Search found 63 matches

by johnm
Wed Apr 27, 2016 11:07 am
Forum: Maintenance and Repair
Topic: The usual noobie mistake -help please
Replies: 49
Views: 10115

Re: The usual noobie mistake -help please

A weak capacitor? Is that a capacitor that either does not take a charge or does not hold a charge? The electrolyte inside dries out (due to heat, age). It basically just means that the capacitance value drops outside of the rated value on the label. Since these are AC capacitors, they don't really...
by johnm
Wed Apr 27, 2016 10:37 am
Forum: Maintenance and Repair
Topic: The usual noobie mistake -help please
Replies: 49
Views: 10115

Re: The usual noobie mistake -help please

What happens if, due to a malfunction, the motor remains in the start mode? In this configuration, both the start winding and the run winding are drawing current. Does this create an overload condition? By design, at about 75% of run speed, the start circuit should be disconnected. If it does not d...
by johnm
Tue Apr 26, 2016 10:54 pm
Forum: Maintenance and Repair
Topic: The usual noobie mistake -help please
Replies: 49
Views: 10115

Re: The usual noobie mistake -help please

It sounds like the motor is not starting properly under load, which points to: a) the start switch is bad or not making contact, b) the starting capacitor is bad or weak, or c) the start winding is open. If the start winding doesn't kick in, the motor wont develop enough torque under load and will s...
by johnm
Wed Jun 08, 2011 2:54 pm
Forum: Maintenance and Repair
Topic: Repair Craftsman electronic radial arm saw?
Replies: 75
Views: 125922

No joke!!! Those wires are barely over the thickness of a human hair. I couldn't even see them without the magnifier. A motor shop might be able to help. The question is why they burned out like that. If AC is applied rather than DC to the input, the motor wouldn't turn and the current through it m...
by johnm
Wed Jun 08, 2011 2:10 pm
Forum: Maintenance and Repair
Topic: Repair Craftsman electronic radial arm saw?
Replies: 75
Views: 125922

OK. After a few more tests and a major discovery. First when trying to get an ohm reading on the power input points]13310[/ATTACH] Put one lead of the multimeter on the segment with the burnt spot and the other on another segment and see what you get. If the solder is just loose, you might be able ...
by johnm
Wed Jun 08, 2011 1:10 pm
Forum: Maintenance and Repair
Topic: Repair Craftsman electronic radial arm saw?
Replies: 75
Views: 125922

Keith, you were close, but you got two diodes reversed. [ATTACH]13276[/ATTACH] The pink? thing across the armature is probably a capacitor, but may be a resistor. Missing is the metallic object mentioned before.????? I think I've sorted this schematic out and how the motor is supposed to operate. F...
by johnm
Wed Jun 08, 2011 11:24 am
Forum: Maintenance and Repair
Topic: Repair Craftsman electronic radial arm saw?
Replies: 75
Views: 125922

[quote="tdubnik"]John, Thanks for the post. The motor does turn easily by hand. It seems like this is the place to start and the first thing I need to determine is whether the motor actually works. My first question would be how do I do that? I have a multimeter and I can take measurements...
by johnm
Wed Jun 08, 2011 10:29 am
Forum: Maintenance and Repair
Topic: Repair Craftsman electronic radial arm saw?
Replies: 75
Views: 125922

I just caught up with this thread... It seems that if you measure voltage on the motor brushes and it is wired like you show in the schematic, then it ought to turn. Can you turn it by hand? Make sure it is not binding. If the armature winding (the part the brushes connect to) is open circuit, then ...
by johnm
Fri Jan 29, 2010 2:42 pm
Forum: Community
Topic: Today's SCORE!!
Replies: 59
Views: 14017

That looks like a nice old Dewalt MBF (or similar). First thing you should do is visit the Mr. Sawdust site and order his book (written by the late William Kunkel). With the cast iron arm, those things are really precise. Kunkel's book will tell you how to build a stable table and do a precise align...
by johnm
Fri Oct 23, 2009 11:48 am
Forum: Maintenance and Repair
Topic: Shopsmith Mark 5 - GE 3/4 HP Maintenance Tips
Replies: 5
Views: 21651

[quote="shotrabbit"]I dropped my motor and smashed the relay casing but the works seems intact but some parts bent. I can put the box together but I need to reposition some of the relay parts. I need to repair this one or buy a new one. I motor is fine and I cannot spend $300.] Here you go...