes

Yes

Replace I701

Check

Q703, Q704

Replace R842, Q805

Page 22 T roubleshooting

5-4 No Vertical Scan (Raster is one horizontal line)

No Vertical Scan

A1570NSL/NST

Check I301 voltage of

pin 3 is 12V, pin 7

is 48V?

Yes

Check

pin 6 O/P waveform at

I301

Yes

Check

pin 1, 2, 9 of I301

waveform

No

No

No

Ckeck or replace

R309, I301, R308

Check R313, P301

Replace I401

T roubleshooting

Still no vertical scan

Check or replace CRT

Page 23

5-5 Out of Horizontal Synchronization

g

p

,

y

p

p

q

y

,

Out of Horizontal

S

nchronization

A1570NSL/NST

Horizontal

s

nc present at

in 15 of I401

Yes

Check

I401

in 8 H. output

fre

uency & pin 29

waveform

Yes

Check Q401, T401, Q402

R424, D401

5-6 Out of Vertical Synchronization

Out of Vertical

Synchronization

No

No

Ckeck or replace the

si

nal cable or H.

SYNC

in 39 of I701

Check or replace I401

C406

Vertical sync

present at

pin 14 of I401

Yes

Check

I401 pin 24 waveform

Yes

No

No

Ckeck signal cable &

vertical sync pin 40 of

I701

Check or replace

C301, I401

Check I401 pin 13 & pin 14

Page 24 T roubleshooting

5-7 R.G.B. Video Amplifier Abnormal

RGB Video AMP Abnormal

A1570NSL/NST

Check

waveform at I501 pin 16, 19

and 22

Yes

Check

I901 pin1, 3 & 5 collector

voltage (normally about 72V)

& waveform

Yes

Video signal present at the

pin of the CRT R.G.B.

Cathode

Yes

Check or replace the

No

signal cable or I501

No

Check I901

Defective cut-off circuit

Recommended Spare Parts List

(DC restore)

Page 25

A1570NSL/NST

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 Number De s cription

1 Q401 6421002705 TR NPN KSD1616A G TA

2 C 808 6312622126 ALU uF 220 400V F 85C 25x40

3

4 D814 6412017900 DIODE RL3 3.5A/350V SANKEN
5 D815 6412004117 DIODE UF2004M T52 2A/400V 50nS
6 D820 6412002017 DIODE UF3004M T52 3A/400V 50nS
7 F801 6851504050 FUSE TIME LAG H-BRK 4A/250V
8 I301 6442012300 IC TDA4866 9P (PHILIPS)
9 I401 6442020700 IC TDA4854 32P SDIP (PHILIPS)

10 I501 6442021500 IC TDA4886 24P SDIP (PHILIPS)

11 I701 6448012200 IC NT68P61A 40P PDIP OTP NOVAT
12 I703 6448007900 IC 24C04A/P (MICROCHIP)
13 I704 6448007430 IC 24LC211/P 8P PDIP EEPROM
14 I801 6442022000 IC KA3842AC 8P PDIP SAMSUNG

D801 D802
D803 D804

6412010907 DIODE LT2A06 T52 2A/800V

15 L404 6111504130 C OIL CHO KE 5mH K DR10x16 LY3B
16 L405 6119005600 COIL LINEAR
17 L406 6111286131 C OIL CHOKE 28uH DRWW10x16 LY3B
18 L409 6111105131 C OIL CHO KE L=105uH K DRWW16x18
19 Q 402 6421004400 TR NPN 2SC5386 (TOSHIBA)
20 Q418 6422002925 TR NPN HBF422T/B TO- 92 TAPING
21 Q 419 6422006000 TR NPN 2SD2012 TO-220(IS)

22

23 Q4F2 6424002900 TR PN P 2SB649AC TO- 126(HITACHI)

Q420 Q421
Q430

6426006400 FET N -C HNL IRFS630A SAMSUNG

Page 26 T roubleshooting

A1570NSL/NST

No. Locat ion Part Numbe r Des cription

24 Q4F3 6422006200 TR NPN 2SD669AC TO-126( HITACHI)

25 Q803 6426006800 FET N-CHNL SSS10N60A SAMSUNG

26 Q807 6426006300 FET N-CHNL IRFS634A SAMSUNG

27 R803 6203080017 POSISTOR 8 OHM DGC2R08M

28 R804 6201160011 THERMISTOR 16 OHM 2A P=5 UEI

29 R818 6221127852 MOF OHM 0.27 1W J HOR

30 R852 6221233852 MOF OHM 0.33 2W J HOR

31 T401 6135000801 XFRMR HOR DRIVE THD-1008A EI19

32 T402 6133070040 FBT TFB- 7004 FEA788 SAMPO

33 T4F1 6136000910 XFRMR DYNAMIC TDF-1009 EI19LSE

34 T801 6138001601 LINE FILTER TLF-1016A 16mHET28

35 T802 6131051410 XFRMER PWR TPW-1062 EI40 AXIS

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

Block Diagram

Page 27

7 Block Diagram

P501

GND

R

GND

G

GND

B

OSD
BLK

R

G

B

RGB

I501
PRE AMP
TDA4886

R

G

B

12V

I502

OSD

MTV018-08

Video AMP

ABL

I901

LM 2407

A1570NSL/NST

Q901
R BUFFER &
DC RESTORE

Q931
G BUFFER &
DC RESTORE

12V

Q961

B BUFFER &

DC RESTORE

GND

SDA

SCL

P502

G1

ABL

SCL1

SDA1

BRIGHTNESS

CONTROL &

SPOT KILLER

H

DRIVER

V+

Q806
Q810

O/P
I301

CLBL

H

V

5V

KEY

CONTROL

S702

RESET

CKT

SCL1

SDA1

O/R

V

H
SDA

SCL

I701

NT68P61A

E2PROM

I703

ATE

SDA 1

SCL 1

V

H

BRIGHTNESS

DEG
CKT

I401

TDA4854

5V

Q805

O/R

P501

LED

COM

ATE1

DDC

DDC
I704

P503A

BLANKING

CKT Q302

HFLB

TDA4866

VERTICAL

VTTL

H

OUT

HFLB

GND

5.1V

6.3V

12.5V

XRP

78V

GND

DIODE

MODULATE

148V

24.5KV

STEP UP

T402
FBT

CKT

Q807

-140V

600V

148V

+H

-H

+V

D.Y

-V

12.5V

Q813

LINE

FILTER

BRIDGE

DIODE

SMPS

LOW VOLTAGE

DROP DOWN

POWER

O/P

TRANS

T802

6.3V

7V

Q811

58V

78V

dynamic

58V

foucus

Page 28 Recommended Spare Parts List

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5 F, No. 16, Sec. 4, Nanking E. Road, Taipei, Taiwan
T el: 886-2-25706999 Fax: [phone]
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