Samsung MA267 Series User manual

cB SAMSUNG
MA267*
MA467*

CONTENTS
• SPECIFICATION ................................................ " ........................ 2
• IMPORTANT SERVICE SAFETY PRECAUTIONS .......................................... 3 -4
• THEORY OF OPERATION ............................................................ 5 - 7
• DISASSEMBLY INSTRUCTION ............................................................ 8
• BLOCK DIAGRAM ...................................................... , ............... 9
• ALIGNMENT INSTRUCTION .......................................................... 10 -11
• SIGNAL TIMING CHART ................................................................. 12
• TROUBLESHOOTING GUIDE ......................................................... 13 -14
• WIRING DIAGRAM AND CIRCUIT BOARD DIAGRAM ...................................... 15 - 18
• WAVEFORM AND VOLTAGE .......................................................... 19 - 20
• EXPLODED VIEW ................................................................... 21 - 24
• EXPLODED VIEW PARTS LIST ........................................................ 25 - 28
• ELECTRICAL PARTS LIST ............................................................ 29 - 36
• SCHEMATIC DIAGRAM .............................................................. 37 - 38
• SEMICONDUCTOR LEAD IDENTIFICATION ................................................. 39
• MEMO

SPECIFICATION
DESCRIPTION NOMINAL
LIMIT
Power Input AC
12OV, 60Hz +/-10 %
AC 220V, 50Hz
+/-10%
AC 240V, 50Hz +/-10 %
Power Consumption 29 WATTS MAX 40 WATTS
Video Input Signal Separate TTL Signal 3.5Vp-p + /- 1.0 Vp-p
Video Bandwidth 20 MHz at -3 dB
Video displaySize 220 x150 mm ( MA267* )
230 x 170 mm ( MA467* )
Number of Characters 2000 Characters 80 Columnsx 25 Rows
Resolution 720 Dotsx 350 Lines
CRT
12/141nch Diagonal, Phosphor ( * )
90 Degress Deflection
1. White
Non-Glare 3. Green
Flat Square type 5. Amber
Synchronous
a) Horizontal 18.432 KHz
"
b) Vertical
50Hz
Dimensions MA267*
Width : 384 mm
Height: 324 mm
Depth : 372 mm
MA467*
Width : 386 mm
Height: 336 mm
Depth : 384 mm
Weight MA267* : 8.6 Kg
MA467* : 9.5 Kg
Note: Nominal specifications represents the design specifications ; all units should be able to approximate
these -some will exceed and some may
drop slightly below these specifications.
Limit specfications represents the absolute worst condition which still might be considered acceptable
; in no case should a unit perform to less than within any limit specification.
2

IMPORTANTSERVICE SAFETY PRECAUTIONS
Service w~rk should be performed only by qualified service technicians who are thoroughly familiar with all of
the following safety checks
and servicing guidelines:
WARNING
1. For continued safety,do not attempt to modify
the circuit.
2. Disconnect the AC power before servicing.
3. Semiconductor heat sinks are potential shock
hazards when the chassis
is operating.
SERVICING TEE HIGH VOLTAGE SYSTEM AND
PICTURE TUBE
When servicing the high voltage system, remove the
static charge by connecting a 10kohm resistor
in
series with an insulated wire(such as a test probe)
between the chassis and the anode
lead. (The AC
line cord should be disconnected from the AC outlet.)
1. The picture tube in this display monitor employs
integral implosion protection.
2. Replace with a tube of the same type and
number for continued safety.
3. Do not lift the picture tube by the neck.
4. Handle the picture tube only when wearing shat-
ter proof goggles and after discharging the high
voltage anode completely.
X-RADIATION AND HIGH VOLTAGE LIMITS
1. Be sure all service personnel are aware of the
procedures and instructions covering X-radia-
tion. The only potential source of X-ray in a
current solidstate display monitor
is the tube.
However,the
picture tube does not emit
measurable X-ray radiation if the high voltage
is
as specified in the "high voltage check" instruc-
tion.
It is only when high voltage is excessive that
X-radiation
is capable of penetrating the shell of
the picture tube,including the lead
in glass
material.
The important precaution is to keep
3
the high voltage below the maximum level
specified.
2. It is essential that serviceman have available at
all times an accurate high voltage meter. The
calibration of this meter should be checked
periodically.
3. High voltage should always be kept at the rated
value -no higher. Operation at high voltages
may cause a failure of the picture tube or high
voltage circuitry and,also under certain condi-
tions,may produce radiation in excess of
desirable levels.
4. When the high voltage regulator is operating
properly there
is no possibility of an X-radiation
problem.
Everytlme a color chassis is serviced,the bright-
ness should be tested while monitoring the high
voltage with a meter to be certain that the high
voltage does not exceed the specified value and
that it is regulating correctly.
5. Do not use a picture tube other than that
specified
or make unrecommended circuit
modifications
to the high voltage circuitry.
6. When troubleshooting taking test measurements
on a display monitor with excessively high volt-
age, avoid being unnecessarily close to the
display monitor. Do not operate the display
monitor longer than is necessary to locate the
cause of excessive
Voltage.
BEFORE RETURNING THE DISPLAY MONITOR
Fire and Shock Hazard
Before returning the display monitor to the user,per-
form the following safety checks:
1. Inspect all lead dress to make certain that the
leads are not pinched or that hardware is not
lodged between the chassis and other metal
parts in the display monitor.

