I have an old VII model. I have used it in the past with no problems. The last couple times I tried to use it, it blew the breaker and the cord got hot. This was just when it was running without anything going on. I changed the plug to make sure it was getting good connection at the outlet.
I tried it again today and again it overheated and popped the breaker. It was in idle and was not even working. Again the cord was hot and there was smoke coming out of the headstock. I looked inside and the motor was too hot to keep my fingers on it.
I would have thought if the motor had shorted out it would not run at all after that. Could it just be a minor short that just causes the heat to build up?
Any advice?
Dale
Hot Motor
Moderator: admin
It may have a stuck centrifugal switch and is running on the start windings. Other things could be tight bearings or dirt in the windings and the inside not getting enough air flow. Don't run it any more until you get the motor completely checked. If you can open the motor and check the windings and you find that they have gotten black I would not hold out too much hope for the motor. Check the easy stuff first. About 95% of electric motors can be repaired if the windings are not burned.
Bill V
Bill V
chapter two
I just took the headstock apart. Just inside where the wire goes through the housing a previous owner had cut the wire for some reason and just hand twisted the wires back together and wrapped it all up in a ball of rubber and fiber electrical tape and put it back together.
I am pretty sure this is where the problem is. It smells pretty funky and the wires were not even together by the time I pulled away the melted plastic and tape. It was only 4" of wire so it could have been reconnected like new back to the wiring plate with new push-on clips. Maybe he just did not have any clips and went for the Neanderthal quick fix.
I am trying to attach a picture. I am wondering if since I have it out, would it be worth taking it somewhere to check out the motor before I put it all back together.
I am pretty sure this is where the problem is. It smells pretty funky and the wires were not even together by the time I pulled away the melted plastic and tape. It was only 4" of wire so it could have been reconnected like new back to the wiring plate with new push-on clips. Maybe he just did not have any clips and went for the Neanderthal quick fix.
I am trying to attach a picture. I am wondering if since I have it out, would it be worth taking it somewhere to check out the motor before I put it all back together.
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JPG
- Platinum Member
- Posts: 35600
- Joined: Wed Dec 10, 2008 7:42 pm
- Location: Lexington, Ky (TAMECAT territory)
drdale wrote:I just took the headstock apart. Just inside where the wire goes through the housing a previous owner had cut the wire for some reason and just hand twisted the wires back together and wrapped it all up in a ball of rubber and fiber electrical tape and put it back together.
I am pretty sure this is where the problem is. It smells pretty funky and the wires were not even together by the time I pulled away the melted plastic and tape. It was only 4" of wire so it could have been reconnected like new back to the wiring plate with new push-on clips. Maybe he just did not have any clips and went for the Neanderthal quick fix.
I am trying to attach a picture. I am wondering if since I have it out, would it be worth taking it somewhere to check out the motor before I put it all back together.
Pix posted here may provide us clues to help you.
Do you have a vom or something to measure resistance?
Smoking is not a good sign.
Did you find saw dust buildup inside?
Last, does the motor have a start relay or a simple start switch?
Folks here have first hand experience/knowledge with that somewhat unique motor/power switch/start circuit etc. 'Somewhere' most likely has not.
Which wire was neanderthaled(color)?
Also which brand motor?(GE/A.O.Smith)
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╟JPG ╢
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Goldie(Bought New SN 377425)/4" jointer/6" beltsander/12" planer/stripsander/bandsaw/powerstation /Scroll saw/Jig saw /Craftsman 10" ras/Craftsman 6" thicknessplaner/ Dayton10"tablesaw(restoredfromneighborstrashpile)/ Mark VII restoration in 'progress'/ 10E[/size](SN E3779) restoration in progress, a 510 on the back burner and a growing pile of items to be eventually returned to useful life. - aka Red Grange
╟JPG ╢
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Goldie(Bought New SN 377425)/4" jointer/6" beltsander/12" planer/stripsander/bandsaw/powerstation /Scroll saw/Jig saw /Craftsman 10" ras/Craftsman 6" thicknessplaner/ Dayton10"tablesaw(restoredfromneighborstrashpile)/ Mark VII restoration in 'progress'/ 10E[/size](SN E3779) restoration in progress, a 510 on the back burner and a growing pile of items to be eventually returned to useful life. - aka Red Grange
If the PO had to replace the wires going to the inside of the motor I think that it may be a GE. GE motors had a problem with the pigtails from the power switch to the motor. I have had to replace more than one set because because of this. I have not seen a GE motor that had a terminal plate in the motor. The GE motors that I have seen have flying leads that come out of the motors and go directly to the power switch
[ATTACH]21594[/ATTACH]
However these wires should be properly soldered to the motor windings when making this type of repair.
