LITE-ON B1570MNS Service Manual

Service Manual

15-inch Color Monitor
B1570MNSL/T

Service Manual Versions and Revision

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

1. 1.0 June 27, 2000 Original relea se

B1570MNSL/T

Copyright

Copyright 2000 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
T echnology Corp.

B1570MNSL/T Service Manual.

T rademarks

LiteOn is a registered trademark of LiteOn
T echnology Corp.

All other trademarks are the property of their
respective owners.

Printed in Taiwan.

Page 28 Block Diagram

B1570MNSL/T

Table of Contents

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

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

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

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

5. Troubleshooting...............................................................................................19

6. Recommended Spare Parts List.......................................................................25

7. Block Diagram.................................................................................................27

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

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

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

Page 1

B1570MNSL/T

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

To kn o 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.

PrecautionsPage 2

B1570MNSL/T

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.

B1570MNSL/T

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 degrees

Picture Tube

Scanning Frequency VGA, Super VGA, 1024x768@60/70/75/85 Hz
Maximum Resolution 1280 dots (H) x 1024 lines (V) @60Hz refresh rate
Display Area 262 mm (H) x 196 mm (V) typi cal
Display Char acters 80 char. x 60 row s on a 10 x 10 matri x

deflection, dot type blac k matri x, medium short persistence

phosphor, dark tint, non-glare/ anti- static screen, mini-neck gun

0.28 mm dot pitch

B1570MNSL/T

Display Colors Analog
Input

Sync hroni zati n Signal s Se par ate Sync : hor izo ntal /ver tic al , TTL, pos iti ve o r nega tiv e
Sync hroni zati on

Frequencies
Signal Connectors 15-pin, D-shell connector
Video Signals Anal og : 0.7 Vp-p, RGB positive
Power Input 70 Watts (maximum) AC rated voltage, 100VAC to 240VAC
Misconvergence Center Area : <
Use r Cont rol s Pow er On/ Off, Contras t, Br ightne ss, Hor izo ntal S ize ,

Service Controls PWB-1484 : R-bias (VR910), G-bi as (VR940), B-bia s (VR970)

Unl imi ted Co lo r s

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

0.3 mm; Corner Ar ea : < 0.4mm

Horizontal Positi on, Vertical Size, Vertical Position,
Pi ncus hio n, Tra pe zo id , Ro tati on, Col or tempe ra ture , Langua ge,
Di spla y Fr eque ncy, De gaus s, R eca ll , H. Moi re ,
V. M o i r e

PWB- 1486 : power voltage adjust (VR801), high voltage adjust

(VR802), focus, ABL adj ust (VR401)
Preset Modes 10 (see Table 2-2. Ti ming Chart)
Enviro nmental

Considerations

Operation temperature : 10

Operation Humidity : 20% to 90% ambient

Storage temperature : -40oC to 65oC ambient

Storage Humidity : 10% to 90% (non-condensing)

Altitude : up to 10000m above sea level

o

C to 35oC 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 Assignment

Pin Signal Pin Signal

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

4 Gr o und 12 SDA
5* NC 13 H-Sync
6 Re d ground 14 V-Sync /VCL
7 Gree n ground 15 SCL
8 Bl ue gr ound

B1570MNSL/T

Note * This pin is used for selftest detection. Connect this pin to ground at the PC end.
** For PC 99: This pin will provide +5V from PC side.

Product SpecificationsPage 6

B1570MNSL/T

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 12345678910

H. Dots

V. D ots

H-freq (kHz)

Sync
Polarity

A period us

B Blking us

C Sync us

D B.P. us

E Active us

F F.P. us

V-freq (Hz)

