Shopsmith Forums

So, with the help from JPG I was able to get my Mark VII back up and running, but now I have a different problem. It turns on just fine, but when I turn it off I get a clicking sound. It's almost a rattle sound. It does it in both directions. I did a little searching and others have mentioned the relay resetting for the next use, but this isn't just a single click. This is more like a baseball card in the spokes of a bike sound. It lasts for about 1-2 seconds. It makes the sound whether its belt is on, or off.

Any thoughts?

n240sxle91 wrote:So, with the help from JPG I was able to get my Mark VII back up and running, but now I have a different problem. It turns on just fine, but when I turn it off I get a clicking sound. It's almost a rattle sound. It does it in both directions. I did a little searching and others have mentioned the relay resetting for the next use, but this isn't just a single click. This is more like a baseball card in the spokes of a bike sound. It lasts for about 1-2 seconds. It makes the sound whether its belt is on, or off.

Any thoughts?

This is a guess, but I would say it is the relay chattering.

The cause could be interesting.

"The cause could be interesting" doesn't have a warm and fuzzy feeling to me.

Do you think the switch is causing the problem? Maybe it's shorting a little between Forward to Stop, and Reverse to Stop? I guess I could drop the motor out again and try the other switch...sigh. lol

n240sxle91 wrote:"The cause could be interesting" doesn't have a warm and fuzzy feeling to me.

Do you think the switch is causing the problem? Maybe it's shorting a little between Forward to Stop, and Reverse to Stop? I guess I could drop the motor out again and try the other switch...sigh. lol

No I do not think it is a 'problem'. More likely the relay has insufficient hysteresis when 'dropping' and reconnecting the capacitor etc..

I think leaving it alone is the best 'action' at this point.

The relay is 'picked' by the generation of voltage in the start winding as a result of the motor 'running'.

As the motor coasts there is a lot of stuff going on as it slows down. Collapsing magnetic fields and coils within them. 'Normally' the relay does not drop(close it's contacts) until the voltage generated by the start winding decreases lower than the relay minimum hold current. It may be that the relay is dropping too soon and the reconnecting of the contacts allows the run winding to induce current into the start circuit and cause the relay to 'repick'. Coils, capacitor, collapsing magnetic fields all interacting. Add a tired start relay(contact wear, pivot wear, contact gap changing, return spring weak . . .

If I were to suggest doing 'something' it would be to open up the relay and increase the return spring tension and make sure the contacts do not have a stalactite/mite.

I'll take your advice and leave it alone. I'll reassess if it gets worse, or fails.

Thanks again!