Dryer Motor Possibly Short Circuiting

[EasyGoing1]

I've been troubleshooting a Kenmore clothes dryer and discovered on the PCB one lead from the relay that supplies 120VAC to the motor that spins the tub had completely blown itself clean away from the PCB. It did it with so much energy that it left ocean wave shaped bends in what was left in the solder that connected it to the PCB.

I suspect that the motor was shorting out for some reason, but I don't know how to test my theory. I don't want to plug the motor directly into 120 obviously, so is there any other way I can test it to see if in fact it is shorting? I know that reading the resistance in the motor could possibly show me almost no resistance even if the motor is good so is there some other way to verify my theory?

[sam_sam_sam]

Re: Dryer Motor Possibly Short Circuiting

Please post a picture of the motor that you are taking about

One note

Check and make sure that your motor is NOT shorted to the case of the motor if it is then it is trashed

You could try put a incandescent light bulb ( at least a 100 watt lamp or higher ) in series with the motor and see if there is any rotation if NO rotation
( you can try to help it start its rotation )
and the lamp or lamps —> and if the lamp is very bright then your motor is trashed do not go any further

Or

If you do see any rotation then could try on line voltage but make sure that you have a inline fuse just in case something is wrong with this motor

The fuse should be at least rated for what the lock rotor amperage is stated on the motor data plate

If this is not stated on the plate or there is no data plate then do not use anything high than 10 amps I would probably start with a 5 amp one and see what happens

One note I know that these fuses are some what expensive but this what I use when I am troubleshooting motors and or servo drives power supply and you will not burn up things trying this motor out

It should be a fast acking fuse type
KTK-R5 this is a very fast acting fuse
KTK-5 this is just a fast acting fuse

They are basically the same cost for these fuse about $20.00
The fuse holder is also about $20.00

If this is to costly then you could use a circuit breaker type but start with 4 amp one not a 5 amp
You could use something like this but they are slower to ack to shorts if you go this route Please use caution
https://www.amazon.com/AMP-50VDC-250.../dp/B00OGL697M

Here is where you can get one
KTK-5
https://www.grainger.com/product/EAT...g-Midget-4XC40

KTK-R5

https://www.grainger.com/product/EAT...ine-Fuse-4XC24

Fuse holder

https://www.grainger.com/product/MER...ger-Safe-4ZCP6

Some of these motor have a low / high speed centrifugal switch that sometimes gets stuck in the high speed winding and if left that way and you keep trying it will short out the winding

I hope this will help you

[R_J]

Re: Dryer Motor Possibly Short Circuiting

It likely developed a poor connection, arced and the wire burnt off. Post a couple pictures

[stj]

Re: Dryer Motor Possibly Short Circuiting

it could be siezed.
but we need to see if it has brushes or just a static coil.

[EasyGoing1]

Re: Dryer Motor Possibly Short Circuiting

Please post a picture of the motor that you are taking about

One note

Check and make sure that your motor is NOT shorted to the case of the motor if it is then it is trashed

It's quite an open design ... not much of a chassis to short out to ... and I didnt see any immediately visible signs of electrical damage on the motor when I was spinning the shaft and examining it under a flashlight while its still installed in the dryer...

You could try put a incandescent light bulb ( at least a 100 watt lamp or higher ) in series with the motor and see if there is any rotation

This was the sentence that made me smile ... that is an absolutely brilliant idea and i feel stupid for not thinking of it ... but holy hell... it would totally work in helping me figure out if this motor works or not.

if NO rotation ( you can try to help it start its rotation ) and the lamp or lamps —> and if the lamp is very bright then your motor is trashed do not go any further

Or

If you do see any rotation then could try on line voltage but make sure that you have a inline fuse just in case something is wrong with this motor

The fuse should be at least rated for what the lock rotor amperage is stated on the motor data plate

If this is not stated on the plate or there is no data plate then do not use anything high than 10 amps I would probably start with a 5 amp one and see what happens

One note I know that these fuses are some what expensive but this what I use when I am troubleshooting motors and or servo drives power supply and you will not burn up things trying this motor out

It should be a fast acking fuse type
KTK-R5 this is a very fast acting fuse
KTK-5 this is just a fast acting fuse

They are basically the same cost for these fuse about $20.00
The fuse holder is also about $20.00

If this is to costly then you could use a circuit breaker type but start with 4 amp one not a 5 amp
You could use something like this but they are slower to ack to shorts if you go this route Please use caution
https://www.amazon.com/AMP-50VDC-250.../dp/B00OGL697M

