R
Service Manual
19-inch Color Monitor
B1997PNST (MD 1998LE)
Service Manual Versions and Revision
No. Vers ion Release Date Revision
1. 1.0 Nov. 21, 2000 Original release
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
Technology Corp.
MD 1998LE (B1997PNST) 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.
MD 1998LE (B1997PNST)
Table of Contents
1. Precautions.........................................................................................................2
2. Product Specifications .......................................................................................5
3. Operation Theory................................................................................................9
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
Page 1
MD 1998LE (B1997PNST)
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 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 kno w n
earth ground
0.15ufd
1500 ohm 10 watt
To ex posed m e tal
cabinet part
c) Reverse the AC plug at the AC outlet and
repeat the steps for AC voltage
measurements for each exposed metal part.
d) Voltage reading must not exceed 0.3 volts
RMS, equivalent to 0.2 milliampere AC. Any
value exceeding this limit ill constitute a
potential shock hazard and must be
corrected immediately.
PrecautionsPage 2
MD 1998LE (B1997PNST)
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
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.
MD 1998LE (B1997PNST)
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
MD 1998LE (B1997PNST)
2 Product Specifications
2-1 Specifications
Picture Tube 19-inch (18- inch Visual image area), 95 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
Sc a nning Fr eq uenc y
Maximum Resolution 1600 dots (H) x 1200 lines (V) @75 Hz refresh rate
Disp la y Are a
Display Characters 80 char. x 60 rows on a 10 x 10 matrix
Disp la y Co lor s Ana log
Input
Sync hroniza tin Signa ls Se pa rat e S ync: hor izonta l/ver tic al, TTL, po sit ive or negat ive
Synchronization
Fr e que ncie s
Signal Connectors 15-pin, D- shell connector
Video Signa ls Analog : 0.7 Vp-p, RGB positive
Power Input
Misconvergence Center Area : <
VGA, Super VGA, 1024x768@60/70/75/85/100 Hz, 1280x960@85 Hz
1280x1024@60/75/85 Hz, 1600x1200@60/75 Hz
360 mm (H) x 270 mm (V) typical
Unlimite d C olo rs
Horizontal : 30 to 98 kHz
Vertical : 50 to 120 Hz
150 Watts maximum (PHILIPS CRT) AC rated voltage, 90VAC to 264VAC
0.2 mm; Corner Area : < 0.35 mm
Use r Co ntr ols
Service Controls PWB1498 : power voltage adjust (VR801), high voltage adjust (VR102),
Preset Modes 13 (see Table 2-2. Timing Chart)
Enviro nmenta l
Considerations
Power On/Off, Contrast, Brightness, Horizontal Size, Horizontal Position,
Vertical Size, Vertical Position, Pincushion, Trapezoid, Rotation, Unbalance,
Parallelogram, Degauss, Top Corner, Bottom Corner, Recall,
V. Moir e, H. Moir e
F1/F2/G2 (FBT)
o
Operation temperature : 10
Humidity : 20% to 80% ambient
Storage temperature : -40oC to 65oC ambient
Storage Humidity : 10% to 90% (non- condensing)
Altitude : up to3000m above sea le vel
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 (from PC)
2 Green video 10 Ground
3 Blue video 11 Ground
4 Gr o und 12 S DA
MD 1998LE (B1997PNST)
5*
6 Re d ground 14 V-Sync
7 Gr een ground 15 SCL
8 Bl ue gr ound
Note: This pin is used for selftest detection. Connect this pin to ground at the PC end.
NC
13 H-Sync
Product SpecificationsPage 6
MD 1998LE (B1997PNST)
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 12345678910111213
H. Dot s
V. D o t s
H-f req (kHz )
Sync
Polarity
A pe rio d us
B Bl king us
C Sy nc us
D B.P. us
E Active us
F F. P. us
V-freq (Hz)
Sync
Polarity
O Period ms
P Blking ms
640 7 20 640 800 1152 800 1 024 1024 1280 1280 1024 1600 1280
480 400 480 600 864 600 768 768 1024 1024 768 1200 960
31.47 37.93 43.27 46.8 67.5 53.67 60.03 68.67 80 91.146 80 93.75 85.938
---++++++++++
31.78 26.366 23.11 21.33 14.815 18.631 16.66 14.561 12.504 10.971 12.376 10.667 11.636
6.356 6.085 5.33 5.172 4.148 4.409 3.657 3.725 3.022 2.844 3.624 2.765 3.017
3.81 2.028 1.556 1.616 1.185 1.138 1.219 1.016 1.067 1.016 1.231 0.948 1.077
1.907 3.042 2.22 3.232 2.37 2.702 2.235 2.201 1.837 1.422 2.12 1.501 1.508
25.42 20.282 17.78 16.16 10.667 14.222 13 10.836 9.481 8.127 8.752 7.901 8.62
0.636 1.014 1.556 0.323 0.593 0.569 0.203 0.508 0.119 0.406 0.273 0.316 0.431
59.94 85.04 85 75 75 85 75.03 84.99 75 85 100 75 85
-+-++++++++++
16.68 11.759 11.76 13.33 13.333 11.756 13.33 11.765 13.329 11.761 9.988 13.333 11.764
1.43 1.213 0.67 0.533 0.533 0.578 0.533 0.582 0.525 0.527 0.483 0.533 0.593
Q Sync ms
R B.P. us
S Active us
T F.P. us
0.064 0.079 0.069 0.064 0.044 0.056 0.05 0.044 0.038 0.033 0.074 0.032 0.035
1.02 1.107 0.578 0.448 0.474 0.503 0.466 0.524 0.475 0.483 0.397 0.491 0.547
15.25 10.546 11.09 12.8 12.8 11.179 12.8 11.183 12.804 11.235 9.505 12.8 11.171
0.35 0.026 0.023 0.021 0.015 0.019 0.017 0.015 0.013 0.011 0.013 0.011 0.012
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
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