Sync
Polarity

O Period ms

P Blking ms

720 640 800 640 640 800 1024 800 1024 1024

400 480 600 480 480 600 768 600 768 768

31.47 31.47 37.88 37.5 43.3 46.8 48.36 53.67 60.02 68.68

--+ - -+++++

31.78 31.78 26.4 26 .666 23.111 21.333 20.68 18.63 16 .66 14.56

6.356 6.356 6.4 6.35 5.33 5.172 4.923 4.409 3.657 3.725

3.81 3.81 3.2 2.07 1.556 1.616 2.092 1.138 1.219 1.016

1.907 1.907 2.2 3.81 2.222 3.232 2.462 2.702 2.235 2.201

25.42 25.42 20 20.32 17.778 16.162 15.75 14.22 13 10.836

0.636 0.636 1 0.51 1.556 0.323 0.369 0.569 0.203 0.508

70.08 59.95 60.32 75 85 75 60 85 75.03 85

+-+ - -+++++

14.27 16.68 16.58 13.33 11.764 13.333 16.67 11.76 13.33 11.77

1.557 1.43 0.739 0.533 0.67 0.533 0.786 0.578 0.533 0.582

Q Sync ms

R B.P. us

S Active us

T F.P. us

0.064 0.064 0.106 0.08 0.069 0.06 4 0.124 0.056 0.05 0.044

1.08 1.02 0.607 0.40 7 0.578 0.44 8 0.6 0.503 0.466 0.524

12.71 15.25 15.84 12.8 11.093 12.8 15.88 11.18 12.8 11.18

0.413 0.35 0.026 0.026 0.023 0.021 0.062 0.019 0.017 0.015

Horizontal

C

E

Video

D

Sync

A

B

F

H.Parameters:

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

Seperate Sync

Ver tic a l

V.Parameters:

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

K

Video

J

Sync

I

G

H

L

Product Specifications

Page 7

B1570MNSL/T

2-4 Display Power Management Signal (DPMS)

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

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

Table 2-3. Display Power Management Signal (DPMS)

State LED Color H-Sync V-Sync Power

Co nsumpt io n

ON Gre en Puls e Pul se Nor mal

STANDBY Yellow No Pulse Pulse <15 watts

SUSPEND Yellow Pulse No Pulse <15 watts

OFF Amber No Pulse No Pulse <5 watts

2-5 TCO V ersion (Optional)

The monitor meets the TCO 95/99, NUTEK energy saving, electric and magnetic field requirements. Also
it is compliant with TCO 95/TCO 99 labelling scheme.

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.

Table 2-4. TCO 95 Emission Requirements

OCT/FLVOCT/FLE

dleiFcitengaMTn52Tn002

dleiFcirtcelEm/V1m/V01

egnaRycneuqerFzHk004~2zH0002~5

eulaVSMRSMR

ecnatsiDmc03mc03

citatsortcelE

laitnetoP

V005-/+V005-/+

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

Product SpecificationsPage 8

B1570MNSL/T

2-5-1TCO 95 V ersion (Optional)

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 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.

T able 2-5. TCO 95 Visual Ergonomics

erutaeFdradnatSnoitpircseD

ytiraeniLsselro%1 ehtotderapmocsworrosnmulocfohtgnelniecnereffiD

.rotinomehtforetnecehthguorhtshtgnelgnidnopserroc

ecnanimuLyalpsiD)tsaelta(2m/dc001

ecnanimuL
ytimrofinU

sselro1:7.1 ehtnihtiwecnanimulnimotxamehtneewtebsioitarehT

.aeraevitcaelohw

2-5-2TCO 99 V ersion (Optional)

TCO 99 will append the color temperature and energy efficiency specification, also cover the environmental
requirement.

Product Specifications

Page 9

B1570MNSL/T

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. The NOVA TEK 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.

2

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

2

C Bus for auto-alignment through

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

3. Stores up to 10 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 TDA4866 and TDA4856 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 > = 70 kHz.

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

3-2 Microcontrol Section

1. This monitor uses NOV ATEK 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, 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 allowed 10 factory preset modes and 8 user modes. There are 11 functions, Contrast, Brightness, H.
Size, H. Position, V. Size, V. Position, Pincushion, and Trapezoid, Rotation, H. Moire, V Moire, all
controlled by OSD icon which can be adjusted by user.

3. The pin 25 and pin 26 are used for ATE function. When CPU receives C6 as slave address, it will operate
in ATE mode which is used for auto-alignment. After alignment the data will be stored in I703.

4. The user control parameters are selected by OSD icons, through

& 2 keys, they are detected by

1

sensing the voltage through R710, R740, R741, R743, R711, R742 to pin 14 and 15 of I701.

3-3 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.

Page 10 Operation Theory

2

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

B1570MNSL/T

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 goes into pin 15 through R318. And horizontal flyback pulse goes into pin 1 through R401

and bypass filter C403 from pin 6 of FBT and R4C2, R4C3 for HFLB loop.

