Help me find the right starting capacitor

[jives]

Electrical is not my thing, so looking for as much help as I can.

My mid -60s Delta Rockwell drill press, model 15-665, began starting very slow, taking a few seconds after the switch turn on, then taking a few more seconds to get up to speed. Then last week it failed to turn on at all. No noticeable hum or indications of trying to start. I have inspected some visible wiring, including the switch and junction box, and all seems well. My DMM is in my office and I repeatedly fail to bring it home. . .

My reading of this problem hints that it could be the starting capacitor, and it seems like spending $10 is a good investment. But, trying to find the correct one eludes me, so I'm seeking your help. Here is the relevant info.

Motor: Marathon 62-011, frame 65-5, 3/4 hp, dual voltage 115/230 (11.2/5.6 Amps), type SCS, class B.
Capacitor: STM model 4207 (I guess that is the model?), 161-180 MFD.

Can someone lead me to a suitable capacitor?
Thanks.

 

[Terry D]

Post a picture of the capacitor. If it fits under a cover, you will need the same physical size

If you have a motor shop in town, they could probably test it for you and have one.

 

[Dumber than lumber]

Do you have the owners manual?
The vintagemachinery.org
website would be a likely source of help.
Free manual is going to make that $10 go farther!!

 

[jives]

I'll need to wait until I get home to post a pic and get dimensions. As for a manual, I do have a couple from Vintage Machinery, but they don't provide motor specific parts diagrams, and neither can I find a parts diagram for the Marathon motor -- not even on the Marathon website.

The closest electric motor repair shops are in neighboring towns of 45-60 minutes away.

 

[marinusdees]

If it doesn't hum when you turn it on, likely not the cap. The run winding is in the circuit when you flip the switch and will hum.

 

[exmaxima1]

If it doesn't hum when you turn it on, likely not the cap. The run winding is in the circuit when you flip the switch and will hum.

Good point. If no noise it is very possibly the power switch. Most of those old machines employed a double-pole switch that interupts both the white and black wires. If the contacts on one pole go bad you lose the power to the motor. Simple test is to bypass the switch and plug the motor directly into the power.

When I wire a machine that runs on 120vac I never switch the white wire (neutral). And if the switch is a double pole I wire both poles in parallel to double the current capacity of the switch contacts.

 

[jives]

First thing I did was remove the switch. . .then found out my DMM is at work, not home. I reckon I can just use a jumper to bypass. . .did not think of that!

Pics of the capacitor and the motor information plate. Capacitor is about 4" long and 1.5" in diameter.

Good point. If no noise it is very possibly the power switch. Most of those old machines employed a double-pole switch that interupts both the white and black wires. If the contacts on one pole go bad you lose the power to the motor. Simple test is to bypass the switch and plug the motor directly into the power.

When I wire a machine that runs on 120vac I never switch the white wire (neutral). And if the switch is a double pole I wire both poles in parallel to double the current capacity of the switch contacts.

 

[jives]

So, a final update. Received no response from Marathon electric regarding a capacitor. In the meantime I did blasts of electrical cleaner on all accessible contacts -- capacitor, switch, and junction box. For some reason it now works. It still takes about 2-3 s after pushing the ON button for the motor to start, but it does.

 

[Meursault74]

did you check the capitor with the DMM to see if it is within the ratings? it may be a little weak. discharge before checking.

These would likely fit the bill

https://www.grainger.com/category/m...itor+Type|Motor+Start+Capacitor&filters=attrs