GolclStar
MONOCHROME MONITOR
SERVICE MANUAL
WTION
BEFORE SERVICING THE CHASSIS, READ THE “SAFETY
PREtXJTK)NS”, IN THIS MANUAL
MODEL:
MBM-2105GIA (MC-3 CHA=W
B GoldStar
FEATURES
l 2000 display characters in a 8 x 8 dot format.
l 18 MHz bandwidth, medium class, composite signal input.
l This monitor is compatible with a variety of home and personal computers
CONTROLS LOCATION
The MBM-2105GIA monochrome monitor uses a RCA jack connector.
The input signal is input through the RCA jack connector.
The input signal is based on the composite level.
Figure 2 shows the monitor controls on the front and rear panels.
\
r---
--
[
/
t
yLcPower
Indicator
H-Size
Video In
Contrast Brightness Power H-Position H-Hold V-Sue Power Cord
0
POWER (PUSH-ON)
Turn on the monitor by pressing the power switch.
The power indicator lights when the power is ON.
Always turn on the monitor before you turn on the
computer.
To turn the power OFF, just press this switch again.
0
Brightness
Turn this knob clockwise to increase brightness.
0
Contrast
Turn this knob
0
V-Size
Turn this knob to adjust the vertical size of the
picture.
clockvvise
I
Figure 2, Monitor Controls
NOTE: Monitor cabinet not used on 6300T Models.
to increase contrast.
0
H-Hold
Turn this knob to stop horizontal rolling of the
picture.
0
H-Position
Turn this knob clockwise to move the center of the
picture to the right; turn the knob counterclockwise
to move the center of the picture to the left.
0 H-Size
Turn this knob to adjust the horizontal size of the
picture.
CIRCUIT DESCRIPTION
1. VIDEO AMPLIFIER 2. POWER SUPPLY
The Fig. 3 details the cascade video amplifier.
Video amplification is provided by the TR303 and
TR304. TR303 and TR304 are connected in a
cascade configuration. TR303 operates as a
common emitter and TR304 operates in the
common base configuration. This minimized the
miller effect input capacitance and the difining
breakdown parameter for TR303 which becomes
BVCBO as opposed to BVCEO.
This enables selection of a higher speed/lower
breakdown transistor to be used in the video
amplifier.
The emitter of TR304 is driven by the collector of
TR303 which is a high frequency transistor.
Overall voltage gain for the stage is determined
by the ratio of R312 to R316. Bandwidth is within
3dB to 32 MHz.
The 120V AC line voltage is applied to the primary
of the T901 where it is stepped down through the
secondary winding to approximately 17V (AC).
After passing through the bridge rectifier circuit
and filter (C905) the regulated DC supply voltage
is approximately 18V (DC). The 18V unregulated
B+ voltage is applied directly to the collector of the
B+ regulator (TR901). A voltage divider network
(R905, VR901, R906) in which the B+ adjustment
control (VR901) is used to establish the desired
operating level (12V DC). When AC input voltage
variations occur, a correction voltage is produced
at the base of TR903 and is coupled directly to the
base of the error amplifier (TR902). This correction
voltage is then passed from the emitter of TR902
directly to the base of TR901 and B+ voltage
regulation is then accomplished.
TO@
c305
lOOuF/
TO
@
<
‘16V
R316
1
.ZK/ZW
TR304
3
KTC2229
R317
330
TR303
2N3904
C306
12OP
R313
47
R314
;
+
R309
75
L301
4.7uH
7
l
+
2~ C308
2.2uFll
l
TO
v
0
oov
TO
CRT CA.THODE
Figure 3, Video Ampllfler
Vertical
Oscillator
F,B)
vcc 2
Vetical Frame
Vcc 2 Generator
1
Oscillator
Frame-Synchro
Figure 4, BLOCK DIAGRAM OF THE TEA 2037A
1
Line Fly Back Phase
Input Detector
3. COMPOSITE VIDEO INPUT AND HORIZONTAL/
VERTICAL DEFLECTION
3-l VIDEO INPUT (PIN 15) 3-3
The detection level for negative sync pulse at the
sync separation input (pin 15) is set at 1.6V. When
the voltage at emitter of the Transistor (pin 15) is
above
1.6V, the transistor is cut off. Voltage
lower than 1.6V enables the transistor to conduct
and the internal circuitry
is
enabled for
synchronization function.
