Star Tech Journal

Wico Switching Supply Repair Procedure
Frank 'The Crank" Seninsky
Alpha-Omega Amusements & Sales
Edison, New Jersey
Our techs will generally replace a switching
supply (+5v @ 7 amps, 11 amps and 15
amps) in the field and drop the bad one off at
the shop. A power supply only costs around
$30.00 and all the techs carry extras just
like they carry fuses. In fact a power supply
is nothing but a BIG FUSE (it works or it
doesn't). If you want to fix them in the field
here are some basic rules to follow:
Our shop tech has repaired about 25 power
supplies in the last few months following the
above simple procedures. That's a savings of
$780, -$900 (30 x $30) less $120 (6 hours
labor @ $20 /hr)! And the parts were FREE.
Now please don't go and waste countless
hours (time is money) trying to fix the 25% of
the power supplies that have a blown fuse.
1. Remove the outer casing.
2. Check if the fuse is blown. If the fuse is
open (about 25% of the time) chances are
the problem(s) is extensive, so keep this
power supply for spare component parts
(diodes and caps mostly).
3. If the fuse is good, check C6 (330uf-35v)
radial cap. The top of it is probably ripped
open. Do not replace C6 just yet.
Drew's Tiger Paw
Cranes Claw Adjust
Service Department
Drew's Distributing
Fairforest, South Carolina
4. Next check Cl6 and Cl 7 both (1000uf-
16v or 25v). C6, Cl6 and Cl7 have the 3
highest failure rates in Wico power supplies.
5. Also check C4 and C5 both (100uf-200v),
Cl7 (3300uf-16v or 15v) and Cl9 (3300uf-
16v or 25v).
6. Replace the caps that look or test bad.
7. Apply AC to the supply and put a LOAD
on the DC outputs and adjust to +5.25vdc.
Most often (about 75% of the time) C6 and/ or
Cl5 and Cl6 are the only components that go
bad. You will see green sticky stuff under the
caps or bloating of the top or bottom of the caps.
These caps can be replaced in a few minutes.
PROBLEM
This is an adjustment fyou can make if you
are having complaints of your Tiger Paw
Cranes lowering over a piece of plush, and
start to raise before the claw fingers close.
This appears as if the crane has cheated the
player.
SOLUTION
To remedy this, loosen the flat head screw at
the bottom of the claw, and tum the cam that
brings the fmgers closer together. Now re~
tighten the bottom screw. This moves the
plunger up further into the solenoid and
eliminates the slight hesitation in the clos-
ing of the fmgers.