Bill V
[ATTACH]21594[/ATTACH]
However these wires should be properly soldered to the motor windings when making this type of repair.
Bill V
- Attachments
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- old wiring.jpg (80.35 KiB) Viewed 2128 times
Chapter 3
Now getting curiouser.
Obviously this is a Mark VII machine and is labelled as that, but when I was pulling out the bottom cowling holding the motor I saw that it is labelled as a Mark 7. Maybe the motor and bottom assembly was replaced at some point. The motor is an AO Smith Corp motor, C48L2A10.
I have a VO meter. What and how to test?
There was some fine dust inside the cowling but not that much.
It has a Dry Electrolytic Motor Starting Capacitor.
In the taped-up mess it looks like the black wire shorted out to the white wire.
The wires and clips on the board were in good shape.
THE OTHER MYSTERY
I did not remove the motor from the cowling. When I turned the cowling on its side a stainless part called the Plate Selector fell out. No idea where it came from in there, and the old parts diagram does not make it clear where it goes. Not sure what to do about that one.
Cannot seem to attach the picture. Keeps telling the the file is too big even though I manually reduced the file.
Obviously this is a Mark VII machine and is labelled as that, but when I was pulling out the bottom cowling holding the motor I saw that it is labelled as a Mark 7. Maybe the motor and bottom assembly was replaced at some point. The motor is an AO Smith Corp motor, C48L2A10.
I have a VO meter. What and how to test?
There was some fine dust inside the cowling but not that much.
It has a Dry Electrolytic Motor Starting Capacitor.
In the taped-up mess it looks like the black wire shorted out to the white wire.
The wires and clips on the board were in good shape.
THE OTHER MYSTERY
I did not remove the motor from the cowling. When I turned the cowling on its side a stainless part called the Plate Selector fell out. No idea where it came from in there, and the old parts diagram does not make it clear where it goes. Not sure what to do about that one.
Cannot seem to attach the picture. Keeps telling the the file is too big even though I manually reduced the file.
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JPG
- Platinum Member
- Posts: 35600
- Joined: Wed Dec 10, 2008 7:42 pm
- Location: Lexington, Ky (TAMECAT territory)
drdale wrote:Now getting curiouser.
Obviously this is a Mark VII machine and is labelled as that, but when I was pulling out the bottom cowling holding the motor I saw that it is labelled as a Mark 7. Maybe the motor and bottom assembly was replaced at some point. The motor is an AO Smith Corp motor, C48L2A10.
I have a VO meter. What and how to test?
There was some fine dust inside the cowling but not that much.
It has a Dry Electrolytic Motor Starting Capacitor.
In the taped-up mess it looks like the black wire shorted out to the white wire.
The wires and clips on the board were in good shape.
THE OTHER MYSTERY
I did not remove the motor from the cowling. When I turned the cowling on its side a stainless part called the Plate Selector fell out. No idea where it came from in there, and the old parts diagram does not make it clear where it goes. Not sure what to do about that one.
Cannot seem to attach the picture. Keeps telling the the file is too big even though I manually reduced the file.
When reducing pix sizes, the width cannot be greater than 800 AND the height must not be greater than 600. Either one will cause it to 'be denied upload'.
Do you have the original power switch? Illuminated three button labeled rev stop and fwd? Do you also have the key operated interlock?
