Electrical help on bench sander

[augerpro]

I've been looking for a bench sander that isn't junk but isn't terribly expensive either. Craigslist has some older USA made stuff, but nothing really compact that can be used on the rotating bench I'm thinking of building. Most <$150 seem to be rebadged versions of the same one, with Wen being the most popular version. Then I came across this Porter Cable PCB420SA: https://www.lowes.com/pd/PORTER-CABL...Sander/3163789. Seems to be an upgrade in power and direct drive, but still a victim of Chinafication with some known issues. I think I can resolve some of these issues with mods. One issue is the motor burning up which some attribute to drag or a capacitor issue. For the drag I'm removing the dust collection impeller and just attaching my own DC to the port. Regarding the capacitors I really have no idea what I'm doing other than wanting to replace in-kind with quality (Japanese?) versions from Digikey or Mouser. Here are some pics to give you an idea what is going on:

[JonMarsh]

Those are fairly specialized kinds of capacitors- particularly because of the high RMS currents they must handle in the motor application...

You may have trouble finding equivalents from Digikey or Mouser- their focus is more general purpose electronics, and capacitors as used for power supplies. Just note that you don't see much in the way of speaker crossover capacitors at those distributors. Specialized applications seem to tend to have their own distribution channels.

The capacitors markings give good clues for how to look- given these are basically all motor start capacitors.

One link from IEC 60652-2...

https://webstore.iec.ch/publication/1156

Google is your friend... sometimes. :W

[augerpro]

So the Exxxxxx number is the relevant spec (other than the basics of course)?

[JonMarsh]

Yup. Application type, sometimes ratings too.

[augerpro]

You're right these are tough to match. But I think I've waded through Mouser and found some, whether they are better or not is a different story.

Regarding the white "motor run" capacitor, I've found these: https://www.mouser.com/ProductDetail...ngPgn4irfsw%3d and https://www.mouser.com/ProductDetail...ReMknfQRF8o%3d Both have a Class A lifespan rating, which I'm using as a proxy for quality. Both are higher VAC than mine, but as I understand it, that is only a good thing.

The only match for the grey "start" cap is this: https://www.mouser.com/ProductDetail...2BqdFF2w%3d%3d with a lower lifespan rating.

Am I on the right track, or just going to blow myself up?

[augerpro]

60000 hour at rated VAC: https://www.digikey.com/product-deta...803-ND/2231531

[sdl2112]

Do you have a multimeter that can measure capacitance? I would check that first. The dates on those are so new I would hate for you to spend money on different ones if those measure ok.

The Exxxxxx number is a UL file number for component recognition, it can be looked up at database.ul.com

The gray cap is an electrolytic, the white is a film type.
http://database.ul.com/cgi-bin/XYV/t...762&sequence=1

http://database.ul.com/cgi-bin/XYV/t...076&sequence=1

Data sheets;
http://en.cnsofo.com/products_detail/productId=48.html

http://www.anhuisafe.com/Show.asp?id=196

You are on the right track. The 100uf you link is certainly an upgrade as it’s a film vs electrolytic the others with a higher voltage are also likely better.

[augerpro]

Reviews seem to show a number of complaints about caps burning out, that is the main reason I'm looking to replace them before they fry and damage something else, like the motor. Any thoughts on the Kemet vs. TDK?

[sdl2112]

I think either one is fine.

[augerpro]

Well I installed the 20uf TDK and 100uf Kemet caps tonight. Did some other mods and checks, fired it up and it ran fine. We'll see how it handles a load when I get my bench built.