Generator
Vertical
output
Power
Amplifier
Input
Horizontal
output
Horizontal
Oscillator
LINE (H) OSCILLATOR (PIN 9)
The line oscillator is of the type which charges and
discharges a capacitor, since a perfectly linear
sawtooth wave form is not required.
The free running frequency is dependent on C705,
R705 and VR702 and is governed by this expression To = 085 x C705 x R705 where To is the line
oscillator free running frequency.
3-2 COMPOSITE VIDEO INPUT (PIN 15)
3-4
FRAME(V) OSCILLATOR (PIN 9)
Oscillator thresholds are internally fixed by
resistor C601, R603 are used to determine the
free-running frequency, the oscillator
free-running frequency is given by To = 0.15 x
C601 x R603.
ADJUSTMENT
1. REGULATED B + ADJUSTMENT
(VRSOl)
Connect high impedance voltmeter between
TR901
emitter and ground rotate the B +
adjustment control
12.0 2
2. FOCUS
O.lV.
(VR704)
(VR901)
to obtain a reading of
Adjust the focus control (VR704) for best overall
focus of the test pattern (marked with the symbol
“%“). Usually the center and corners of the
screen do not focus at the same setting and a
compromise must be made.
3. VERTICAL
SIZE (VR601)
The vertical size control (VR601) should be adjust
for the picture to fill the screen vertically.
4. HORIZONTAL SIZE
(L703)
The horizontal size control (H-site coil) should be
adjusted for the picture to fill the screen horizontal-
ly.
5. HORIZONTAL POSITION NR701)
The horizontal position control (VH701) snould be
adjusted for the horizontal picture position.
6. SUB-BRIGHT (VR703)
Adjust subbright control (VR703) for
visual
of the raster when external brightness is turned to
maximum
7. CENTERING ADJUSTMENT
It the raster is not centered horizontally and verti-
cally it may be centered by removing the cabinet
back and adjusting the centering tabs on the neck
of the tube, located at the rear of the deflection
yoke. Turn the whole device clockwise or
counterclockwise. To increase the amount of raster
shift move the two tabs which project from the
device farther apart, if raster is tilted on an angle,
it may be straightened by loosening the deflection
yoke clamp and rotating the deflection yoke.
cut off
V,deo Input
0
AC
12OV
60Hz
BLOCK DIAGRAM
Video
Preamphf~er
TR301.
TR302
TEA 2037A
LllW POW&Y
Filter TMlS
Video Output
TR303, TR304
PW+.?r
REG.
, +12v
SCHEMA1
CONTRAST
VR301 5008
-
I
-
R602
15
!
-
4
c905
0901-0904
lN5392GP.4
-
3
-
t-
F901 20.6
T750mA 25OV
1
IUL/CSAI
1315mA25OV
A
NDE/SEtlKOI
2200/2!
TR902
Kltl959-O/Y
12.7
C908
..-
+y-+$ll.2
H.HOLD u
VR702
b.lK
MnJ%-
H.V
TEA2037
I
OEFL
4th
R705
33K
12Ul
2
u
-
1
A
NOTES: 1. RESISTORS ARE SHOWN IN OHMS
K = 1.000
2. CAPACITORS ARE SHOWN
IN UF OTHERWISE NOTED P : cc Ir
3. All RESISTORS ARE f
TOLERANCE UNLESS OTHERWISE NOTED
I
M = 1.000.000
5%
B
I
u
THE
SYMBOL
FEATURES IMPORTANT FOR PROTECTION FROM X-RADIA
ELECTRICAL SHOCK HAZARDS. WHEN SERVICING IT IS
ONLY MANUFACTURER’S SPECIFIED PARTS BE USED
COl’lPONENTS IN
4
ItlPORTANT SAFETY NOTICE
MA RK OF THIS SCHEHATIC DIAGRAM
THE&YUBOL
MARK OF THE SCHE
INCOI
C
b
F
DIAGRAM
01G.h
,
OwLI/
loowl tl.OUl
RIM
‘711
c717
c708
L.7/50
R719 :
I
1
*
R7OI 1 1
L.wv
20
3
_.
