Unisaw starter problem

[art pfenn]

Hello all, I hope someone can help me solve my problem. I have an older Unisaw that has just started giving me a problem. When I push the start button either nothing happens or it starts. Sometimes it starts and then stops Sometimes I can keep it running by keeping my finger on the button. I took the cover off the and checked all the connections, I did the same for the push buttons but didn't find anything obvious. I checked and it has 220 going in to the box at L1 and L2 from there I have no idea how to trace the power. It is a single phase 3 hp motor and I believe that the starter is a model 52-704. I got the wiring diagram off the internet but can't find any trouble shooting information. I did find some information on this web site but couldn't follow some of the suggestions, I am attaching a picture of the inside of the box as well as the push buttons. There are a few wires in the push button box that aren't connected but they seem to be going to the light and have no effect on things.

[Larry Fox]

Whenever I have had the "it will start but won't stay running unless I hold the button in" problem with my 2005-ish single-phase Unisaw I turn the power off, remove the cover, blow it out with some compressed air and put it back together. Doesn't happen very often but seems to fix it every time it happens. Don't have a scientific explanation but I suspect dust on the contact surfaces or something similar.

[Joe Kieve]

+1 what Larry said. However, I'll add...unplug, make sure all screws are tight, then blow out contactors with compressed air.

joe

[art pfenn]

I'll give it a try. Wouldn't you know yesterday I had my smaller pancake compressor outside and opened the bleeder valve on the bottom so far that it shot out and was lost in the yard. My garage compressor is too big to move so I'll get a new valve today and blow the dust out. I did check all the connections and they were tight. When I called Delta they said it happens with age and I need a whole new starter.

[Charles Lent]

This sounds to me to be a problem with the normally closed contacts in the Stop button, but you may also have one or more loose connections in the wiring. Clean the Stop button contacts and tighten all of the wiring connections while making certain that each wire is being properly and completely held by the screw. From your description, my bet is on the Stop button contacts causing your problem, but it might be a good idea to clean the Start button contacts and the small relay contact on the side of the motor starter relay while you are in there. They are all part of the motor start/stop circuit.

Charley

[art pfenn]

Well I blew things out and still no luck. As far as the stop button contacts are you refering to the screw contacts? The contacts inside the start and stop buttons can't be accessed because of tyhe way the buttons are made.

[Joe Kieve]

Art... If blowing out didn't work, you might also try spraying some electrical contact cleaner on the contactors, then blow out again and make sure all is dry inside. Beyond that I'm at a loss. Had to replace my entire switch awhile back because of similar problems. Cost was, IIRC, $150 at Redmond in Newnan, GA.

Joe

[art pfenn]

When you say your entire switch do you mean the push buttons or the whole starter system?