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

3-3-2V ertical Section

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

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

3-3-3Vertical 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 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/Trapezoid 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 TDA4856.
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

3-3-5X-Ray Protection

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

by R403, R404 and R405 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 DR V (pin 6), VOUT1 (pin 12), VOUT2 (pin13). After that all deflection circuit stop working.

3-3-6G1, 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 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

B1570MNSL/T

2. Beam current is detected through T402 (FBT) pin 7, C429, R460, D406 and detected voltage feeding into
VR401, D430, Q409, R527, R528, R524, C571 to control I501 pin 24 voltage. When I501 pin 24 voltage
drops below 5V, the ABL function will happen.

3-3-8H/V size breathing compensation

1. Beam current is sensed as above section (4-3-7 item 2) and this voltage routes through R436, Q409, R459
then through R418 to I401 pin 31 for H. size compensation, through R302 to I401 pin 21 for V size
compensation.

3-3-9Dynamic focus circuitry

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 C413 through R4F2, C450, T401, R4F2, C433 and feed to
FBT dynamic focus pin.

3-4 Power Supply Section

3-4-1 AC Rectifier

The circuit can accept 90 V to 264 V AC input through D828~D831 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 C859, C860, C803, C816, C848, 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
states. It is controlled by CPU.

2. Normal : Green light
Amber LED is off because CPU pin 35 is 1.96V and pin 36 is 0.45V, only green LED is turned on.

3. Standby / Suspend : Y ellow light
CPU pin 36 is 1.87V and pin 35 is 1.96V, then green and amber LED are turned on. That is yellow.

4. Off Mode : Amber light
CPU pin 36 is 1.87V and pin 35 is 0.46V, then green is off and amber is illuminated.

3-4-4Auto Degaussing

When S801 turns on, pin 20 of I701 will send a signal to Q802 and turns on RL801 for degaussing. After 4
seconds, it will turn off RL801 automatically.

3-4-5PWM Control

1. Start Up

Page 12 Operation Theory

B1570MNSL/T

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 Synchronization

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 L81 1, D813, C824 and the gate control of Q807 comes
from I401 pin 6 via Q808, Q809, D821 and R849. The duty cycle is controlled by C843, C844, C846,
R846 and R856, R857, R858and 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 IC501 TDA 4886 preamplifier.

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

comes from pin 16 of TDA4856 to set up equal clamp level.

Operation Theory Page 13

2

C bus from I501, pin 5 is for clamp pulse which

B1570MNSL/T

3. The video output stages are amplified by I901 (LM2439).

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

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

3-6 OSD (On Screen Display) Circuit

1. The I502 HTV021-21 is OSD IC. The OSD signals are worked by positive vertical pulse from I701 pin 33
that goes through R517 to I502 pin 10, and positive horizontal pulse from T402 pin 6 goes through R4C2,
R4C3 to I502 pin 5. CPU I701 pin 28, 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, 14, 13, and 12 to I501 pin 2,
3,4, and 1, then the OSD picture appears.

Page 14 Operation Theory

B1570MNSL/T

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 Time

The monitor must be powered on for 15 minutes before starting any alignment, but requires 30 minutes of
warm-up time for convergence adjustment.

c) Signal Input

1. Video: RGB Analog, 0.7 Vp-p, positive

2. Synchronization: Horizontal and vertical TTL signal, separate, positive or negative

3. All adjustments should be made using a signal of FH = 68.68 kHz, FV = 85 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 (1024 x 768 @ 68.68 kHz/85 Hz) signal to the monitor.

3. Connect a DC voltage meter to TP001 (on the Main board), and adjust VR801 for 12.3 ± 0.1 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 P702 and P701 Jumper to short COM and A TE pins at power
off condition.

2. Press both

3. After turn the power off, this monitor will go back to normal mode.

4. When finish the normal alignment. Open A TE pin and change GND wire to GND1, put P701 and P702
jumper to short COM and DDC pins.

Alignments and Adjustments

key and 2 key simultaneously then power ON.

1

Page 15

B1570MNSL/T

4-2 Alignment Procedures

4-2-1High V oltage Adjustment

CONDITION

Display image : Crosshatch pattern

PROCEDURE

Connect DC meter to TP002 and adjust VR802 to obtain a DC voltage of -146.5 ± 0.15V DC for CPT CR T
M36AJA73X46 (TCO) or M36AJA83X46 (MPRII) or M36LEG128X (TCO) for TOSHIBA CRT.