Here is where you can get one
KTK-5
https://www.grainger.com/product/EAT...g-Midget-4XC40

KTK-R5

https://www.grainger.com/product/EAT...ine-Fuse-4XC24

Fuse holder

https://www.grainger.com/product/MER...ger-Safe-4ZCP6

Some of these motor have a low / high speed centrifugal switch that sometimes gets stuck in the high speed winding and if left that way and you keep trying it will short out the winding

I hope this will help you

THANK YOU SO MUCH ... so far you have been the only one who has actually given me something other than shrugged shoulders .... as I was reading what you were saying about the fast acting fuse ... a thought came to me ... what about taking a standard light dimmer and turning it to max resistance then putting it in series with the motor then plug 120 in and SLOWLY turn the dimmer (potentiometer) while watching current draw on a meter to see if the motor is drawing too much current and not moving etc. Would that work in determining if it's no good?

[EasyGoing1]

Re: Dryer Motor Possibly Short Circuiting

it could be siezed.
but we need to see if it has brushes or just a static coil.

The shaft spins freely ... like its floating on air actually ... it was surprisingly functional and still tight in the bearings ... no play in the shaft worth mentioning ... maybe ever so slight ... like the width of a hair or two... but when I spin the shaft and let it go it will keep spinning for a couple of seconds.

[EasyGoing1]

Re: Dryer Motor Possibly Short Circuiting

It likely developed a poor connection, arced and the wire burnt off. Post a couple pictures

I think this pic says it all ...

[stj]

Re: Dryer Motor Possibly Short Circuiting

remove the cover where the terminals are - there may be a bunch of surpression caps in there - it definatly looks like it's housing something.

[goontron]

Re: Dryer Motor Possibly Short Circuiting

I think this pic says it all ...

That looks like arcing damage to me. Personally i would stuff that motor across the mains without hesitation.

[R_J]

Re: Dryer Motor Possibly Short Circuiting

Clean and Resolder the the relay connection, reassemble and start drying clothes

[sam_sam_sam]

Re: Dryer Motor Possibly Short Circuiting

Some of these motor have a low / high speed centrifugal switch that sometimes gets stuck in the high speed winding and if left that way and you keep trying it will short out the winding

I hope this will help you

Yes this does have a low / high speed centrifugal switch you need to make sure that it is working correctly and that you are not stuck in the high speed ( or stuck in the low speed winding ) winding because you are suppose to start with the low speed winding first then when it speed up to a certain rpm then it switches to the high speed winding ( this happens all in a matter of second or less at full voltage )

The centrifugal switch arm is the device that has two springs next to where the terminal block is where you make the connections for powering the motor

PLEASE make sure that if you remove any of those terminals off that terminal block that you exactly where they came off from and they go back on in the same position other wise you can burn this motor up take pictures before you start

You can try the centrifugal switch by hand you should be able to move it fully open position
and should move freely with out getting stuck in any position

If it sticks you can clean it with brake clean and let completely dry before you apply power to the motor if you do not follow this the brake clean can catch fire this will not be a good thing trust me I have had it happen to me before

You can also check that the centrifugal switch opening and closing the circuit the switch terminals should be marked let you know what position they are in when in the normal position
( check all the terminals ) when you move the centrifugal switch arm

I would still try it with a incandescent light bulb in series with the motor and should start turning by it self you might have to use a 200 watt light bulb for this to work

If this motor works right it should start turning and speed up then when it gets to certain speed you should hear something like something being slinging out words and then speed up to full speed

[sam_sam_sam]

Re: Dryer Motor Possibly Short Circuiting

I was reading what you were saying about the fast acting fuse ... a thought came to me ... what about taking a standard light dimmer and turning it to max resistance then putting it in series with the motor then plug 120 in and SLOWLY turn the dimmer (potentiometer) while watching current draw on a meter to see if the motor is drawing too much current and not moving etc. Would that work in determining if it's no good?