2. Inspect all protective devices such as non-
metallic control knobs, insulating materials,
cabinet backs, adjustment and compartment
covers
or shields,lsoIatlon resistor-capacitor net-
works,mechanical insulators,etc.
3. To be sure that no shock hazard exists,checks
for leakage current in the following manner:
• Plug the AC line cord directly into a 12OV01t AC
outlet. (Do not use an isolation transformer for
this test)
• Using two clips leads,connect 1.5 kohm,10 watt
resistor paralleled
by a 1.5uF 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.
• Use a SSVMor VOM with 1000 ohms per-volt
or higher sensitivity to measure the AC voltage
drop across the resistor.(See Figure
1.)
• Connect the resistor to all exposed metal parts
having a return path to the chassis (metal
cabinet, screw heads, knobs and shafts,
escutcheon, etc.) and measure the AC voltage
drop across the resistor.
• Any reading of 0.3valt RMS (this corresponds to
0.5milliamp.AC) or more Is excessive and
indicates a potential shock hazard which must
be corrected before returning the display monitor
to the user.
SAFETY NOTICE
Many electrical and mechanical parts In this chassis
have special characteristics often pass unnoticed and
the protection afforded
by them can not necessarily
be obtained
by using replacement components rated
for higher valtage,wattage,etc.
Replacement parts that have these special safety
characteristics are identified in this manual,and its
supplement electrical components having such fea-
tures are identified by a&in the Parts List and
Schematic Diagrams.
Before replacing any of these components,read the
Parts List in this manual carefully. The use of sub-
stitute replacement parts that do not have the same
safety characteristics as specified in the Parts List
may create shock, fire,
or other hazards.
4
TO EXPOSED
METAL PARTS CONNECT
TO
KNOWN EARTH
GROUND
Figure 1. Leakage Current Test Circuit

THEORY OF OPERATION
GENERAL
Thismonitoris ahigh resolution monochromemonitorusingaamber,greenandwhitephospheredCRTwithetched
faceplate.
It receives one video signal and intensity signal, separated sync signals by TIL level. It can operate in all of the
MDAmode.
DESCRIPTION
1. MAIN BOARD
1-1, Power supply
This is a linear power supply using power trans(T701) and a monolithic integrated circuit voltage regula-
tion(IC01: L123CB or LM723).
The output voltage regulation is achieved by means of the error amplifier contained in IC01.
The output voltage of this power supply is fed back into the pin4 of IC01.
This voltage compared to the reference voltage internally.
The difference of this voltage control the output current of error amplifier .. D701 to D704 and
C705 form DC supplier circuit.
Q701 is current amplifier. R701 is shunt registor.
Q701 and R701 transfer current from DC circuit to load.
R703 is for minimum temperature drift. C707 and C708 is noise filter condenser.
Output voltage is fixed by adjusting VR701 variable resistor.
TEMP
COMPENS
ZENER
REF
AMP
6
INVERT
+ Vee INPUT
12 4
7 5
Vref -Vee NON
INVERT
INPUT
ERROR
AMP
+
2
FREQUENCY
COMPENS Ve
13 11
CURENT CURRENT Vz
LIMIT SENSE
BLOCK DIAGRAM OF IC01 (LM723 OR L123CB)
5
Vo

1-2. Horizontal and Vertical processor IC03
1-2-1, Horizontal processor
IC03 performs following functions.
Horizontal Oscillstor
Sync Seperator
Horizontal Predriver
Horizontal AFC
Shunt regulator
This sync signal is inverted by inverting transisot 0601 and is fed back into pin 15 of IC03, and flyback pulse
into pin 14 of IC03. This two signal are compared and the circuit is locked to a correctfrequency and phase.
1-2-2, Vertical processor
IC03 performs following functions
-Vertical oscillator
-Vertical predriver
-Vertical output
-Flayback generator
These are
two vertical controls. One is V-size control VR502, The other is V-linearity control VR503.
Vcc1
METAL PLATE
GND
16 14 13 12
11 10 9
Vcc2
BLOCK DIAGRAM OF IC03 (KA2133B OR fLPC1379C)
6