4-2-2 Screen and White Balance Adjustment
CONDITION (Short ATE pin and short P701 and P702 jumper to ATE)
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 (68.68 KHz Mode)
1-a. Set brightness (OSD Icon) to -30 V at G1 and 640 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

2 6500

0

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=45±1.5FL
2-e Check x=313±5, y=329±5.
3 9300

0

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=298±5, x=283±5.

2

3-d Adjust Contrast to set Y=45±1.5FL
3-e Check x=283±5, y=298±5.

Page 16 Alignments and Adjustments

4 Full white ABL setting

CONDITION

Display image : full white pattern
4-a Set Brightness to cutoff and Contrast to maximum.
4-b. Adjust VR 401 to Y=30FL ± 1FL.
4-c. Check the white balance at 5FL and 28FL.
4-d. Repeat all the procedures in 4-2-2 section until the best white balance is obtained.

4-2-3Focus 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.

B1570MNSL/T

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
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.

Figure 4-1. Convergence Magnets on the CRT

1

11

+

P

CRT

FRONT

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

5) Spacer 7) Spacer

9) Holder

Alignments and Adjustments

6) 4-Pole Magnet

8 7 6 5 4 3 2

10

9

8) 6-Pole Magnet

11) Tabs10) Band

Page 17

B1570MNSL/T

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 Red

Bl u e Gree n

Blue
Red

4-pole magnets
movem e nt

Red/
Blue

Green

6-pole magnets
movem e nt

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 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.

4-2-6Manual 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.

Page 18 Alignments and Adjustments

5 T roubleshooting

5-1 No Raster

B1570MNSL/T

No Raster

Measure

voltage of B+ at

T402 pin 3 on

PWB-MAIN

Yes

Check DC

B+ line, Q808,

Q809, Q402,

Q807, T402

0 V

Short Circuit

at load?

No

Check AC I/P

on C808

NO

Check

I801, Q803,
R814, R813,
R818, R811,

ZD807, ZD801

Grid 1, Grid 2, etc.

YES

Check D828,

D829, D830,
D831, T801,

R891, F801

Normal

(68 V, 31.5 kHz)

Check voltage of

cathode, heater,

High

(75 V or more)

Check I401,
R858, R857,

R856, VR802

T roubleshooting

Page 19

5-2 OSD Abnormal

B1570MNSL/T

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

Yes

Replace I502

Page 20 T roubleshooting

5-3 Function Key Abnormal

Function Key Abnormal

B1570MNSL/T

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

T roubleshooting

Replace I701 and check

uP OK?

No

Check

pin 5 of I701

is 5V?

No

Replace R842, Q805

Yes

Yes

Replace I701

Check

pin 4 of I701

Page 21

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

No Vertical Scan

B1570MNSL/T

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,

R310, R311

Replace I401

Still no vertical scan

Check or replace CRT

Page 22 T roubleshooting

5-5 Out of Horizontal Synchronization

Out of Horizontal

Synchronization

B1570MNSL/T

Horizontal

sync present at

pin 15 of I401

Yes

Check

I401 pin 8 H. output

frequency & pin 29

waveform

Yes

Check Q401,

T401, Q402,
R424, D401

5-6 Out of Vertical Synchronization

No

No

Ckeck or replace

the signal cable or

H. sync pin 41

of I701.

Check or replace

I401, C406

Out of Vorizontal

Synchronization

Vorizontal

sync present at

pin 14 of I401

Yes

Check

I401 pin 24 waveform

Yes

Check I401 pin 13 & pin 14.

No

No

Ckeck signal cable

& V. sync pin 42

of I701.

Check or replace

C303, I401,

T roubleshooting

Page 23

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

RGB Video AMP Abnormal

B1570MNSL/T

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

(DC restore)

Page 24 T roubleshooting

B1570MNSL/T

6 Recommended Parts List

Note:1 . The components identified by “ “ mark are critical for X-ray safety. Replace these with

exactly the same parts specified.

2 . There is only OTP IC at the model beginning (FPR stage or before). When it put in mass

production and there must be Mask coming out. If you have spart parts need, please use BOM
to get the last release part number and related information.

