When attempting to power on the Sears RAS (circa 1977) set for 110V, it
instantly throws the 20 amp dedicated breaker with no rotation or hum
at all. The saw was working fine moments before the failure. I was
just doing a couple of crosscuts (i.e.no extended hard cuts). Based
on previous posts, here's what I've done so far:
1) tried the saw on another 20 amp dedicated breaker, same results (no
extension cords in use)
2) took off the case, cleaned all saw dust out with a compressor
3) "sniffed" for burnt windings (no smell at all)
4) inspected all internal and external wires for nicks, scraps,
pinches, etc, (wires look good)
5) Did a basic VOM test on the starting capacitor (seems to check out)
6) Reviewed the "breaking/starter" switch, points are a bit rough and
I do see an arc at this point during testing. Is this arcing a symptom
of bad windings, etc. or could the arcing itself be the source of thown
Any help greatly appreciated,
PS..First post...Hope I followed proper protocol :)
What does "seems to check out" mean? What readings did you get?
With the capacitor disconnected and with the meter set to the highest
OHMS setting you should see a small kick of the needle and the reading
should then go to infinity as the capacitor charges. If you get a
resistance reading other than infinity once the capacitor is charged the
capacitor is shorted.
Using your cap test with the VOM set at 2000k, i get a digital spike of
about 1000 but it never returned to infinity or for that matter started
to approach infinity. One other curious thing I failed to mention, the
saw will trip the breaker even without the power switch on....
Thnanks for the reply....
If the saw trips the breaker without it's power switch on (like when you
plug it in with the power switch in the off position), then the problem is
NOT the motor. It's a short somewhere in the line cord, plug, or wiring
leading to the switch.
< email@example.com> wrote in message
I would have agreed with the wire/switch short conclusion, but here is
a test I did this morning. I disconnected the main WHITE and BLACK
wire from the wiring connector block to isolate the 110V cord and user
power switch from the motor. There is no continuity between the WHITE
at the terminal block end and the BLACK at the plug end (and vice
versa) regardless of the position of the user power switch. Doesn't
this rule out a short in the 100v wiring and/or power switch?
What brand of receptical are you pluging it into? I had a similar
problen several years ago after some ham handed carpenters doing some
work at my house yanked theirplugs out at an angle and broke the
plastic insulating material. When you then tried to plug another cord
into the recpt. it would short and trip the breaker. The recpt's were
With the help of this usenet group and additional ideas, I have
identified the problem. It indeed was a short to ground. There is
"start switch relay" that had plastic standoffs on both sides of the
relay tab as an insulation off of the frame (ground). Over the last 27
years, heat had slowly melted the 1/8" thick plastic tab to less than
1/16" of an inch until the relay tab actually fused to bracket attached
to frame ground. Voila, short! I've identified the part at a Sears
webpage. Hope to order it tomorrow, but if it's unavailable I'll
fabricate small teflon insulation "dots" and glue them to the existing
Thank you all for the guidance and ideas,
MOP CAP wrote:
Just a comment, and not relevant to your problem, but if you are in the US
you might want to take a look at http://www.radialarmsawrecall.com /. If
your saw is affected it gets you a new blade guard and table, for free.
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