1-3, Horizontal Output Stage 0603
0603 is horizontal output switching transistor which closed during the scan period and open duringthe
flyback. It receives drive signal from IC03 through transistor 0602 and horizontal drive transT601. C616
makes the necessary S-correction. Because of the losses in the deflection yoke, a linearity correction
is
required. This is achieved by L603. The horizontal screen size can be varied by adjusting L602. The high
voltage of 13KV for
CRT anode is also generated in flyback transformer by using f1yback pulse.
1-4, Dynamic Focus
0604(BUV46 or KSC5021) is used to provide dynamic fovus voltage which is added to G4 voltage oftheCRT.
This voltage
is need to change G4 voltage according to the angle of the beam.
1-5, Video Circuit
This circuit performs following functions.
Video input buffer(IC02 : 74LS266)
-Cascade amplifier(0103,0104,0801)
-Contrast control circuit (0102, 0101, VR1 01)
If only video signal input into the IC02, IC02 delivered to cascade amplifier(0104, 0801).
If only dual signal input into the IC02, IC02 delivered to cascade amplifier(0103, 0801).
CONTRAST CONTROL is operated by 0101, 0102, 0801, 0103, 0104 form a cascade video amplifier which
circuit output
is applied to cathode pin of the CRT.
1-6, CRT Board
It contains video amplifier transistor 0801 and CRT socket.
1-7, Power Board
This board contains fuse.
IMPORTANT: When replacing the power supply, make sure that the green ground wire is properly attached
to the main chassis frame, and make sure that the fuae
is of the same type and rating as original.
7

DISASSEMBLY INSTRUCTIONS
REAR COVER·REMOVAL
1. Place the monitor upside down.
2. Remove 2 screw A ( MA467* ).
3. Remove 1 screw A (MA267*).
3. Pull the REAR COVER backward as pushing the 2points B in the direction of the arrows to separate from
the FRONT COVER.
CRT ASSY/CHASSIS FRAME ASSY REMOVAL
1. Remove the CRT's anode cap 1from the CRT.
2. Remove the CHASSIS FRAME from the FRONT CABINET.
NOTE: The CRT must be discharged according to the CRT discharge procedure in the important safety
precaution.
HOlOE~~~
icED
~/Ij£
1 (MATERIAL'STEEL PLATE)
FIG 1
8
FrGUHE 8. PCBS
CHASSIS - FRAME
FIG 2

-~ lr--o
J()-----.
=lA=6-
~
~
>c>
~
~
T.7
VIDEO ,I VIDEO
DRIVE
..
0103,0104
DUAL
\
VERT. OSC.
VERT
\ & OUTPUT
IC03
50Hz
HORIZ. OSC.
HORIZ
~
& DRIVE
IC03, Q602
~
AVR
...
0701. ICOl
717
VIDEO OUTPUT
0801
B+
HORIZ. OUTPUT FBT
-
0603
T602
18.432kHz
B+
12V
I
->/
I
I
r--
I
77
V-DY
~
H-DY
(')
I
»
(f)
(f)
CJ)
Z
o
G)
(f)
OJ
6
o
"
c
~
~
s:

