[CrBriggs87]

Hi there, apologies in advance if this is the wrong spot for this - VERY new here. I am trying to diagnose the problem with my motor. It runs but trips the breaker after 10 seconds. I have talked to electrical engineers, master electricians, so on and so forth. It has come down to the most likely cause being the capacitor or the starting circuit switch being stuck. It is a very old model and hard to find specifics on it.

Craftsman 3/4 hp capacitor motor. Ball bearing. 3450 RPM. 115 volts. 60 cycle. 9.3 amps. Model # 115 7167.

I have tried many different outlets, all 20 amp. Always with the same result. My biggest problem now is trying to figure out how to get into the solid metal casing. I have taken the 4 long bolts that run through out - taken the stand bolts and stand off. The plate that covers the two terminals off and disconnected both. There doesn't seem to be anything else holding them on. They spin but won't come off. Just hoping someone out there has run into this and could give me some advice. Thanks!!!

 

[knotscott]

A pic will answer a lot of questions....

 

[CrBriggs87]

Thanks for the quick reply. I managed to take a couple with the camera on the laptop, not the best but hopefully they help.

 

[Dave Paine]

Not easy to see the details not enough lighting.

Is it my eyes or am I not seeing the characteristic "bump" for the capacitor?

Could be an old motor. Perhaps the centrifugal switch is stuck.

Need to open the fan end of the motor to confirm the centrifugal switch is able to move freely.

Take a look at this thread.

http://www.woodworkingtalk.com/f12/repair-your-bandsaw-other-motor-crash-course-46405/

 

[CrBriggs87]

You are right, there is no "bump". I have heard that it could be the centrifugal switch but again, the main problem I am having is not being able to figure out how to get the metal casing off to access the fan end. Will check out the link! Thanks!

 

[CrBriggs87]

Just checked it out - seems like that could be the problem. As far as I understand it, that being stuck would still allow the motor to start but would be drawing too much and trip the breaker. Unfortunately, mine isn't so easy to take apart. I have not been able to find anything online showing the process of taking this exact model apart. I am about ready to just get a new motor! Lol

 

[Dave Paine]

You are right, there is no "bump". I have heard that it could be the centrifugal switch but again, the main problem I am having is not being able to figure out how to get the metal casing off to access the fan end. Will check out the link! Thanks!

Normally the screws are the full length of the motor, so a screw on one end and the nut on the other.

Once the screws are removed, need to tap the fan end with a rubber mallet. May need some rust penetrant in case there has been some rust over time.

 

[CrBriggs87]

Thank you my friend! You solved my problem in 1 hour. I have been struggling with this for days! My mother always told me not to force things but in this case it's what was needed!!! It is now apart and I can begin further troubleshooting! Thank you thank you thank you!

 

[Dave Paine]

Thank you my friend! You solved my problem in 1 hour. I have been struggling with this for days! My mother always told me not to force things but in this case it's what was needed!!! It is now apart and I can begin further troubleshooting! Thank you thank you thank you!

Terrific, happy to help. :thumbsup:

I also am careful about bashing things. Done my share of breaking things over the years.

Thanks for the update, good to know when a post or two helped.

 

[Chris Hillmann]

CrBriggs87, did you fix your motor? I have the same motor that I was given in pieces and I'm trying to clean it up and replace the capacitor before putting it all back together.

 

[Steve Neul]

It looks more like a repulsion motor to me. They wouldn't have a capacitor.

 

[TimPa]

the motor you have pictured does not look like a capacitor start motor.

a capacitor will not be inside a motor frame, they are externally mounted, typically on the motor. if no start cap, it is likely a split phase motor. an internal centrifugal switch will switch out the start windings after a certain rpm is reached.


not sure about the repulsion motor, steve. are they common?


woodworking motors often get dirty in there and need cleaned out occasionally. reach the switch and blow it out good with air, then test the switch, can spray contact cleaner on the contacts, may help.

 

[Steve Neul]

the motor you have pictured does not look like a capacitor start motor.

a capacitor will not be inside a motor frame, they are externally mounted, typically on the motor. if no start cap, it is likely a split phase motor. an internal centrifugal switch will switch out the start windings after a certain rpm is reached.


not sure about the repulsion motor, steve. are they common?


woodworking motors often get dirty in there and need cleaned out occasionally. reach the switch and blow it out good with air, then test the switch, can spray contact cleaner on the contacts, may help.

A repulsion motor is what they used commonly before the 1960's. I'm still using a repulsion motor which I took off my first table saw. It was also a sears saw which looked just like this one.

 

[TimPa]

the motor in the op pic looks to be that vintage alright.


will have to look it up... thanks.

 

[Chris Hillmann]

This motor does have a capacitor

The capacitor to this motor is a flat, cardboard cased, metal box located in the underside of the motor. I have been looking for an exact replacement and I'm not sure which MFD rating to go with since part of the numbers are rusted over. If somebody would be willing to snap a picture of the writing on the capacitor, I'd greatly appreciate it.

 

[TimPa]

nice find! it was beyond my knowledge!
did that wire break as you were removing? it needs to be soldered back on to the cap terminal.

it appears to be a start capacitor alright. if you have an ohmmeter, you can test the cap, it may be good. you will still want to check out the internal centrifugal switch.


if cap is bad -doubt you will find a square style, but maybe. you may have to convert to cylindrical style. you will need a _30-350 MFD and 125v rating.


you can exceed the 125v rating if needed. for capacitance, look for anything that has a range up to 350 micro farad. no polarity concerns when connecting.

 

[shoot summ]

The capacitor to this motor is a flat, cardboard cased, metal box located in the underside of the motor. I have been looking for an exact replacement and I'm not sure which MFD rating to go with since part of the numbers are rusted over. If somebody would be willing to snap a picture of the writing on the capacitor, I'd greatly appreciate it.

This, many of those older motors, with cast bases, had the cap there instead of externally.

 

[mikechell]

Looks like some serious corrosion going on there. I'd replace bearings while I had it apart. Clean the commutator strips and insulators ... replace brushes ... etc.
If you're reconditioning, don't just go half way!

 

[Chris Hillmann]

did that wire break as you were removing?

The wire was already broken and has green/blue corrosion on the end of it.

it appears to be a start capacitor alright. if you have an ohmmeter, you can test the cap, it may be good. you will still want to check out the internal centrifugal switch.

I most definitely want to replace the capacitor, and was hoping someone here would know which to choose, or even where to find these box type caps. As far as the centrifugal switch, mine was located opposite the fan end and I will be cleaning it up. I also want to replace any of the lead wires and will add pictures with more questions regarding those once I have them uploaded to my computer.

if cap is bad -doubt you will find a square style, but maybe. you may have to convert to cylindrical style. you will need a _30-350 MFD and 125v rating.

Any recommendations on the range? Could this be 230-350, 280-350, or 330-350?

 

[TimPa]

The wire was already broken and has green/blue corrosion on the end of it. this is likely why the cb was tripping




I most definitely want to replace the capacitor, and was hoping someone here would know which to choose, or even where to find these box type caps. As far as the centrifugal switch, mine was located opposite the fan end and I will be cleaning it up. I also want to replace any of the lead wires and will add pictures with more questions regarding those once I have them uploaded to my computer.





Any recommendations on the range? Could this be 230-350, 280-350, or 330-350? any one should work, just as long as the upper number is close to 350 mfd.

is there any other writing on the cap? good luck