Dear Will,
The Dayton 4C761 blower in the Commander 2500E amp
has a coil DC resistance of 14 ohms. My Fluke 36 clamp
a.c. ammeter does not register even one ampere draw
when the motor is turning.
The armature has a back-and-forth of around 0.050 inch
and without a dial indicator and magnetic base I cannot
determine if there is any run-out: I can't feel any, but there
might be a couple of thou. I can see the oil film bulge when I
rock the shaft left and right in the bronze sleeve.
Grainger says that the motor can run in ambient temperature
up to 104 F, and that's what the coil says. I thought it meant
the operating temperature of the motor, but after 20 minutes the frame
of the motor is way, way hotter than 104 degrees.
There are no ground-down wear spots on the armature or in the
shell. The copper pole windings look intact, and the laminations
are welded on the periphery of the stack in six places that I can see.
There's no discoloration of the nylon coil form and the armature spins
freely when turned by hand, with no rough spots felt.
In other words, the motor looks okay, feels okay, but just runs
extremely hot. Couple this with the fact of the motor failing to start
when the amp is turned on, sometimes, not always, and it just seems to
be a defective blower. Grainger wants about 40 bucks, shipped, for the
whole shebang
and I really don't feel like bothering Pat Stein at Commander Tech so
I'll
probably order up another one and scrap this piece.
Thanks for the tips on S-P motors.
Hal Mandel
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