Question about KitchenAid KSM90 Ultra Power Series Stand Mixer

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Speed Control Unit test?

Does anyone know how to test the viability of the speed control unit? My mixer stopped turning on. The power cord appears to be fine (according to my voltmeter), and the motor/gears all appear to be in working order.

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  • 3 more comments 
  • pokenmeister Aug 19, 2008

    :) Allow me to mention that whatever the problem is, it's keeping the mixer from running.

  • pokenmeister Aug 21, 2008

    The switch is working properly.

  • pokenmeister Aug 21, 2008

    The switch is working properly.

  • pokenmeister Aug 21, 2008

    also working properly.

  • pokenmeister Aug 21, 2008

    Both spin properly. I think the problem is in the control board itself (one of the resistors burnt out, etc). When I posted earlier that the switch was working, I was referring to the switch that closes the circuit on the speed control plate, which does drop when the speed lever is moved to the 'on' position. I'm getting strange resistances, when I try and check them against the color code, but I'm not certain how they're wired (parallel vs. series), so I don't know what values I should expect.


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  • 45 Answers

Take off the back cover. there should be 2 screws on top of a piece of metal, 1 on bottom. Start on turn. it should go about 1x a second. Turn the top scrws. Then go to 6. it should be 3x a second. Use the bottom screw to adjust that. When turn and 6 are corrrect, all other sppeeds are right. There might be something else in between the back cover and the 3 screw panel.

Posted on Aug 19, 2008

  • 2 more comments 
  • ae_7fam Aug 21, 2008

    Is the switch (the speed control) working? Check that.

  • ae_7fam Aug 21, 2008

    How about the cables from the motor to the switch?

  • ae_7fam Aug 21, 2008

    So does the motor spin but not the planetary?

    That is the "spinning part"

  • ae_7fam Aug 28, 2008

    Ok. See what you can do.


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1 Answer

My mixer stopped working. Nothing happened, just went to use it one day and it wouldn't turn on. What could the problem be?

The problem could be anywhere and it should be checked through by a competent person using test equipment.

There is a slightly higher chance the power cord has an internal break but other common problems are with the internal safety device, the speed control, the switch or the motor brush gear.

Nov 21, 2016 | Food Mixers

1 Answer

The unit will not power on. There is no noise when the the speed selector is in the on position. The electric socket works, the beater can be turned by hand, but the unit won't power on

This model as configured for NZ will not start unless you move the speed control from the off position to any one of the speeds. In other words it will not start if you turn it on at the wall when the speed control lever is already in any on position. You must start from the off position first. I have also seen one fail to operate because the power wires from the speed control to the motor had come slightly unplugged inside the housings.

Apr 09, 2016 | KitchenAid Professional Heavy Duty Series...

1 Answer

My KitchenAid KSM90 will not turn on at all.

First make sure that the mixer is plugged into a working outlet. Were there any symptoms the last time you used your mixer? Check the cord on the mixer for damage. If the cord shows any wear replace it immediately.

At any point in time have you removed the brushes or adjust the speed control plate? After checking the cord, remove the brushes from the mixer, check to see if they are pitted, if they are replace the brushes. Please pay extra attention when putting the brushes back in the mixer, there is a dog-eared side of the brush, match this up to the brush holder to make sure the brush is inserted correctly.

If the brushes are not the problem check the speed control plate. If you remove the end cover from the mixer you can gain direct access to the speed control plate. There are 3 screws on this plate, the top two are used to adjust the speed of the mixer, the bottom one spaces the on/off switch contact. Try adjust the bottom screw to see if the mixer will turn on, it is possible the on/off switch was out of place.

Try these first, if none of this works let me know and we can continue trouble shooting.

Here is a link to the cord for your mixer:
Here is a link to the brushes:
Here is a link to the speed control plate:
And here is a link to the service manual for your mixer, it has more troubleshooting ideas on the last few pages:

Thank you,

Customer Service

Apr 13, 2013 | KitchenAid KSM90 Ultra Power Series Stand...

1 Answer

Mixer only runs at one speed

if it runs only at high speed it needs a new phase control board if the mixer is post 1978, if the mixer is pre 1978 then you will have to replace a capacitor on the end of the power cord inside the mixer. if the mixer only works on one speed that is not high speed then you need to adjust or replace the speed control plate on post 1978 mixers and the capacitor on pre 1978 machines. Hope that helps

Jan 30, 2013 | KitchenAid Food Mixers

1 Answer

Kitchenaid deluxe 5 edition stand mixer runs on speed 10 and after 30 sec stops I thought it was the speed control pannel then I order one online and change it but that work 2 times and i have the original...

In the Artisan mixers the problem can be caused by two different parts. First the speed control plate. When you remove the end cover from the mixer the first thing you see is the speed control plate. There are 3 screws on this, two at the top, one on the bottom. Try adjusting the top two screws, to adjust, turn in the control plate adjusting the screws an equal amount.
Also check to see if the control plate spring is unhooked. Remove end cover, and check control plate spring. If unhooked, attach to bottom of the control plate and squeeze the spring end.
It can also be caused by incorrect wiring, check the wiring, the last page of the service manual will be a wiring diagram for your mixer. Here is a link to the service manual.
Last, if the control plate is properly adjusted, the control plate spring is hooked correctly and the wiring is correct you will need to replace the speed control phase board. With the line cord disconnected, pull the t-bar contacts to open and insert a piece of paper between them so they cannot close. Reapply power-the mixer should just run or buzz trying to run. If it operates at full speed, the phase control is defective and needs to be replaced.
Thank you,
Customer Service

Jan 27, 2013 | KitchenAid KSM150PS Artisan Series Stand...

