Star Tech Journal

Issue: 1996-July - Vol 18 Issue 5

STAR*TECH
Journal
July 1996
CD
Enzo's
Tech
Tips
"Hey Enzo, I can't find the self-test button on this Captain Fantastic!,,
Douglas 'Enzo' Mccallum • Shiawassee Technical Services • Lansing, Ml
REPAIRING BROKEN
PC BOARDS
r
It happens to the best of us.
You are shopping out a game and discover a circuit board with a crack running through it.
Worse yet the board is completely broken in two. What do you do?
You can rant and rave, point fingers,
get mad and holler. Or ...
Mainly there are two things to
consider: First, why did it happen
and how to prevent it, and sec-
ond how do we fix it.
This article is about repair, but
a few words about prevention
won't hurt. If the damage is due to
vandalism, make sure your cabinets
are secure. After all, there are no
PC boards exposed to the outside
world on the games I have seen.
If something like a cash box lid
or a switching power supply went
flying around in the game dur-
ing transport and broke some-
thing, you have to ask why. Was
the power supply loose because
someone was too lazy to install
ALL the mounting screws?
If you aren't using the cash lid,
why not remove it from the game
and store it in the attic. While you
are in there, clean out the bot-
tom of the game. Loose coins and
hardware have a habit of finding
the fuse holders and other con-
nections to short out.
WHAT IS 1HE MOSf COMMON BRO-
KEN BOARD?
In my experience,
way out in front of all the others
is the CRT neck board on the
video monitors. (CRT is Cathode
Ray Tube, the picture tube.)
And why not? It does stick out
into space, an easy target. Let us
all be thankful for the newer
monitors with the protective
frames, something Nintendo
(Sanyo) had years ago.
Make it a policy never to lean a
back door against the back of an
open cabinet. It takes very little
to knock a door panel into the
works where it can take out a
neck board in a flash. When your
monitor is out of the cabinet, and
especially when the monitor is in
transport, make it a point never
to leave the unit sitting where
someone else can run into it with
a hand truck, or knock a door
panel over onto it, or even catch
a pant leg on it. Make. sure the
monitor is secure in the cabinet
(yes, ALL the bolts) so it won't
shift during transport. The force
that can break a neck board in
two can also easily crack the neck
of the tube. When air gets in
there, bye bye CRT.
AssESS 1HE DAMAGE
The first step in PC board repair
is to decide what is wrong and
what needs to be done. If the
problem is a main logic board
snapped in half across the
middle, lay it gently on the boss's
desk and go on to your next
project. Obviously we need to
decide if repair is feasible, and
weigh the time and expense
against the value of the board.
Neck boards are pretty basic, and
they can be repaired easily
enough even if shattered into
... continued on next page.
July 1996
CD
STAR*TECH
... continued from previous page.
three or four pieces. The damage
looks worse than it really is. Of
course if you have a few spare
parts monitors in the shop, it
probably makes more sense just
to replace the board with another
one. It is just a few wires to sol-
der.
Consider that the neck board
simply provides a place for some
transistors around the CRT
socket, its mechanical strength
isn't critical, it doesn't support
much more than itself.
Contrast that to the board on a
Deltronics ticket dispenser. This
little board is simple and easy to
repair, but it also must support
the ticket notch optical sensor
Journal
Monitor
Proble111s?
worry if the connector is going
to be parted and reconnected
from time to time. In these cases
it is sometimes wiser to extend
the connector away from the
board a few inches on wires
which can be anchored to the
frame or chassis. The connectors
are then mated in mid-air thus
eliminating any stress to the
weakened board.
Order This Tech Pub
.JVIONITORS:
SYMPTOMs/SoLUTIONS
Includes all S* TJ monitor
articles from 1990, 1991,
1992, 1993, 1994, 1995
& 1996
REPAIR STRATEGIES
We patch boards broken in two.
Cracks on a board not com-
pletely broken need to be
stopped to prevent their spread.
0
0
0
0
0
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Sometimes we can bypass the
damage. If the comer snaps off a
board and we find that a few
traces were just following the
"If the problem is a main logic board
snapped in half across the middle, lay
it gently on the boss's desk and go on
to your next project. "
1990
1991
1992
1993
1994
1995
1996
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Save over 30% order the
□ Entire set for $69. 95
Name:
------------..
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and keep it in position. Mechani-
cal strength is more important
here, so the kind of damage
would affect your decision to re-
pair or replace.
The worse case is the board bro-
ken where a connector can stress
it. An example would be the sig-
nal input connector near the cor-
ner of the main board of a video
monitor.
Connectors don't stress the board
by themselves, we only need to
edge of the board around the
comer, we would have to repair
the same traces twice as each
crosses either end of the break.
In this case it might make more
sense to jump past the corner
with wires.
When we attempt repair of a bro-
ken board we are doing two jobs:
First we are restoring some mea-
sure of mechanical strength and
structural integrity, second we are
restoring all the broken electri-
... continued on page 10
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