Vintage Delta Start Capacitor Problems.

[WD]

My vintage 1HP Delta Drill Press was working normally until last week it will not rotate but hums when I turned on the switch on. I removed the motor from the DP and powered up. It still will not rotate but starts to hum again. I rotate the pulley manually, it begins to rotate and speed up normally and the humming stop. I switch off the motor, before it stops completely I switch the motor on and it speeds up normally. I did another test: I turn the switch on, as it starts humming, than I rotate opposite direction, it speeds up and again it stops humming. Can I assume the start capacitor is bad? If, so where can, I buy a replacement. The Capacitor is an old one; Manufacture Name": SF??? MIKE" Type H, 210 259 MFD. 115VAC"

Thanks for your help.

[Tom Veatch]

Check the yellow pages for any motor repair shop in your area. You need to match the MFD and voltage ratings of the capacitor for performance reasons and the physical size for obvious reasons, so I'd advise taking the old cap with you when you go. Note that the voltage rating on the replacement can be higher than the original, but should not be lower.

You could also do a Google search for online sources:

If the link below is inoperative, do a search on (without the quotes) "motor start capacitor" and click on the "shopping" link.

's one that seems to be compatible with the electrical characteristics of your old capacitor, don't know about the physical size.

Veatch Wichita, KS USA

[Ignoramus6193]

Yes.

You need to buy a replacement start capacitor of similar capacity. A few bucks plus shipping. They are plentiful, see McMaster catalog page

925, for example. Item 7245K17 should work.

[WD]

search in the Internet and could not find an exact specification as marked on the old capacitor. Yellow page here in the SF Bay areas are practically useless that is why I posted here looking for help. The above link still does not give me the detail I need to buy the "exact or acceptable" capacitor. I hate to burn up the motor since I took so much effort to moved it two thousand miles away.

Thanks

[WD]

Thanks for your confirmation. Before I removed the motor from the DP I suspect either, the bearing or carbon brush was bad. As I rotated the pulley it rotated freely. I knew immediately it was the motor's start capacitor. I wish I had tested my lightly used, new 8" jointer's motor in KC before I moved. It had the same symptom. I sold the jointer for a song, and the buyer insisted I gave him the old motor as the new motor (I kept the new Baldor motor). I bought with the incorrect RPM. Thinking back, the buyer must be thinking how stupid I was.

I should have thought of McMaster before I posted here. However, I would like to know how do you buy from McMaster? They need company names etc, and I am buying for myself? I went to page 925 in McMaster, but no part 7245K17.

Thanks for your help, any other source with a correct capacitor?

[dpb]

WD wrote: ...

In a place as large as the Bay area, there are bound to be a zillion local motor repair shops that can supply your needs...

--

[N Hurst]

Just make something up. Or you can do what I did and put in what I will call my company if I ever decide to start one. I've bought from them a number of times and they've shipped straight to my house, no problems.

The only thing I don't like about their setup is that they don't tell you shipping up front, so you have to check the invoice. It's very reasonable, though. They're not the kind of company that will charge you $10 to ship a $2, if it doesn't actually cost $10 to ship it.

-Nathan

[Ignoramus15296]

I have a corporation, so I did not have to make anything up, but I would go the above suggested route. Their shipping is very much on the low side.

[Tom Veatch]

Go to

side of the page, enter "capacitor" in the search box

Third one down in the "AC Motor Start Capacitors", "110-125 VAC Capicitors" is part number 7245K112.

The electrical characteristics are correct for use as a replacement for your old capacitor, "Type H, 210 259 MFD. 115VAC". Whether the physical dimensions are correct is another question. If it will fit within the "bump" on the motor, go for it.

I've ordered from McMaster-Carr many times. As I recall, the "Company Name" field is not a required field, so if you don't want to make up a company name, just do as I do and leave it blank. They aren't like Grainger which does require a business name.

Tom Veatch Wichita, KS USA

[Lew Hodgett]

Two (2) possibilities.

1) Bad start capacitor.

2) Bad centrifugal switch.

Grainger can do a match up for a replacement capacitor.

Replace cap, if that doesn't solve problem, head to a motor repair shop.

Replacing a switch is a total PITA.

My guess is you will spend 60%-70% of new motor cost to make repairs with makes which makes repair a tough call.

YMMV

Lew

[stu]

As a journeyman electrician and a electronics technologist. " dead cap" or "busted centriflucle switch" no....big.......deal .... take cap and /or motor to any electrical parts dealer... get off the shelf.

Stu

[WD]

Thanks Lew, we have already established it is the start capacitor that is bad. I will attempt to buy it from McMaster-Carr. Thanks again

>

[Frank Boettcher]

And how did you determine this?

More often than not it is the centrifigual switch. May have dust in the contacts. Supposed to be a rubber boot that makes it dust proof, but, depending on the origin of the motor, maybe bad.

Does what you describe. Does not let the start circuit pull in. Contacts are supposed to close when the RPM's run down, but dust prohibits. When you spin it your are doing the same thing as the start circuit does, that is, starting the motor.

Frank

[Tom Veatch]

I've not witnessed a large majority of all motor failures of this type, so I'm not qualified to dispute that statement. But I can say that I have experienced two motor failures that presented the reported symptoms. In both cases, the failure was due to a leaking and failed capacitor. The switch in both cases was defect free. But, perhaps my experience is atypical.

Tom Veatch Wichita, KS USA

[Ignoramus21403]

I had the same experience.

To test for centrifugal switch, disconnect starting capacitor and measure voltage on capacitor leads during startup. (briefly, so as to not smoke the motor). No voltage means bad centrifugal switch.

[EXT]

Before you go purchasing a capacitor, if you are comfortable opening up motors, disassemble it and check out the starting switch, it may be stuck in the open position. The mechanism may need cleaning and lubricating so that it operates smoothly. It should be closed when stopped, and when power is applied the motor should start with the starting switch opening as it approaches operating speed.

[Frank Boettcher]

My experience may be slanted towards the difficulty in getting a true dustproof switch in a motor that is truly going to be in a very dusty environment.

It is a problem that had more warranty action.

However, you may be right in that if a switch is well designed and well made, gone through many cycles then failure of the cap may be just as prevelant.

Frank

[Lew Hodgett]

When you open up a motor, you are almost guaranteed to "brinell" the ball bearings getting the motor open which is why most motor shops replace the bearings when they open a motor.

Unless you have an arbor press, and the knowledge how to reassemble a motor so you don't "brinell" the new bearings during assembly, opening up a motor is to be avoided by the amatuer.

Lew

[Doug S]

Take it from an electric motor repairman - disconnect the capacitor and short the two wires together. If the capacitor is bad, the motor will start (it may start slowly, but it will start). If the motor still won't start, the problem is with the starting switch inside the motor.

If the capacitor is bad, you can replace it with anyth>

[WD]

Did exactly what you suggested. Yes, it start. I knew it was the capacitor, cuz the switch was solid and sound. Thanks.

The motor is 1HP (original Delta), Type H 216 - 259 MFD 115 VAC. From McMaster (Carr page 925) :

PN# 7245K114 AC Motor-Start Capacitor 340-552 Rating, 1-7/16" Case Diameter,

110-125 VAC PN# 7245K112 AC Motor-Start Capacitor 216-389 Rating, 1-7/16" Case Diameter, 110-125 VAC

Look like PN# 7245K112 closest to my original capacity, what say you?

Thanks again.