The black and white wires from an A.O.Smith Mark VII motor are the run winding leads and as such are connected ACROSS input source. Any 'leakage' aka partial short between those two wires would indeed be a likely source of 'smoke'.
Before suggesting 'action', I would like to see pix of your funky wires and power switch. Oh and that stainless steel thingy also.
How do you know to call it a 'Plate Selector'? Stainless steel parts are usually not found in a SS. Could it be the light shield from over the switch?
All the Mark VII were labeled Mark 7 on that cover. Interesting quirk, but that is the way they were.
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╟JPG ╢
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Goldie(Bought New SN 377425)/4" jointer/6" beltsander/12" planer/stripsander/bandsaw/powerstation /Scroll saw/Jig saw /Craftsman 10" ras/Craftsman 6" thicknessplaner/ Dayton10"tablesaw(restoredfromneighborstrashpile)/ Mark VII restoration in 'progress'/ 10E[/size](SN E3779) restoration in progress, a 510 on the back burner and a growing pile of items to be eventually returned to useful life. - aka Red Grange
╟JPG ╢
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Goldie(Bought New SN 377425)/4" jointer/6" beltsander/12" planer/stripsander/bandsaw/powerstation /Scroll saw/Jig saw /Craftsman 10" ras/Craftsman 6" thicknessplaner/ Dayton10"tablesaw(restoredfromneighborstrashpile)/ Mark VII restoration in 'progress'/ 10E[/size](SN E3779) restoration in progress, a 510 on the back burner and a growing pile of items to be eventually returned to useful life. - aka Red Grange
stil not working
I cut out the bad section of wire and attached new clips.
Blew out dust from everywhere.
Put all back together again.
Turned it on and ran fine for a few minutes.
Kicked the breaker again.
It was not under any load, just running at high rpm with moulder attachment in place.
Motor was not very hot.
The plate selector was identified from the parts diagram. I think it is associated with the lock mechanism which has been removed from this machine it seems.
Blew out dust from everywhere.
Put all back together again.
Turned it on and ran fine for a few minutes.
Kicked the breaker again.
It was not under any load, just running at high rpm with moulder attachment in place.
Motor was not very hot.
The plate selector was identified from the parts diagram. I think it is associated with the lock mechanism which has been removed from this machine it seems.
This will be my last comment on this subject as I will defer to JPG as he is more of a motor guru than me. He also knows more about the switching of the Mk VII than I do.
I am confused by your wiring pic. Where was the green wire connected?
It is possible that the green (ground) wire was carrying some current and caused the breaker trip?
Is there any burned insulation further along the sheath of the power wire that you have not seen yet that is causing a short?
Is the breaker a GFCI or a standard breaker. A high resistance short from the hot lead or the neutral lead to the ground (green) wire will cause a GFCI to trip.
I would suggest that the AC line cord from the motor pan to the wall outlet and the wiring from the switch to the motor be replaced to eliminate any possibility of degraded power wiring. From the condition of the wiring in your pic I would consider all wiring to be suspect.
If you can, try to isolate the motor and run it by itself with a new power cord and bypass all of the switches to see if the motor keeps running. This will reveal if the motor is actually at fault.
I will read all of the future posts ,however.
Bill V
I am confused by your wiring pic. Where was the green wire connected?
It is possible that the green (ground) wire was carrying some current and caused the breaker trip?
Is there any burned insulation further along the sheath of the power wire that you have not seen yet that is causing a short?
Is the breaker a GFCI or a standard breaker. A high resistance short from the hot lead or the neutral lead to the ground (green) wire will cause a GFCI to trip.
I would suggest that the AC line cord from the motor pan to the wall outlet and the wiring from the switch to the motor be replaced to eliminate any possibility of degraded power wiring. From the condition of the wiring in your pic I would consider all wiring to be suspect.
If you can, try to isolate the motor and run it by itself with a new power cord and bypass all of the switches to see if the motor keeps running. This will reveal if the motor is actually at fault.
I will read all of the future posts ,however.
Bill V