1 Answer

My kitchenaid mixer run on high at all times

If your mixer only runs on high speed there are 3 things that can cause that. The first thing to check will be the speed control plate, Remove the trim and end cover on the mixer, the first thing you should see is the speed control plate, this has 3 screws on it, try adjusting the top two screws 1/4 turn, this should slow the mixer down, do not over tighten. Also check to see if the control plate spring is unhooked. If the spring is unhooked, attach to bottom of the control plate, and squeeze the spring end.
If this does not fix your mixer, check the wiring of the mixer, you can locate a wiring diagram on the last page of the service manual.
If the speed control plate is adjusted correctly and all the wiring is correct it will be your speed control phase board. You can test the speed control phase board to see if it is shorted. With the line cord disconnected, pull the t-b ar contacts to open, and insert a piece of paper between them so they cannot close. Reapply power-the mixer should just run or buzz trying to run. If it operates at full speed, teh phase control board is defective and needs to be replaced.
Here is a link to the service manual:
This will aid you in taking the mixer apart, troubleshooting and putting it back together, remember the wiring diagram is the very last page.
Thank you,
Customer Service

Jan 07, 2013 | KitchenAid K5SS Mixer Speed Control Plate...

1 Answer

Kitchenaid stand mixer motor is dead and mixer won't turn on

There are a few reasons this might happen from ugly to easy lets start with easy and work to ugly.
1. check the outlet you are plugging the mixer into...I know I know but it does happen
2. The cord on the mixer might have a bad connection or one of the flag terminals may have come loose or broke, remember all metal fatigues. If you know how to uses a multi meter an easy check by removing the rear cover and check the power on the contacts from the end of cord that plugs into the wall and then goes into the mixer, you can check by Ohms testing (safer) or by live connection to the outlet in the wall.
3. The brushes on the mixer, one or both may have reached end of life, easy and inexpensive fix. They are under the big plastic screw covers that you see on the side of your mixer. BTW they can only go in one way and if not replaced correctly the mixer will not work even if you have a brand new mixer.
4 The mixer may need a new speed control plate rather more involved because you have to speed tune the mixer after it is replaced but inexpensive and can be performed by anyone from the rear of mixer. BUT!!!! The speed control board may not be bad but only that the mixer needs to be speed tuned.
5. It may be a phase control board gone bad, it is behind the speed control plate, again it can be replaced relatively easily but you also will have to speed tune the mixer and it will be a double digit cost on the part ($25.00-$30.00 unless you go to the internet and search sites, you may find on eBay for 12-15 dollars plus shipping.
6. We are now entering the ugly phase. the items above are all the electric problems that you can fix easily and inexpensively. The next requires a complete tear down of the mixer to replace the Stator and or Armature (the motor). You can do it but it will cost around $60-$70.00 dollars for the motor and then $6.00 for a new gasket which you will need as soon as you open the motor head. Some peeps just re-use the old I would not.BUT!!!!
7. The gears may have stripped while you were using the machine on high and has frozen up so that when you turn it on it won't work. If that is the case then the mixer will have to have the gears and grease and gasket repaired. Gasket=$7.00, Grease=$17-$24.00, it only comes in quarts and you get 30 ounces but only need 6 for a re-grease, Gears, there are 3 and they run between $10.00 for one and up to $30.00 for the pinion tower. No way to tell from the info you sent.
I have been fixing kitchenaid mixers for a while and I am only now replacing my first motor. So I think it is an easy to intermediate fix, DIY could spend 3 hours doing and spend $30.00 bucks on parts. The ugly $150.00 to $175.00 and I would recommend a service center do the motor because they will check all gears repack grease install new gasket and do a speed tune when they fix it.

Kitchen aid mixers are great and sometimes need a little TLC and they will last for years and years. If you could explain further exactly what happened during the speed run up and what you were mixing and what model and serial number (can be found on white sticker under base of mixer in the base cavity). then I may be able to narrow down the repair / fix path. If this helps at all please let us know we like to hear if we are able to help.

Sep 18, 2012 | KitchenAid KP2671 Professional 6 Series...

1 Answer

Mixer will not come on. is there a reset buton?

Most of the sets come with a reset trip /load trip which can be seen on the side or underside of the unit.
so please check your power cord to leadd to the unit .If there is none it wil go to the power switch or the speed control unit.
Check the switch trace power to the motor, if power comes in , the motor must be checked.

Sep 29, 2010 | KitchenAid K5SS Heavy Duty Commercial...

1 Answer

Mixer only operates at high speed regardless of the speed setting

the triac solid-state component on the board for the motor speed control is shorted and you need a new control board, unless you can find an outsource replacement triac,most companies won't sell you parts because of liability issues on internal parts of the unit

Apr 02, 2010 | KitchenAid K45SS Classic Stand Mixer

2 Answers

The speed control doesn't work well

This problem could be due to a worn or broken speed governor. this part is located on the motor shaft of the unit and works by way of centrifugal force. This however when gone will usually make the mixers speed go up and down, not just one speed. The most likely cause of this problem is the main control board. if this has become faulty, it can make the mixer stop completely or in your case, run full speed when turn on. part number for the board is W10119326. this part can easily be changed by disconnecting all power and removing the back end cover. Once removed make note of the adjustment screws at the bottom of the board. As these are your motor speed adjustment screws, and can be very finely tuned. Once these and the spring has been removed. you can now replace the board. Hope this helps


Nov 01, 2009 | KitchenAid K45SS Classic Stand Mixer

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