ALIGNMENT INSTRUCTION
PLEASE READ BEFORE ATTEMPTING SERVICE
1. Line voltage must be kept within + /- 10 % of
the rated voltage.
2. Do not discharge, ARC, or measure high voltage
when high voltage lead is connected to CRT.
Discharge 2nd anode of CRT only after high volt-
age lead has been disconnected. Do not dis-
charge high voltage lead at anytime. This may.
results damage to transistor.
3. While the monitor is in operation, do not attempt
to connect or disconnect any wires.
4. Disconnect all power before attempting any
repair.
5. When the power is on, do not attempt to short
any portion of the circuit. This shorting may
cause damage to the transistors in the receiver.
ADJUSTMENT
Apply power and composite video signal (al-
phanumeric information) to the data display.
1. B+ ADJUSTMENT
1) Operate the monitor.
2) Connect the plus pole of DVM (Digital Multi
Meter) to the R701 (Shunt Registor) pin con-
nected to blue wire and connect the other
pole(GND) to chassis ground.
3) Rotate the B+ voltage adjusting control
VR(VR701) to provide a DC 12V.
4) Condition: Contrast, Brightness VR max.
2. VERTICAL FREQUENCY ADJUSTMENT
1) Instrument in use : Frequency counter,
Scope probe
2) Connect the GND pole of the scope probe
to chassis frame and the scope probe to DY
pin connected to black wire.
3) At self raster, adjust VRSOl so that the ver-
tical frequency Is 43 Hz. ( Free running
frequency : 43 + /- 1 Hz)
3. HORIZONTAL FREQUENCY ADJUSTMENT
1) Instrument in use: Frequency Counter,
Scope probe
2) Connect the GND pole of the scope probe to,
chassis frame and the scpoe probe to DYpin
connected to brown wire.
3) At self raster, adjust VR601 so that the horizon-
tal frequency is 18.432 KHz. ( Free running
frequency: 18432 +/- 500 Hz )
4. HORIZONTAL POSITION ADJUSTMENT
Adjustment horizontal phase control (VR602 :
Optional ) so that the image( or test pattern) is
placed on the center of the raster. If VR602 is not
used, this adjustment is not necessity.
5. IMAGE CENTERING ADJUSTMENT
1) Loosen the Deflection Yoke ( L401 ) clamp
and carefully move the yoke on the neck of
the CRT as far forward as possible Rotate
the yoke until the top and bottom edges of
the raster are straight. Tighten the clamp.
2) Center the raster by rotating the centering
rings.
6. VERTICAL LINEARITY ADJUSTMENT
Adjust the vertical linearity control( VRS03 ) until
the vertical linearity Is best.
7. VERTICAL SIZE ADJUSTMENT
Adjust the vertical size control (VRS02) so that
the vertical size of displayed pattern is 170 + /-
1.5 mm ( MA467*). If the monitor is MA267*
the vertical size is 150 + /- 1.5 mm.
8. HORIZONTAL WIDTH
10
Adjust the horizontal width control( L602 ) so that
the horizontal width of displayed pattern is 230
+/- 1.5 mm (MA467* ). If themonitor is MA267*,
the horizontal width Is 220 + /- 1.5 mm.

9. FOCUS ADJUSTMENT
Adjust the focus control (VR603 ) for providing
the best focus.
10. SUB-BRIGHTNESS ADJUSTMENT
PARTS LOCATION
Ol6o.
-.,-
1) Set the CONTRAST VR ( VR101 ) and
BRIGHTNESS VR ( VR605 ) to maximum
position.
2) Adjust the sub-brightness control ( VR604 )
so that the brightness is below;
* is WHITE CRT ( 1 ): 18 +/- 5 F/L.
VR601
~
H-HOLO
GREEN CRT ( 3 ): 28 +/- 5 F/L.
AMBER CRT ( 5 ): 25 +/- 5 F/L.
VR501 ~
0701
a
~
0703
V-HOLD
VR502D
I11III
0702
V-SIZE
c:>
I11III
0606
0704
0
Q604
VR~
fV•5O 'V
FO
gV-LIN.
0 0
!f
-+I-
~D
0604
0
....
0
VR701
....
CJ
0602
0
0501
D~
-f+-
VR604
SUB-BRIGHT
~
t~
C]
CD
0 0
Q601
[0705 *)
C[Pg02
0
Q501
CRT SOCKET
T601
0
(Q) 0
D~
QIO~
QI02
0 1
801
0
l0802
0
QI04
QIOI
0
F701
fC~1
I I I I 0
11

HORIZONTAL DRIVE
HORIZONTAL BLANKING
I·
8.3uS
~
11---_
-11-
O.56uS (Minimum)
54.25uS
1.10uS (Minimum)
44.29uS
20.02mS
VERTICAL DRIVE
-~I _----'
O.864mS
O.176mS
--.
-----
20.07mS
I
VERTICAL BLANKING
I I
r---I -----.,
L--~ __
~
9.96uS ·1
L-I _------II
..
I I
I~
1.04mS
~I~
1B.980mS ~I
(Minimum) (Maximum)
SIGNAL TIMING CHART
12

TROUBLESHOOTING GUIDE
Check power cord and switch
~
(
F701 Fuse open )
OK
8
Does 16.5V DC appear between Failure
of C705
C705 and GND?
D701,D702,D703,D704
YES 8
Does 12V DC appear on ( Failure
of Q701, IC01
)
collector of J701 ?
YES
13

Check video pre-amp and video
processing
circuit
Check video output
OK
Check G1 and G2 (630V DC)
voltage
( Failure of CRT, CRT Socket)
Check pin 8 of IC03
( Failure
of C511, V-DY
)
Check vert, synchronization
Check signal input
of vertical sync.
( Failure
of IC03, C504, C506 )
(
~
(
~
(
~
(
14
Failure of 0103,0104
IC03
Does VDC appear
between collector
of 0801
and GND?
Failure of D604, 0801
Failure
of D603, D605
Failure
of IC03
Signal cable loose or bad
)
)
)
)

