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humming noise coming from my delta unisaw when the power is off

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Forum topic by dardwood posted 11-14-2012 04:36 PM 1171 views 0 times favorited 12 replies Add to Favorites Watch
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dardwood

4 posts in 1201 days


11-14-2012 04:36 PM

I recently purchased a used delta unisaw. After about a month there is a humming noise coming from the little electrical
box when the power is off. The saw is working fine but the noise is has me suspect. Has anyone experienced this? What
could be the problem? Thanks guys.

dardwood


12 replies so far

View Tedstor's profile

Tedstor

1505 posts in 1380 days


#1 posted 11-14-2012 04:48 PM

An energized capacitor? For kicks, unplug the machine and flip the on switch. That should (in my shaky theory) discahrge the capacitor.See if the hum stops. WOn’t fix anything, but it might narrow down the possibilities. Might signal the beginning of the end for the capacitor. Good news is that a new one can be had for a few bucks.

Oh, and if the hum stops upon unplugging the saw, the switch will be the number one suspect.

View Cosmicsniper's profile

Cosmicsniper

2199 posts in 1905 days


#2 posted 11-14-2012 04:59 PM

Unisaws never break down. Must be the user. ;)

-- jay, www.allaboutastro.com

View RussellAP's profile

RussellAP

2966 posts in 1033 days


#3 posted 11-14-2012 05:01 PM

You may also find a relay that is energized by design which is buzzing slightly. If that’s the case, no problem.

-- A positive attitude will take you much further than positive thinking ever will.

View RussellAP's profile

RussellAP

2966 posts in 1033 days


#4 posted 11-14-2012 05:03 PM

Tedstor, never seen a cap make noise unless it’s blowing up or discharging and I don’t think that saw would hold a charge unless the diode is bad in which case there still would be no noise.

-- A positive attitude will take you much further than positive thinking ever will.

View Paul Miller's profile

Paul Miller

32 posts in 2200 days


#5 posted 11-14-2012 05:21 PM

My Dad bought his Unisaw new in the 80’s, and the electrical box (not the on/off switch) has hummed from day one. I always thought it was just the nature of the magnetic switch. He always unplugs it when not in use. Is there really a malfunction here?

View knotscott's profile

knotscott

5601 posts in 2122 days


#6 posted 11-14-2012 05:43 PM

Sometimes I get complaints about my humming in the shop, but I find it relaxing so I do it anyway! ;-)

-- Happiness is like wetting your pants...everyone can see it, but only you can feel the warmth....

View EEngineer's profile

EEngineer

906 posts in 2360 days


#7 posted 11-14-2012 05:54 PM

The magnetic switch on these saws has a 24V transformer. It drives the main contactor that supplies power to the motor. The humming you hear is most likely the core laminations vibrating at 60 Hz.

-- "Find out what you cannot do and then go do it!"

View knotscott's profile

knotscott

5601 posts in 2122 days


#8 posted 11-14-2012 05:54 PM

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Miss Zabrina – Would like to hear some of my humming?

-- Happiness is like wetting your pants...everyone can see it, but only you can feel the warmth....

View Dennisgrosen's profile

Dennisgrosen

10850 posts in 1862 days


#9 posted 11-14-2012 06:03 PM

and I just got a pm from her
I will thank her with a spamflag :-))

View REO's profile

REO

665 posts in 821 days


#10 posted 11-14-2012 08:48 PM

DoubleE nailed it. Xformer 60hz buzz

View toolie's profile

toolie

1773 posts in 1375 days


#11 posted 11-14-2012 09:02 PM

+1 for eengineer. the unisaw i just sold, which had a magnetic starter, hummed the first, and every time, i plugged it in. a little unnerving the first time it happens. on the plus side, if there’s a loss of power during operation, i’ll bet the saw won’t restart upon power restoration until the “start” button is pushed. nice little safety feature.

-- there's a solution to every problem.......you just have to be willing to find it.

View Howie's profile

Howie

2656 posts in 1670 days


#12 posted 11-14-2012 09:39 PM

My thoughts are that it’s actually an explosive device with a timer. Therefore you should ship it to me immediately for deactivation…....disclaimer…..I know nothing about electricity.

-- Life is good.

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