3OvI+ IHI
23VI-r IV1
N-i
/
9lOKGB3UGREENl
mKGB4*wmENl
9lDKMUBLACK/WHTE)
9lDKGB
39 IYELLOWISH
RltO
b7K
VR703
BRJT.
R711
l5K
070)
RGPlOD
c7l4
5OVP-P
0
;
l
0.01 /
lK
Lltw
R7u
33K
/-
-
;;,2
&l/l5
f
,/,6ti cn@
H.LW.
FBT
7701 A
o%ll
1’05 5 c7l5
u3wl
!rl!JE
A
6‘3
M/VI
GREEN1
FOilIS
&lb
R7K
R7Y
6.Y
cm
lw/
100 ‘?
!!z’
1ooK
vR705
2sOKn
EXT.
BRIT
&
TES
SPECIAL
FIRE AND
IllAL
THAT
iE
CRITICAL
D
\
LA m SYMBOLE MARQUE DE CE DIAGRAMME SCHEIIATIQUE COMPREND DIIIPORTANTES
CARACTkRISTIQUES
DES DANGER S
51
DES PIiCES DE CETTE A SYMBOLE MARWE DOlfENT
N’UTILISEZ WE DES
I
\
\I-Ln
4
IMPORTANT AVIS SUR LA
SPkIALES
D~NCENDIE
PIkES SPkIFItES
CON$UES POUR PROTiGER DES RAYONS X.ET
ET DE SECOUSSES ELE~TRIQUES. EN
E
(BOOST UP1
3Vr-r
PAR LE HANUFACTURIER.
\
IHI
SkURlTi. b
‘--
ETRE
cAs
DE BEsolN
REIIPLACE’S
2oovp+
IH’
484-309A
F G
YES
TROUBLESHOOTING GUIDE
I
D706,
TR902, TR903. D905.
TR901 AND POWER
REG CIRCUIT
~.
c713. c714. c715
7
, CHECK CRT (GZ) VOLTAGE 450V
2 CHECK CRT (HEATER) VOLTAGE 12V
YES
CHECK CRT CATHOD VOLTAGE
45-55v
YES
VR703 (SUB-BRIGHT,, R710. R711.
VI?,05
(MT
BRIGHT,,
TRW,
“R301
TR302. VIDEO CABLE
NO
ABOVE 55V TROUBLE IN
(CONTRAST,,
TROUBLE IN
-,
FBT.
CR706
LEAD (HI,. LEAD
*
TR303, TR304. R311. R309. R310.
R315, R314, R312
R712
(Vl,
V2)
HORIZONTAWERTICAL
SYNC TROUBLE
SYNCTROUBLE
TROUBLE IN
R719. C716. R70B, R720.
I
REF. NO.
TR301. TR302.
TR902, KTC 1959
TR903.
TR601 KTC 1815
FIGURE OEBCRIPTION
B
w
L
-C
KTC ,015
KTA 562TM
TR304
I
TR701.
TWO1
IC701
l@a
t B
k
c
>
9
BCE
KTC 2229
BU 806
KTD 880
TEA 2037A
I
TR303
-0
E
2N 3904
PRINTED CIRCUIT BOARD
1. MAIN PCB
ASSY PIN: 1
lo-BOW
J
GSEP-2112
TI
BLACK
ASSY PIN: ilO-B72A
3. MAIN PCB (SOLDER SIDE)
4. LINE FILTER PCB (SOLDER SIDE)
O-0
Lsol
I
EXPLODED VIEW
REPLACEMENT PARTS LIST (MECHANICAL PARTS)
*Outer Cabinet not used on 6300T Models.
C
D
I
8
1
3X3-A02A 1 COVER
9
___
10 407-622A
11
12 303.924A
13
.-
407.696A,I-LAIE.,
303.928A [ COVER, PCB SHIELD CASE
1
COVER,
ASSY.
“x-t
CRT
E
, 1ILr.I
w
B&
WNR ruvvcn,
BOARD I
I
1
F
REPLACEMENT PARTS LIST
CAUTION: Components identified by the A symbols in the PARTS LIST and on the SCHEMATIC DIAGRAM
have special characteristics important to safety.
Do not degrade the safety of the set through improper servicing.
