Sparks on Fwd/Rev switch contacts

[MobileSawMilSlo]

Hi guys

Today I was cleaning my LT20 and I removed the control panel to dust of sawdust and lubricate contacts of switches.

I noticed that when I use feed switch for forward position everything is OK, but when I use it backward there is big spark on one of the Fwd/Rev switch contact.

I regularly (every 50 hours) lubricate switch contacts so this should not be the problem.

Searching over FF I found out, that this could be the fact that:

1) A diode is bad and big current goes over the switch
2) Motor brushes are warned out and use too much current

Tomorrow I will test diode with a digital multimeter and hope to see what is wrong.

Nevertheless, do you maybe know how "strong" diode should be if I would buy it the local electronic store? And how often (how many hours) do you replace brushes at motors?

Thank you for now.

[Kbeitz]

A clamping diode is made to stop sparking. It stops ESD events.and back feed from the motor.

[MobileSawMilSlo]

Thank you for replay ... I will order a new one.  

I think that this one is right, isn't it? If I will not get it at WM seller can I replace with some other with the same specification (what kind?)?

[Kbeitz]

I don't think you can use just any diode. I think it needs to be a zener. Better buy the right one.

[sparks]

The arcing is normal. The contact grease is used to minimize the burning on the fingers. The fingers do not touch at exactly the same time so an arc will occur.

[Jeff]

My LT30 has been arcing for 32 years.  Sparks is the man. You won't get a better answer from any other source than from him.

[slider]

Good call on that Jeff . He is the man at Indy .