Star Tech Journal

STAR*TEcH
January 1996
Journal
... continued from page 13
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The HOT is readily identified,
and the only other power semi-
conductors in most monitors will
be the regulator in the power sup-
ply and the vertical sweep driver.
~
F.Y.I. STAR*TECH Journal
pays for itself over and over again.
One tech tip many times is worth
a years subscription -or more.
It's as important as any tool in
your shop.
When your coin-op game goes
down, turn to STAR*TECH
Journal to save yourself valuable
time and money.
...
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Points Covered
Look up the part numbers in the
ECG or NTE cross reference
guide. Not only will the ECG
book identify your vertical out-
put IC, but it will provide the
pinout as well. That is the func-
tion of each pin on the device.
1
Intro, troubleshooting phi-
losophy, general approach,
cautions.Three types of
problems described:
Monitor blowing fuses
T'shooting horiz section
T'shooting power supply
Look up your voltage regulator
IC and the book tells you the
output voltage to expect. There
are three color circuits in any
monitor, so when you spot three
similar looking circuits side by
side on the PC board, you have
probably found the video or
color circuits.
Line filter. Isolation prob-
lems. Discussion of ap-
proaches to locating and
identifying components
and circuits.
PC board art
Silk screening
Component types
Literature resources
SIMILAR PRINTS
2
Color/Video problems:
Color gun circuits
CRT
Neck board
Vertical section. General
discussion on capacitors:
High and low voltage circuit
types. Horizontal section.
Horizontal deflection -it
ain't the yoke. Pincushion.
REFERENCES
r
Monitor Repair
Without
Schematics
Other schematics can be helpful.
If you can find another monitor
using the same oscillator IC, use
that schematic for clues as to what
voltages and waveforms to ex-
pect on the mystery unit. That
will work for circuits close to the
IC anyway. Even an unrelated
schematic an be helpful to sug-
gest component functions to look
for.
Part Two to appear in next issue.
See chart on right for topics.
£:1 tY :ti, fi:l
Journal
PART
PART
"Dead" monitor or blank
screen: No power. Bad
power or poor regulation
and associated techniques.
Shutdown: Oscillator tech-
niques. Heat related prob-
lems.