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Service Manual
19-inch Color Monitor
A1996NST
Service Manual Versions and Revision
No. Ve rs io n R e le a s e D a t e R e v is io n
1. 1 .0 D ec 3, 1997 O rigina l re le a se
2. 1 .1 O c t. 3 0 , 1 9 9 8 8 -1 (b )
3. 1 .2 A p ril 3 0, 1 9 9 9 2 -1
P o w e r In p u t- 1 2 0 W ( T O S H IB A C R T )
P o w e r In p u t- 1 3 0 W ( S A M S U N G C R T )
Copyright Trademarks
Copyright 1998 LiteOn Technology Corp. LiteOn is a registered trademark of LiteOn
Technology Corp.
All Rights Reserved
All other trademarks are the property of their
This manual may not, in whole or in part, be
respective owners.
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 Taiwan.
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
Troubleshooting Page 1
A1996NST
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 nonmetallic control knobs, insulating materials,
cabinet backs, adjustment and compartment
covers or shields, isolation resistor-capacitor
1-1-1 Warnings networks, mechanical insulators, etc.
1. For safety purpose, do not attempt to modify 3. AC Leakage Current Check
the circuit board, and always disconnect the AC Always perform the AC Leakage Current
power before performing servicing on the Check on the exposed metal parts, including
monitor. metal cabinets, screwheads and control shafts,
2. Operation of the monitor outside its cabinet or as follows:
with the cover removed involves the risk of a) Plug the AC line cord directly into a rated
shock hazard. Repair work on the monitor AC outlet. Do not use an isolation
should only be attempted by service personnel transformer during the check.
who are thoroughly familiar with all necessary
b) Use an AC voltmeter with at least 5000
safety precautions and procedures for working
ohms per volt sensitivity as follows:
on high voltage equipment.
Connect a 1500 ohms, 10 watt resistor
3. Do not lift the CRT by the neck. After
paralleled by a 0.15uF AC capacitor in series
completely discharging the high voltage anode,
with all exposed metal cabinet parts and a
handle the CRT only when wearing shatterproof
known earth ground, such as electrical
goggles. Try to keep the CRT away from the
conduct or electrical ground connected to
body during handling.
earth ground, as shown in the Figure 1-1.
4. High voltage should always be kept at the rated Measure the AC voltage across the
value, no higher. Only when high voltage is combination of resistor and capacitor.
excessive are X-rays capable of penetrating the
shell of the CRT. Operation at high voltages Figure 1-1. Set Up For AC Leakage Current Check
may also cause failure of the CRT or high
voltage circuitry.
5. The CRT is especially constructed to limit X-
ray emission to 0.5mR/HR at 300 microamperes
anode current. To ensure continued X-ray
protection, replace the CRT with only the same To kn ow n To ex pos ed m e tal
ca bin et part
or equivalent type as the original, and adjust the earth g ro und
0.15 ufd
anode's voltage to the designated maximum
rating, never to exceed.
15 00 o hm 1 0 w att
1-1-2 Safety Checks
Before returning the monitor to the user, perform
c) Reverse the AC plug at the AC outlet and
the following safety checks:
repeat the steps for AC voltage
1. Inspect to make certain that each lead dress is measurements for each exposed metal part.
not pinched or that hardware is not lodged
d) Voltage reading must not exceed 0.3 volts
between the chassis and other metal parts in
RMS, equivalent to 0.2 milliampere AC. Any
the monitor.
value exceeding this limit ill constitute a
2. Inspect all protective devices such as potential shock hazard and must be
corrected immediately.
Page 2 Precautions
A1996NST
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 Page 3
A1996NST
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.
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.
Page 4 Precautions
A1996NST
2 Product Specifications
2-1 Specifications
Picture Tube 19-inch (18-inch Visual image area), 90 degrees deflection, dot type black
matrix, medium short persistence phosphor, dark bulb,direct etch, Flat
square screen with Invar Mask,
0.26 mm dot pitch
VGA, Super VGA, 1024x768@60/70/75/85 Hz, 1280x1024@60/75/85 Hz,
Scanning Frequency
1600x1200@60/75 Hz
Maximum Resolution 1600 dots (H) x 1200 lines (V) @75 Hz refresh rate
Display Area 350