ABBREVIATIONS:
Capacitors . . . .
Resistors
(All CC and Capacitors are +
REF.NO.]PART
R301
Fi302
R303
R304
R305
R306
R307
R308
R309
R310
R311
R312
R313
R314
R315
R316
R317
R318
R319
R320
R321
R601
R602
R603
R604
R605
R606
R607
R608
R609
R610
R611
R612
R613
R701
R702
R703
R704
R705
R706
R707
R708
NO. 1 DESCRIPTION
RESISTOR
RD.
118W
RD.
118W
RD.
118W
RD.
118W
RD.
118W
RD,
118W
RD.
118W
RD
118W
RD. 1/8W 10K ohm
RD.
118W
RD
118W
RD.
118W
RD.
118W
RD. 1/8W 2 4K ohm
RD.
118W
RD 2W 1 2K ohm
RD.
l/SW
RD.
l/SW
RD.
118W
RD
118W
RD.
118W
RD.
118W
RD.
118W
RD.
118W
RD.
118W
RD.
118W
RD.
l/SW
RD.
118W
RD. 1/8W 82K ohm
RD.
118W
RD.
118W
RD.
118W
RD.
118W
RD.
118W
RD.
118W
RD.
ll8W
RD.
118W
RD.
118W
RD.
118W
RD.
118W
RD.
118W
RD.
112W
CC: Ceramic (TC), CE: Chemical, CK: Ceramic (Hi-K),
BP: Bipolar, CQ: Mylar, PE: Polyester, PP: Polypropylene
. . . .
RD: Carbon Film, RS: Metal Oxide Film
5%,
50 Volts and all resistor,
S:
Recommended Service Parts, R: Replacement Service
REF. NO. PART NO. DESCRIPTION
A R904 RWR, 7W 18 ohm
75 ohm
120K ohm
82K ohm
680 ohm
220 ohm
390 ohm
100 ohm
56 ohm
1 3K ohm
75 ohm
82 ohm
47 ohm
3 3K ohm
330 ohm
120 ohm
1 OK ohm
100 ohm
4 7K ohm
33 ohm
1 5 ohm
560K ohm
2 2 ohm
18 ohm
150K ohm
390K ohm
2 2 ohm
1 OK ohm
82 ohm
6 8K ohm
150 ohm
150 ohm
560K ohm
3 9K ohm
47K ohm
33K ohm +20/o
470 ohm
33 ohm
6 8K ohm
REMAR
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
A
R
R
R
R
R
R
R
R
R
R
R
R
+5%,
R709
R710 RD. 1/8W 47K ohm
R711
R712 RD.
R714 RD.
R715
R716 RD.
R717 RD,
R718 RD.
R719 RD.
R720 RD.
R901 RD. 1/8W 2 2K ohm
R902 RD. 1/8W 75K ohm
R905 RD.
R906 RD.
R907
VR301 VARIABLE 5008
VR601
VR701
VR702
VR703
VR704
VR705
VR901
c301
C302
c303
c304
c305
C306
c307
C308
c309
c310
C601
C602
C603
C604
C605
C606
C607
118W
unless otherwise noted).
PatIS
RD.
118W
820 ohm
RD.
118W
15K ohm
118W
33K ohm
118W
10K ohm
RD.
118W
IOOK ohm
118W
6 8K ohm
118W
33K ohm
li8W
15K ohm
118W 1
8K ohm
118W
6 8k ohm
118W
390 ohm
118W
560 ohm
RD.
118W
560 ohm
SEMIFIX
SR 29R 2208
SEMIFIX
SR 29R 1KB
SEMIFIX
SR 29R 4 7KB
SEMIFIX
SR 19R 1OOKB
SEMIFIX
H162lC 3 3MB
VARIABLE 250KB
SEMIFIX
SR 19R 2208
CAPACITOR
CE, 47uF 16V
CE, 22OuF 16V
CE, 22uF 16V
CE, 47OuF IOV
CE. 1OOuF 16V
CC, 12OpF 5OV
CE, 47uF 1OV
CE, 22uF IOOV
CC, IOOpF 50V
CE, IOuF 16V
CO. 0 22uF IOOV
CE. 22OuF 16V
CE. 47uF 16V
CO, 0
IuF
IOOV
CE. 1OOOuF 16V
CO, 0 22uF 1OOV
CO,
OOOluF
1OOV
3EMARl
R
w
R
R
R
R
R
R
R
R
R
R
H
S
R
Fi
R
S
S
S
S
S
S
S
S
R
R
R
R
R
R
R
R
R
R
S
R
R
S
R
s
R
REF. NO. PART NO.