No. Location Part Numbe r Description

1 Q401 6421002705 TR NPN KSD1616A G TA
2 C808 6312615102 ALU uF 150 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 50 nS
7 F801 6851504053 FUSE TIME LAG H-BRK 4A/250V
8 I301 6442012300 IC TDA4866 9P (PHILIPS)

9 I401 6442025200 IC TDA4856 32P SDIP (PHILIPS)
10 I501 6442021500 IC TDA4886 24P SDIP (PHILIPS)
11 I701 6448014500 IC NT68P61A 40P PDIP OTP NOVAT
12 I703 6448007930 IC 24C04A/P (MICROCHIP)
13 I704 6448007430 IC 24LC211/P 8P PDIP EEPROM
14 I801 6442022010 IC KA3842AC 8P PDIP SAMSUNG
15 L404 6111504130 COIL CHOKE 5mH K DR10x16 LY 3B

D828 D829
D830 D831

6412010907 DIODE LT2A06 T52 2A/800V

16 L405 6119006600 COIL LINEAR
17 L406 6111806131 COIL CHOKE 80uH DRWW 1 0x16 LY3B
18 L409 6111165131 COIL CHOKR L=105uH K DRWW 16x18
19 Q402 6421003200 TR NPN 2SC5339 (TOSHIBA)
20 Q418 6422002925 TR NPN HBF422T/B TO-92 TAPING
21 Q419 6422006000 TR NPN 2SD2012 TO-220(IS)

22

Q420 Q421
Q430

6426006400 FET N-CHNL IRFS630A SAMSUNG

Recommended Spare Parts List

Page 25

B1570MNSL/T

No. Location Part Number Description

23 Q803 6426006700 FET N- CHNL SSS 7N60 A SAMSUNG
24 Q807 6426006300 FET N-CHNL IRFS634A SAMSUNG
25 R803 6203080017 POSISTOR & OHM DGC2R08M
26 R804 6201160011 THERMISTOR 16 OHM 2A P=5 UEI
27 R818 6220322852 FS OHM 0.22 1W J HOR
28 R852 6221233852 MOF OHM 0.33 2W J HOR
29 T401 6135000801 XFRMER HOR DRIVE THD- 1008A EI19
30 T402 6133070150 FBT TFB-7015 FEA953 SAMPO (MPRII)
31 T403 6136001200 (CPT) XFRMER DYNAMIC TDF-1012 EI19LSE
32 T801 6138001601 LINE FILTER TLF-1016A 16mHET28
33 T802 6131051420 XFRMER PWR TPW-1062 EI40 LSE
34 X701 6449000700 CRYSTAL HC49/U 8MHZ 50ppm 7PF
35 T402 6133070151 FBT TFB-7015A FEA953A ( TCO)

36 T403

6136001000
(TOS HIBA)

XFRMER DYNAMIC TDF-1010 EI19

Page 26 Recommended Spare Parts List

7 Block Diagram

SDA

SCL

P501

Q901

R BUFFER &

DC RESTORE

Q931

G BUFFER &

DC RESTORE

Q961

B BUFFER &

DC RESTORE

BLANKING

CKT

I401

TDA4856

I501

R

G

B

12V

I701

NT68P61A

OSD

MTV021

ABL

I901

Video AMP

LM 2439

12V

SDA 1

SCL 1

V

H

RG

R

GG

G

BG

B

H

V

5V

SG

O/R

P701

P702

LED

DDC
I704

OSD
BLK

KEY

CONTROL

S702

R

G

B

PRE AMP

TAD4886

RGB

O/R

V

H
SDA
SCL

G

G1

ABL

BRIGHTNESS
CONTROL &
SPOT KILLER

H

DRIVER

SCL1

R

B

SDA1

C-LBL

R844

V-TTL

H

OUT

H-FLB

GND

5V

6.3V

12V

80V

145V

GND

P503

24.5KV

HFLB

-130V

650V

FBT

6.6KV
145V

DIODE

MODULATE

40V

RESET

CKT

E2PROM

I703

LINE

FILTER

BRIGHTNESS

DEG
CKT

BRIDGE

DIODE

5V

Q805

LOW VOLTAGE

DROP DOWN

SMPS

POWER

O/P

TRANS

T802

VERTICAL

O/P

I301

STEP

UP

CKT

TDA4866

XRP

12.5V

Q813

Q811

80V

dynamic

foucus

650V

+H

-H

+V

D.Y

-V

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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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