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Forum topic by OnhillWW posted 10-04-2021 07:09 PM 436 views 0 times favorited 10 replies Add to Favorites Watch
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OnhillWW

319 posts in 2519 days


10-04-2021 07:09 PM

Hello, I am pretty good with house and ignition wiring but I have a sander issue that has me stumped and I hope that someone can shed some light on my situation. I have a Delta (31-050) 1” x 30” belt sander . It developed a bad bearing on a belt roller wheel so I took it apart and set it aside while I waited for replacement bearings to arrive – well I had 2 other sanders so completing the project was not a priority and it sat around for 2 years. Last week I decided to complete the repair and put her back into service. All went well however when I plugged it in the motor hummed with the switch in the OFF position and the sander ran well with it in the ON position. I checked the switch (an illuminated 2 position 3 prong switch) and it checked out to be OK but I ordered a new switch anyway, installed it and the same thing happened. So now I order a capacitor and swapped that out and still no fun in Mudville. The sander worked perfectly before I changed the two bearings (obviously not related to the problem); it sat for 2 years in a northern unheated shop before I completed the repair. Any and all thoughts are appreciated, thanks.

-- Cheap is expensive! - my Dad


10 replies so far

View Ruscal's profile

Ruscal

125 posts in 465 days


#1 posted 10-04-2021 07:28 PM

Did you try plugging it to a different circuit?

-- Have a hobby? You should have a business.

View TopamaxSurvivor's profile

TopamaxSurvivor

22834 posts in 4962 days


#2 posted 10-04-2021 11:27 PM

Obviously, the motor is getting connected to a low level of voltage somehow to make it hum, but I have no idea where it is. Probably a short circuit around the switch area would be my best guess. Good luck.

-- Bob in WW ~ "some old things are lovely, warm still with life ... of the forgotten men who made them." - D.H. Lawrence

View Richard Lee's profile

Richard Lee

445 posts in 2062 days


#3 posted 10-04-2021 11:40 PM

Sure sounds like a switch problem, did you double check the connections and if it was properly wired initially.

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OnhillWW

319 posts in 2519 days


#4 posted 10-05-2021 02:38 AM

Everything tells me it should be a switch as well. I actually got 5 new switches because that is the way they were sold. I tried 2 of them and it was the same problem. Maybe I need to try the other 3?

I did check the switch wiring against one of my other Delta sanders and it is exactly the same. Also I never opened the switch compartment until I encountered the problem and it worked fine before it was stored. I think I read that some motors have 2 types of windings inside. I have to wonder if there is some kind of short inside the motor.

-- Cheap is expensive! - my Dad

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TopamaxSurvivor

22834 posts in 4962 days


#5 posted 10-05-2021 03:18 AM

Do you know how to use an ohmmeter to see if the switch is open?

The diagram in the lower right shows it has start and run windings but no centrifugal switch. Motors with that switch are on equipment that needs higher starting torque such as pumps. If it had that switch it would not start if stuck open and blow your circuit breaker if it was stuck closed.

https://www.ereplacementparts.com/delta-31050-type-belt-sander-parts-c-3275_3512_13719.html

You could test is wiring connecting the neutral wire shown in the diagram as connected on the switch with a wire nut then use a regular light switch to see if you still get the humming sound.

The power causing that hum has to be through a very high resistance connection

-- Bob in WW ~ "some old things are lovely, warm still with life ... of the forgotten men who made them." - D.H. Lawrence

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TopamaxSurvivor

22834 posts in 4962 days


#6 posted 10-15-2021 06:52 PM

Did you find out why the motor was humming?

-- Bob in WW ~ "some old things are lovely, warm still with life ... of the forgotten men who made them." - D.H. Lawrence

View MrRon's profile

MrRon

6213 posts in 4530 days


#7 posted 10-16-2021 02:48 AM



Do you know how to use an ohmmeter to see if the switch is open?

The diagram in the lower right shows it has start and run windings but no centrifugal switch. Motors with that switch are on equipment that needs higher starting torque such as pumps. If it had that switch it would not start if stuck open and blow your circuit breaker if it was stuck closed.

https://www.ereplacementparts.com/delta-31050-type-belt-sander-parts-c-3275_3512_13719.html

You could test is wiring connecting the neutral wire shown in the diagram as connected on the switch with a wire nut then use a regular light switch to see if you still get the humming sound.

The power causing that hum has to be through a very high resistance connection

- TopamaxSurvivor

I looked at the parts list for the sander. They must be out of their minds on the cost of the available parts. A trip to ACE Hardware would replace all those fasteners for a few cents.

View OnhillWW's profile

OnhillWW

319 posts in 2519 days


#8 posted 10-16-2021 12:09 PM

TopamaxSurvivor,
I got waylaid onto a project and the weather has been unseasonably nice so I have directed my attention outside to the house and yard getting ready for the winter – I hate even writing that word. My plan is to spend Sunday in the shop, I will test the switch as you described, I appreciate your and everyone’s help. I will report back as soon as I know something.

-- Cheap is expensive! - my Dad

View Woodnmetal's profile

Woodnmetal

200 posts in 132 days


#9 posted 10-16-2021 02:55 PM

If you get back to it on Sunday,
I would check the ground wire before trying to fire it up again. Clean the ground really well, perhaps splice the wire back to see its condition and re-wire a new ground.
Just my suggestion. The hum in the off position is suspect of that IMO..

If you don’t have a multimeter. I would certainly invest in 1, they are very easy to figure out. It would pay for itself quickly in a case such as this, also save you some time, money and headache later down the road as well.

Sounds like you really want this tool back in service, so I hope it works out.

-- I haven't changed... but I know I'm not the same.

View TopamaxSurvivor's profile

TopamaxSurvivor

22834 posts in 4962 days


#10 posted 10-16-2021 07:50 PM



TopamaxSurvivor,
I got waylaid onto a project and the weather has been unseasonably nice so I have directed my attention outside to the house and yard getting ready for the winter – I hate even writing that word. My plan is to spend Sunday in the shop, I will test the switch as you described, I appreciate your and everyone s help. I will report back as soon as I know something.

- OnhillWW


Thanks, I’m probably too curious ;-) It is always a good idea to verify the ground. The most important part of electrical systems. Sort of like starting a car. You probably shouldn’t if the brakes aren’t working ;-)

I have a similar situation with a flashlight. It would not turn off. It only went between high and low. I checked the switch and it was not a 3 position with a dimmer, it is mechanical off and on. When I installed new batteries the light was off or on, no dimming. A month later, without being turned on, the batteries were dead ;-( This has to be some kind of high resistance failure of the switch. I haven’t tried to disassemble it yet because of a shoulder injury that has left me one-handed ;-((

-- Bob in WW ~ "some old things are lovely, warm still with life ... of the forgotten men who made them." - D.H. Lawrence

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