STAR*TECH
Journal
September 1 996
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
s.o.s.
SAVE OUR SWITCHERS
(PART
1)
Much of our equipment is powered by a switching power supply these days. Though linear
supplies are alive and well in pinballs, elsewhere they are being replaced more and more by
switchers. Some equipment uses both, for example redemption equipment using a switcher
for logic and sound supplies and linear supplies for the motors. (This is the first of a series)
Frx 'EM?
Why should we fix switchers any-
way, they aren't expensive?
Once you have done a few, most
repairs are done in ten or fifteen
minutes. If it needs more time
than that, don't bother, give up
and throw it in the parts scrap.
I'm the kind of guy who doesn't
care to participate in throw-away-
America any more than neces-
sary, so I make the effort. If noth-
ing else, a handful of parts in the
tool case lets you repair them in
the field. This is almost like hav-
ing an extra supply in your kit.
As with anything else, it is valu-
able to consider cost vs. benefit.
There is no point in spending half
a day on something so inexpen-
sive, so I give it a shot, and if that
fails I move on to other repairs.
RIGIIT
Toor.s
You really do need an oscillo-
scope to work on these. A meter
will never respond to the fre-
quencies here: You could have
three volts of high frequency
ripple on the output and your
meter would just think it had
plain old 5V de. The most basic
'scope will do, it doesn't even
need to be triggered. After all, all
we will be 'scoping is DC and
ripple.
Fl
3A
RI
THEORY
Just enough to get us through the
job. Aside from repair consider-
ations, the difference between
switchers and linear supplies is of
little concern to us. They do the
same job. With the exception of
counter top games, space is rarely
a factor. We need concern our-
or
Tl
Fl;>ol'!
C.ONrftdL ~ - T - - P - - - , Y - - M
Cnt,:c,11"
C4
'
T3
07
Cl2
2.
...
3
08
+
470f.t.
IG.V
~uP.,.I.V' Fo~
Co.,TllO/,.
'£:C