The cpu of my Mackie D8b no longer recognizes the keyboard or mouse and won't boot up.This problem just started after many years of trouble free use.

There is a clock card inside you can not turn that unless you have an apogee clock card

This should be a fairly simple job, the only thing that may cause some people trouble would be if the switch has solder and not push on connections. This is an NO switch (normally open) Part # 00-087711-183-4 with two wires, one each to either connection.
1.Unplugged or turn the breaker off for the mixer, pull the cap off the start button.
2. Remove one of the lower screws from the electrical control panel plate and use it to get two screws 1 inch or longer that are the same size and thread.
2. Remove the other bottom screw from the control plate and screw the 2 longer screws into the bottom holes no more than one quarter of an inch. The screws will give you room to work and support the control panel plate while you are replacing the switch. Remove the 2 top screws that hold the electrical control plate to the machine.
2.Remove the 2 screws from the front of the control plate that secure the start button in place.
3. Install the new switch, make the electrical connections, replace the 4 screws in the control plate, and push the cap back on the start button, Plug in the machine or turn the breaker back on and you're done.
PS: you should avoid touching the other components on the electrical control panel.

I'm in the middle of a bake sale. Not a good time to send back. Also, I think you meant a free Upgrade at no additional cost...

http://www.mackie.com/ubbthreads/ubbthreads.php?ubb=showflat&Number=165618

Leave a comment if you need more help.
Thanks for using Fixya.

take it in to an appliance repair shop for a proper diagnosis and quote but it is probably not worth repairing ( armature and brushes )

You may have control circuit trouble, connection issues with the wiring, control board trouble, all rather rare; more common is side effect from attempt to keep a clean kitchen...
...Beneath large (plastic) screw heads each side of mixer are a spring, copper or brass cup, another longer spring and a carbon brush... which may NOT slide out freely- if not, thats doubtless the problem... the carbon has a corner ground off it to insure proper alignment and preserve the commutator (motor life) so it only fits in one way... wrong way it will jam up on the keying device inside the brass or copper brush holder into which it slides. (the key can be seen all the way inside the holder with aid of a flashlight)
IF THIS BRUSH HOLDER SLIDES OUT WITH THE CARBON YOU HAVE A MAJOR MAJOR JOB TO REINSTALL IT CORRECTLY!!! If the carbon becomes an issue you are best advised to use a factory recommended facility for the repair and avoid damage to the commutator or other issues. It may require total disassembly and removal of entire motor, which usually involves disassembly of the transmission in order to remove the armature. In other words, absolute TOTAL disassembly in the worst-case scenario.
Good luck- most frequently its a simple matter, but beware of the heads-up issue. Check the brushes first but put em back carefully.

Hi DAVEF159, Happy New Year! I’m sorry to hear about your new mixer. To answer your basic question, yes this is covered under warranty. By the description of your mixer’s symptoms it sounds as if your transmission has locked up or a gear has failed, which it shouldn’t do. This would cause the planetary/agitator shaft to stop rotating.
Since it is under warranty, contact them immediately and tell them about your problem with the stir speed not working. The KA website is at: http://www.kitchenaid.com/flash.cmd?/#/page/home.
Click on Customer Care>Contact Us> and you will find the toll free phone number listed to speak with someone. You can also look under the Warranty & Service Plans to see what KA will do for you. I've extracted parts of it here:
Hassle-Free Replacement Warranty
We’re so confident the quality of our products meets the exacting standards of KitchenAid that, if your mixer should fail within the first year of ownership, KitchenAid will arrange to deliver an identical or comparable replacement to your door free of charge and arrange to have your “failed” mixer returned to us.
Your replacement unit will also be covered by our one year full warranty. Please follow these instructions to receive this quality service.
If you reside in the United States and your KitchenAid® mixer should fail within the first year of ownership, simply call our toll-free Customer Satisfaction Center at 1-800-541-6390, 8 a.m. to 8 p.m.,
Monday through Friday, 10 a.m. to 5 p.m., Saturday, Eastern Time. Give the consultant your complete shipping address. (No P.O. Box Numbers, please.)
When you receive your replacement mixer, use the carton and packing materials to pack-up your “failed” mixer. In the carton, include your name and address on a sheet of paper along with a copy of the proof of purchase (register receipt, credit card charge slip, etc.).

I hope this helps. Good Luck with KA! - Howard, Burke, VA
If this solution has been helpful, please rate it, thanks! - hslincoln

you could have a bad swith for the cage, or the bowl height swith might be the problem also

I take out the led