Archived from groups: rec.games.pinball (
More info?)
Coils do not "wear out". They can be physically damaged (errant screwdriver
pokes), they can overheat if they are energized longer than their duty cycle,
the insulation on the magnet wire can break down due to overheating, or the
magnet wire can break either at the terminal lugs or somewhere inside the
winding.
You can usually detect an overheated coil by discoloration on the coil
wrapper, or by visible signs of melting of the coil bobbin. Melting can cause
the bobbin to deform and interfere with free movement of the coil plunger.
As far as a coil "going bad" there's not a lot to check. Comparing the
resistance of the coil against another of the same type can sometimes indicate
if you've had insulation breakdown; a catastrophic failure often shows up as a
dead short or an open. Visible signs of overheating (discoloration, etc.) may
indicate a coil "going bad" due to insulation breakdown, but more likely would
indicate the coil is being driven beyond its duty cycle.
Joseph "Tony" Dziedzic
In article <1126666373.990616.289230@o13g2000cwo.googlegroups.com>,
drewgall@yahoo.com wrote:
>Is there a test to determine if a coil is "wearing out" or is going bad?
>