WIRING DIAGRAM
"'
r\~ ____ ~1
MAIN-PCB
POWER TRANS
(V-DY)
BLACK YELLOW
O
H-HOLD V.HOLD '4 D701
VR601 VR501 f"'IIIII
L602 ~ ~ ~D703
DEFLECTION YOKE
\ \
~~: ~~J}) ~~~
D606 V-SIZE D ~D702
~ /"\ ~ ~ G4 G2 VR502 (i](i].
<./" . ~ ~ D704 [!]
___ 0604 [j Il~D603 V -= fo\
BRIGHT-VA
CONTRAST-VA
POWER SWITCH
SIGNAL CABLE
I \ o
WHITE BROWN
(H-DY)
FBT
l
T602
§,
r--
0
'"--
FOCUS _ ~I
VR603 VB~~~============~II~~I~======~======~
-l- ------~ D604
T0605
VL
WHITE
/
I-BLUE
RED-
PfT ....-
) j)
FUSE
0602
~
~~~~~~~~~'~~H_~DY~~~~~V-::
/ r-"" ~AC IN
r-T ...... -.~l
~
o~L*: ~D
~5~§~,\~1l1-- RED ~ T601 ril--l 0 0602
~
I-- YELLOW -t;'- 0105~ON2 VB1
O
I-- GREEN ....- 0 CONT ( ~
_--&l ___ --::~ ....... --=D~50:::::3--~ 0102
L..c' "
/ 0
It GRA.Y 0103 ~ •• 0102
t~, 01040
o
0101
0501
0601
o
0501
o
fiji CON4
~ BRIGHT
,---")VR604
CON~ SUB-BRIT
HB ~~ I
~II.. RED
11111
1111
/
/
BLACK
FI===&
~ED <t j)
nITnj ~ ~~/~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~G~R~EE~N~I-g~E_~~=~='-==============~~
i
WHITE BLACK )
II
\ '.)
• pin
Function Color 5 NC
~J II~L----~i~----~~
1 NG -6 Dual
2 Ground Black 7
Video
..
3 NC -8 Horizontal
4 NC 9 Vertical
15 16
1/
-
White
Orange
Yellow
Blue

CIRCUIT BOARD DIAGRAM (PARTS SIDE) CIRCUIT BOARD
DIAGRAM (Foil Side)
AC IN
(AC~20VI
(AC220/240V) (AC120V)
17
AC IN
(AC220/240V)
18
<5
....
....

MONITOR PC BOARD ASSEMBLY (SOLDER SIDE)
JlJl M
JUl
TR. NO.
TR.TYPE
3.3 Vp_p
240 V p-p
I . 3 Vp-p
13 V p- P
3.4 V p- P
0501
KSC815-Y
w
0601
KSC 815-Y
0602
2SD400F
-145Vp-p
3. I Vp P
0603 BU406
0701 TIP 42C
0801
C2682
700V p- P \ ICS IC03
VERT.OSC.
PIN NO.\
&OUT
1 4.4
2 6.2
lIT
3 3.3
4 10.4
225 V p-p
0.6Vp-p
5 1.13
6 1.77
7 11.57
8
6.29,
9 -
-480 Vp_p
32 V p-p
10 -
11
0.15
12
-
20Vp-p
o .7 Vp_ p
1flf M
II
I I Vp_ p
2.3Vpp
2.8 V p_p
13
-
14
-
15
-
16
-
19
Measured with high impedance V.T.V.M. or
circuit tester under line voltage 120V/220V/
240VAC Voltage reading may vary ±10%.
UNIT: Volts
FUNCTION
B C E
V-INPUT
0.65 0.3 0
H-INPUT
0.14
9.7 0
H-DRI
VE
0.36 9.28 14.6
H-OUT
0.06 18.4
4.5
AVR
13.9 12
0
VI-OUT
5.1 44
0
IC03 IC02 ICOl
HOR. DRIVE
INVERTER
POWER
REGULATOR
-0
5.1
-0 1.23
-0 1.2
-
7.34
0
-7.34
5.1
-7.34 0
-0 0
-0 0
0.5 0 0
0.82
0 0
-14.78 0
3.51 14.78
5.1
3.27 10.15
1.2
2.32
0
5.1
9.24
0 0
0 0 0
20

EXPLODED VIEW
28
MD-1467A
~4
12
II
6
5
4
3
21
22

EXPLODED VIEW
5
51
28
31
MD-1267 A
3
53
5
19
8
17
9
8
, 7
23
24