I have three books on repairing EM machines and not one of them tackles the
problem of finding shorts. Finding a short is easy if the machine has a
fried coil or wire, but what if everything looks good under the hood? The
best way I have found is the process of elimination. Turn the machine off and
unplug all the wire harnesses from the head and the playfield. Install a
correct new fuse, and restart the machine. Fuse blows? The problem is in the
body. If it doesn't, unplug the machine and plug in one block of wires at
a time and restart each time until the fuse blows.
Unplug the machine and install another fuse. Plug in all the blocks except
the suspected bad one. Using a jumper wire, connect one pin at a time on the
block to its female counterpart, and restart. Repeat this process on each
pin until the fuse blows. Now you have found the line that is causing the
trouble. Follow that wire color to each connection it makes. I use colored
paper adhesive dots that you can find in any drug store and mark each
connection. Start eliminating sections of that circuit and keep narrowing it
down and you will find the cause. It may take you a couple of evenings work,
but it will be worth it. You will know that you can tackle any problem with
that machine and ace it.
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