help with wiring problem on wide belt sander

[Kelvin]

Howdy all,
I've got a sunhill import open end 15" wide belt sander.  Works wonders over the old 24" twin drum i had, but the feed motor quit on me and i'm not sure where the weak link might be.  Its a three phase machine i run off converter and the main motor powers up so my connections to there are fine (main sanding motor on sander)  The feed motor is single phase and when i push the button on the outside i see the contactor engage inside the control panel and a little arc on one side of it, but not the other.  Is this contactor a weak link?  I've jiggeled every wire going in and out with no luck.  Where to look.
Another question the panel says "for single phase motor wire here.. for 3 phase wire here..."  I'd like to switch this motor out with a single phase but thought the wiring would have to be redone inside.  This machine comes in both single and 3 phase.  Think i can just switch over and not have to change anything else inside?
Any ideas where to check, what to check would be helpful.
Thanks
kelvin

[logwalker]

Star probing with a multi-meter at the switch and see if you are getting two legs of voltage out of it. If you are then it is likely the motor. Is the feed motor a capacitor start?

Joe

[Den Socling]

A starter is a contactor with an overload. Since it is energizing, nothing would be shorted. I would use a multimeter in the junction box on the motor and, with power off, check continuity back to the starter. Does the motor have a thermal overload? It would be kind of obvious unless the motor is covered up.

Do you want to change your sanding motor from 3 phase to single phase? You might need to change wire size and you would definitely need to change the overloads (fuse and/or starter).

[solidwoods]

If you can had turn the feed motor and it turns feed system look at electrical.
Normally can the feed motor be turned on only (sans sander head)?
Unplug the machine and check motor leads for grounded (isolate the motor lead don't check them as they are hooked to the starter and a short that direction would make a indication of a short)?

Wiring the 110 feed motor from another source will prove the feed motor and feed system is good.  Then look backwards starting at the wire to the feed motor for short then  proper voltage.

Check normal and emergency shut off switches also.

Check all grounds as you go through the electric system.
jim

[low_48]

I think  most of those contactors are like the old ignition points in a car distributor. You might be able to take it apart and polish the contact points with some emery cloth to get it going again. Sorry, no help with the single/three phase question.

[Kelvin]

Howdy all,
Okay, thanks for the ideas.  I'll check them out.  The feed is seperate from sander head.  I'll see if i can turn it, and try wire it seperately and see if it runs.
Kelvin

[Den Socling]

Kelvin,

When you push the start button and you see the contacts on the starter close, does the motor move briefly?

Do the contacts stay closed when you hold the start button down.

This is kind of strange. The fact that the starter energizes means that the safeties are closed and there is continuity through the starter coil. The fact that you see an arc means that you have continuity through the motor. Have you tried saying "hey dummy! There is no reason for you not to work!" 
Den