I was using my Portal Cable quicksand orbital sander today and as I was sanding, the sander began to loose power, and it eventually stopped working. I had it hooked up to my shopvac during this time so it wasn't being clogged by dust. It went completely dead. I turned it on and off and it didn't turn on. I checked the power to see if a fuse had blown and when I turned the sander on, Upside down, it started and got the speed going, but when I turned it right side down it stopped. I started to take it apart but when I was trying to take the outside of the unit off, it was still connected to the bottom. I gave up to do a little more research on how to dissemble the unit. 

 

I am a bit perplexed on why the sander turned on when it was upside down. I was thinking perhaps a wire became loose. 

 

Any ideas why this could be happening?

 

Best regards, 

 

Ron 

It may be a frozen brush that wore enough to not make contact on the armature.  The armature may also be worn and when you turn it upside down the armature moves and makes contact with a good portion of the armature and runs.  Check the brushes when you get that far into it.  Just a guess.

Another possibility is a loose wire and when turned over makes contact.  Probably need top clean brushes and armature as Dan said also.

 

One more idea if this is the 333 there is a belt that controls the pad. The belt is under the pad. If the motor is spining but not the pad this may be the problem. Looked at the manual and there is no parts list for the inside.

Occasionally the bearing holding the pad on my electric sanders will seize up. I take them apart to get to the bearing and then not removing the rubber seals on either side force some oil into the balls and work it free then it will be good for a few more months of use. 

   I also have an electric angle grinder I have to hold the electric wire just right going into the housing and it will run.. A busted wire right at the entry point but this has been this way for many years and it is easier to hold the wire at that spot and make it work than take the time to fix it right....

  If it is a bearing shot just take that bearing to a place that sells bearings and they can match it up.

54 minutes ago, Smallpatch said:

but this has been this way for many years and it is easier to hold the wire at that spot and make it work than take the time to fix it right....

I have fixed several issues like this for friends over the years.  Not a hard job but does take some time and patience.

On 7/24/2019 at 11:31 AM, Gerald said:

Looked at the manual and there is no parts list for the inside.

There is a parts list on ereplacements, but a lot of them are listed as discontinued.

 

https://www.ereplacementparts.com/porter-cable-333-type-random-orbit-palm-sander-parts-c-129_1997_2004.html

Well, I went back to my shop and took everything out of it and got down to the motor. All of the bearings were okay, I guess you only been could have been the brushes or the motor, but every thing that I would need.....are no longer being made. Anyone want a Porter Cable paperweight? 

 

Thanks for everyone who posted, but it is beyond being able to repair. 

 

best regards, 

 

Ron

All to common when brands are acquired by other companies.  Porter Cable was acquire by Stanley Black&Decker then the product line was re-engineered to become a low-end tool (what I call Joe Garage, the kind of user that would use the tool a couple of times a year).

I don't know if it's true or not, but I heard a guy bought all the factory's parts for Delta power tools when they got acquired by SB&D.

That's one reason I've always shied away from Craftsman -- they frequently changed OEM du jour and parts became rare.