Goldstar Mbm 2105 Monochrome Service Manual

GolclStarMONOCHROME MONITOR
SERVICE MANUAL
WTIONBEFORE SERVICING THE CHASSIS, READ THE “SAFETYPREtXJTK)NS”, IN THIS MANUALMODEL: 
MBM-2105GIA (MC-3 CHA=W
B GoldStar 

FEATURESl 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 LOCATIONThe 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-SizeVideo InI...

CIRCUIT DESCRIPTION1. VIDEO AMPLIFIER2. 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...

Vertical
OscillatorF,B)vcc 2Vetical Frame
Vcc 2 Generator
1 Oscillator 1Frame-SynchroGenerator
Line Fly Back Phase
InputDetectorHorizontal
OscillatorVertical
output
PowerAmplifier
Input
Horizontal
output
Figure 4, BLOCK DIAGRAM OF THE TEA 2037A
3. COMPOSITE VIDEO INPUT AND HORIZONTAL/
VERTICAL DEFLECTION3-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
above1.6V, the...

ADJUSTMENT1. REGULATED B + ADJUSTMENT 
(VRSOl)Connect high impedance voltmeter between
TR901 emitter and ground rotate the B +
adjustment control 
(VR901) to obtain a reading of
12.0 2 
O.lV.2. FOCUS 
(VR704)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...

-
I
-
!
-
4
-
3
-
2
-
1
SCHEMA1
CONTRASTVR301 5008
t-
c9050901-09042200/2!
lN5392GP.4
1F90120.6T750mA 25OVAIUL/CSAI1315mA25OVNDE/SEtlKOI
TR90212.7Kltl959-O/YC908R602
15H.V OEFL..-
+y-+$ll.2TEA2037
MnJ%- 4thH.HOLD uR705
VR70233Kb.lK12Ul
INOTES: 1. RESISTORS ARE SHOWN IN OHMS
K 
= 1.000M = 1.000.0002. CAPACITORS ARE SHOWN
IN 
UF OTHERWISE NOTED P : cc Ir
3. All RESISTORS ARE 
f 5%TOLERANCE UNLESS OTHERWISE NOTED
u u4 ItlPORTANT SAFETY NOTICE bTHE 
SYMBOL MARK OF THIS SCHEHATIC DIAGRAM INCOIFEATURES...

DIAGRAM3OvI+ IHI/
N-i23VI-r IV19lOKGB3UGREENlmKGB4*wmENl9lDKMUBLACK/WHTE)
9lDKGB 39 IYELLOWISH GREEN1/-5OVP-P 
M/VI
-H.LW.0 ;
RltOb7KVR703R7K 1ooK
BRJT.R7u33K
R711l5KR7Y
6.Y070)
cmRGPlODlw/100 ‘?
01G.hR719 :vR7052sOKn
EXT.
BRIT
f
;;,2 ,/,6ti cn@FBT
&l/l57701 A
,*I 1
c717R7OI 1 1OwLI/L.wvloowltl.OUlc708
3
20L.7/50 _.c7l4o%ll l!!z’FOilIS1’05 
5 c7l5
!rl!JE
u3wl 0.01 / AlKLltw6‘3 
&lbRIM‘711
\\(BOOST UP1
\
&\I-Ln 3Vr-r IHI‘-- 2oovp+ IH’
4 IMPORTANT AVIS SUR LA SkURlTi. b
TES SPECIAL
FIRE AND
IllAL THAT
iE...

TROUBLESHOOTING GUIDETR902, TR903. D905.TR901 AND POWER
REG CIRCUIT~.7
ID706, 
c713. c714. c715YES
, CHECK CRT (GZ) VOLTAGE 450VNOTROUBLE IN
2 CHECK CRT (HEATER) VOLTAGE 12V
-, FBT. CR706 R712
LEAD (HI,. LEAD (Vl, V2)
YES
CHECK CRT CATHOD VOLTAGEABOVE 55VTROUBLE IN
*45-55vTR303, TR304. R311. R309. R310.R315, R314, R312
YESVR703 (SUB-BRIGHT,, R710. R711. 
“R301 (CONTRAST,,VI?,05 (MT BRIGHT,, TRW, TR302. VIDEO CABLEHORIZONTAWERTICAL
SYNC TROUBLEISYNCTROUBLE
TROUBLE INR719. C716. R70B, R720.
I
IREF....

PRINTED CIRCUIT BOARD
1. MAIN PCBASSY PIN: 1 lo-BOW
ASSY PIN: ilO-B72A
JGSEP-2112TIBLACK 

3. MAIN PCB (SOLDER SIDE)
4. LINE FILTER PCB (SOLDER SIDE)
O-0
Lsol
I