This is NOT a good idea and here is why

There are motor controller that are made to do this but you can not buy them from Home Depot or Lowe’s I will give you a website where you can buy one if you want to go this route

But I am going to give you a word of CAUTION about doing this
If this motor has a kind of major problems you will fry the triac in the motor controller if you do not use a very fast acting fuse

If you going to do this use something like this

https://www.ebay.com/itm/10000-W-Hig...oAAOSwkhtcsESm

Put the fuse on the ( black wire ) to the input ( marked “ in “ on the wiring diagram on the motor controller ) of this type motor controller the ( black wire ) output terminal ( marked “ out “ on the motor controller wiring diagram of the motor controller goes to your motor the ( you might not have white wires they all maybe all black wires instead ) the other wires is your common wire from your motor an the motor controller

Also when you go to try this here is another word of CAUTION

When the motor starts to turn you need to turn the motor controller to fully ON or you can ruin the motor if you leave in low voltage / high current state for to long

In a former life I use to work on washer and dryers microwave and the like for a little while I had to run away from this type of work it does not pay very well

I hope this helps you

[ron350]

Re: Dryer Motor Possibly Short Circuiting

EasyGoing1 what is the dryer model #?

[redwire]

Re: Dryer Motor Possibly Short Circuiting

Just resolder all the high-current connections on the board.
Vibration is high on a clothes dryer and stresses connections.

The Kenmore/Maytag/Whirlpool dishwasher fires had the same problem - PCB fractured soldering joint at the power relay. It arcs, made heat and cooked the relay and board until your house burned down.

I wouldn't blame the motor. It is an inductive load and will trash any poor connection, and the windings would look burnt if it was shorting out.

[EasyGoing1]

Re: Dryer Motor Possibly Short Circuiting

EasyGoing1 what is the dryer model #?

It is a Kenmore gas dryer, model #: 110.94832201

[EasyGoing1]

Re: Dryer Motor Possibly Short Circuiting

Just resolder all the high-current connections on the board.
Vibration is high on a clothes dryer and stresses connections.

The Kenmore/Maytag/Whirlpool dishwasher fires had the same problem - PCB fractured soldering joint at the power relay. It arcs, made heat and cooked the relay and board until your house burned down.

I wouldn't blame the motor. It is an inductive load and will trash any poor connection, and the windings would look burnt if it was shorting out.

In this case, however, the relay still works fine. I took it out of the board and tested it. If there was any kind of arcing happening wouldn't I see damage on the board in two places?

[redwire]

Re: Dryer Motor Possibly Short Circuiting

Just to be clear, you have the same bad connection at a relay terminal on the PC board as the pics below? Bosch dishwasher that has bad connection just like your dryer pic.
It's a common problem in appliances. Vibration or poor soldering fractures the joint, it arcs (tiny, inside the hole) and spews out solder vapor and gets worse.
To fix it, if the relay is not damaged from the heating, just clean the joint and resolder it.

The Whirlpool, Kenmore, or Kitchenaid dishwasher class action suit, you get $100, or 30% buying a new one. It was the same bad connection arcing.

[EasyGoing1]

Re: Dryer Motor Possibly Short Circuiting

remove the cover where the terminals are - there may be a bunch of surpression caps in there - it definatly looks like it's housing something.

I took these just for you ... if you want closeups of any areas let me know.

They coat this board with some kind of lacquer and when I cleaned up all the lint material with rubbing alcohol it reacted a little with the coating causing somewhat of a mess but it looks better than it did with all the lint and dust on it.

[EasyGoing1]

Re: Dryer Motor Possibly Short Circuiting

Just to be clear, you have the same bad connection at a relay terminal on the PC board as the pics below? Bosch dishwasher that has bad connection just like your dryer pic.
It's a common problem in appliances. Vibration or poor soldering fractures the joint, it arcs (tiny, inside the hole) and spews out solder vapor and gets worse.
To fix it, if the relay is not damaged from the heating, just clean the joint and resolder it.

The Whirlpool, Kenmore, or Kitchenaid dishwasher class action suit, you get $100, or 30% buying a new one. It was the same bad connection arcing.

Wow, that looks EXACTLY like what happened here ... I suppose the worse that could happen is that I get it cleaned up and re-soldered and if the issue is with the motor then it will just do it again ... if not, then the problem is solved.

I will take the motor out and do a much closer visual inspection of it and all the windings that I can see just to make sure there is no obvious issues with it.

When I got sucked into this problem, I was at my friends house and she started to hang up her clothes to dry so i asked her if her dryer was broken and she said yes ... so I asked some questions then got sucked into it ... but its been a great learning experience since I've never taken apart a dryer before. I guess I was most surprised with how simple they really are conceptually ... I had never really thought about it before.

[EasyGoing1]

Re: Dryer Motor Possibly Short Circuiting

The Whirlpool, Kenmore, or Kitchenaid dishwasher class action suit, you get $100, or 30% buying a new one. It was the same bad connection arcing.

Do you think it would be a good idea to go over this board and re-enforce all solder joints that handle AC?