Star Tech Journal

January 1996
CID
STAR*TEcH
Main PCB Silkscreen
Silkscreening
Shows
Monitor
Monitor Power Supply
Journal
Though a monitor circuit board
looks complex, we are often con-
cerned with only a small part of
it at a time, and it is not too diffi-
cult to follow the printed circuit
traces to make up your own sche-
matic, even if it is just in your
head.
Some manufacturers identify
power supply traces on the PC
board with silk screen hatch
marks or a solder stripe down the
center of an otherwise coated
trace. Learning to trace out your
own schematics will be valuable
in many ways in your bench
work. A little practice makes it
fairly easy.
NUMBER GROUPS
Typical Monitor Power Supply Using Regulator IC
Monitor Power Supply
tOOV AC W'° It•
TSX 1129 -I
I
Many brands give different num-
ber sequences to each section of
the monitor. Part numbers might
group horizontal section parts in
the 600s, power supply in the
900s, and vertical in the 400s for
example. Check the numbers silk
screened on the PC board.
You may find not only these
number groupings, but on some
boards even lines surrounding
the various sections with labels
like VIDEO, SYNC, VERTI-
CAL, etc. Component types and
values can suggest their function.
Electrolytic caps of high voltage
rating (160V, 250V) and a value
of 10 ufd or more are likely filter
caps or maybe a vertical output
cap. Vertical sweep outputs are
usually pairs of transistors on
heatsinks, or on newer units a
multi pin IC for that purpose.
Typical Monitor Power Supply With Discrete Regulator
... continued on page 14