C608
c701
C702
c 703
c704
c705
C 706
c707
C708
A
C709
CT10
(1711
c’712
C713
c714
A C715
C716
c717
c-718
c90
1
cc)02
c903 CK, 0
c904 CK, 0
c905
C906
C908
A c91o MPP. 0
A
C911
A c912 CK, 0
D301
D601 1 N4002
D602
A D603
D604
D701
A D702
D703
D704
D705
A D706 19-0048
A
D901
A 0902
A D903
A 0904
1
g-0053
1
g-0052
1
g-0051
1
g-0050
1
g-0049
1
g-0047
A D905
P902
TR301
TR302
TR303 2N3904
TR304
TR601
A TR701
19-0046
1
g-0045
1
g-0044
DESCRIPTION
CE.
2
CE.
1OOuF
CO, 0
CE. 1
CO, 0
PP 0
CO, 0
CQ.
0
CE, 4
PP. 0
CE,
47OuF
CE.
22OuF
BP. 4
CE,
IOOuF IOOV
CE,
1OOuF 1OOV
CK. OOluF
CC. 56pF 50V
CO, 0
CK. 0
CK, 0
CK,
0
CE,
22OOuF
CK, 0
CE, 47uF 16V
CK, 0
I c.
DIODE
KDSl555
KDSl555
ZENER 62x83.C6V2
KDSl555
KDSl555
RGP25D
RGPZOG S
RGPlOD
RGPlOD
RGPlOM
1 N5392GP S
1 N5392GP
1 N5392GP
1 N5392GP
ZENER
LED (GREEN)
TRANSISTOR
KTC 1959-Y
KTA562 TM-Y
KTC2229-Y
KTC2240.GR
BU806 S
2uF
160V
16V
1uF 1OOV
OuF
25V
0022uF 1OOV
0022uF
200V
0022uF 1OOV
015uF 1OOV
7uF
25V
027uF
400V
25V
16V
7uF
25V
1OOOV
0047uF IOOV
OluF
50V
0047uF
50V
0047uF
50V
0047uF
50V
0047uF
50V
25V
1uF
50V
1uF
125V
0022uF 125V
0022uF
125V
BZX83-C6V2
REMAR
R
R
s
R
R
S
R
R
R
s
R
R
S
R
R
R
R
R
R
R
R
R
R
R
R
R
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
COIL
L301 20-0040
L302
L701
L702
L703
L704 20-0038
A
L901
Q
A 1 l-0023
A T701
A
A
F901
A
S901
NE301
SG301 SPARK GAP
VIDEO IN JACK, RCA PHONE
SIGNAL
CABLE
Vl. v2 WIRE ASSY SHIELD
“j&c hl c\l
. .
20-0039
07-0009
fd IcySAC POWER CORD
OO-6300-5?T PC
t,> s
-
PEAKING PL 4
PEAKING PL 3
CHOKE
H~LINEARITY
COIL WIDTH
PEAKING PL
LINE FILTER
MISCELLANEOUS
CRT,
CRT,
FBT S
DY
PCB MAIN
FUSE 0
SWITCH, POWER
IOuH S
310KG531
310KGB4A
ASSY
75Ai250V
NEON LAMP 95V
RCA TO RCA CABLE
SOCKET CRT
TRANS. POWER SHIELD
PWB LINE FILTER
BOARD COMPL. W/TRAY
CONNECTOR ASSY FOR
77
CONNECTOR ASSY FOR LED
PRINTED MATTERS
KIT, PRINTING
OWNER’S MANUAL
PIN. STAPLE NO 10
BAG, PE
3
77-7
J-
7uH S
3uH S
1OuH S
(Green)
(Amber)
TR901
S
S
S
S
S
S
S
S
S
S
R
R
R
R
R
S
R
R
R
R
R
R
R
R
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