He was advised that it was a short. You are correct that the correct
condition condition description is OPEN Circuit. If the fields happen to
be in parallel then that would be where I would start looking.
On 02/15/2013 01:04 PM, Jim Nichol wrote:
Al didn't say you had a "short". He said you had an "open". They are opposites of each
other. He only mentioned "shorted turns" to imply that they are NOT likely to be the problem.
A broken wire is an "open", resulting in zero current. A "short" is two wires touching each other, causing the current
to take a shorter path than intended. In a lamp cord a short would blow a fuse, whereas an "open" would prevent current from
flowing. I recommend not saying "short" when you mean "open" (though many electrical novices do). If you said you
thought "the motor has a short" at a repair shop, it would mark you as unknowledgeable, maybe setting yourself up to be ripped
off.
The symptom of an "open" in your motor would be that nothing happens at all. On the
other hand, saying the motor has a short (or more specifically "shorted turns") means
that a few of the loops of wire in the coils are shorted together, causing the current to bypass
them. This would lower the overall resistance of the coils, thus increasing the current. The motor
would still run, but would have less magnetic torque (because some of the turns of wire are not
carrying current), and the remaining turns would get hot.
Sorry for the lecture, but as an electrical engineer, this is one of my pet
peeves.
Jim
On Feb 15, 2013, at 8:53 AM, Vinyl Visions<vinyl.visi...@live.com> wrote:
Al,Thanks for the reply. As you noted, I have been advised that it was a short
in the motor somewhere. The problem seems to be that this motor is wound for
three different types of power - AC/DC and maybe 220. So, either the shops
don't know what the problem is or they just don't want to mess with it... I'm
tending toward the latter, since the guys I sent it to are very knowledgeable.
There is a picture of the motor on our website: www.carolinaphonosociety.com
A shortcut to the pic is:
http://open1234.wix.com/camps-site/twilight-zone-2#!__fairy-phono-lampCurt
To: phono-l@oldcrank.org
From: clockworkh...@aol.com
Date: Fri, 15 Feb 2013 04:01:17 -0500
Subject: Re: [Phono-L] Turntable Motor Question
Induction motors that lack torque can usually be traced to an open field coil
or an open armature loop. A shorted turn will eat torque but the motor will
let you know by getting hot. How about a photo of the motor? Most good motor
shops can fix anything from fractional horsepower to 100 HP. Do you know of
a fan collector in your area? I have repaired fan motors that lost power and
have the same symptoms of your phonograph. These things are not rocket science.
Best wishes,
Al
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