Emerson Model MW8625W Microwave Oven Timer Motor Repair

May 2012, Last Updated January 2014

May 2012-This oven uses an electro-mechanical design for timer

and power control. The timeswitch unit quit timing a couple of

years ago. I fixed it this past week. The motor armature was

separated into three parts, due to failure of the adhesive that

held the parts together. I re-cemented the parts together using

“Radio-TV Service Cement” which is a liquid toluene based cement.

I do not know how long this repair will last.

Updated July 2013- The service cement repair failed after a few

weeks. I re-did the repair using 2-hour Epoxy, and the timer has

been working fine ever since (over a year, as of July 2013, of

almost daily use).

To remove the control panel, do this;

(Goes without saying) Unplug the oven before working on it.

Remove the three ‘Torx” fasteners that hold the steel cover

and lift it off of the oven.

Unplug the two connectors attached to the Timer unit.

Open the oven door. This is important for easy removal of

the control unit.

Remove the one Phillips head fastener that attaches the

Timer unit to oven cabinet.

There is a plastic lever that sticks out of the control

unit to engage the door latch mechanism. Carefully rotate

control unit to clear door latch mechanism and then lift

the control unit out of cabinet.

Schematic for Emerson MW8625W Microwave Oven

Unsolder the two wires, hold the control unit motor-side

down, and carefully lower the motor (Labeled “Timeswitch

Unit”) vertically from the control unit. The output shaft

should come right out with the motor. You should not need

to take apart the white plastic gear-box unless the drive

shaft falls inside it during disassembly or reassembly.

Set the motor flat on its back on a tabletop, so that you

can carefully bend back the four holding tabs and lift the

cover plate. The cover plate is no longer fastened to the

case, like it was before I worked on it. See photo below.

FUSE, 15A

(12A OK)

DOOR

INTERLOCK

1

RED RED WHITE

GREY

GREY

TIMER

MOTOR

MAGNETRON

TRANSFORMER

BLUERED

LAMPTURNTABLE

MOTORFAN

WHITE

GREY

DOOR

INTERLOCK 2

DOOR

INTERLOCK

3

120VAC

INPUT “TIMESWITCH”

UNIT

0.7uF

2100VAC

TIME

POWERCONTROL

KNOBS

MAGNETRON

HV

DIODE

Disassembled Timeswitch Motor, “Open Clamshell” View

Gear #2 consists of two separate parts, a gear and a cam.

Reassemble the motor in gear number order shown above. The

armature consists of a toroidal magnet, a nylon back bushing,

and a nylon gear with two cam stops. The armature can start up

in either direction. The purpose of the armature cam stops and

the gear cam (part of gear #2) is to force the armature to turn

in the correct direction if it should happen to start in the

wrong direction. The years of repeated torque impulses of these

armature start-up events probably caused the adhesive failure.

January 6, 2014- A couple of weeks ago the timer started making

noise and quit timing again. I thought the motor armature broke

again, but today I disassembled the motor and the armature was

fine. I reassembled the motor and it worked fine. I don’t know

what went wrong.

When I reinstalled the motor to the timeswitch unit it all

worked fine. Then, as a precaution, I installed a cardboard shim

underneath the motor to press its cover plate on more firmly

when the motor is fastened to the gearbox. I reassembled and

retested the unit yet again, and it is all still working fine.

The complete microwave oven is working fine now.

ARMATURE

OUTPUT

SHAFT GEAR 6

6

5

4

3

21

12

3

4

5

PLACE TAB ON THIS CAM

INTO THIS SLOT

You can test the timeswitch/gearbox unit by itself. Use the

photo below as a guide.

AC Line Connection to Timeswitch unit for Functional Test*

*I took this photo while one motor wire was disconnected, but it

must be re-soldered to the terminal indicated by the red arrow

to test the assembled unit. When the timeswitch unit is

installed in the oven, the unconnected terminal at bottom left

goes via a red wire to the primary of the magnetron’s power

transformer. See also the schematic on a previous page.

While it was off of the gearbox I measured the motor’s output

hub speed as exactly 3 rpm. The motor looks exactly like the

#15QBP4184 turntable motor used on many Sharp brand microwave

ovens, but it has a design feature that forces the output shaft

to always rotate counterclockwise, as viewed from the cover

plate side of the motor. I don’t know if the Sharp turntable

motors do that.

THE END

120VAC

MAKE SURETHIS WIRE IS CONNECTED!

The Emerson motor’s label and part number, KX63501D, are for the

entire motor plus gearbox assembly, as evidenced by the

inclusion on the label of the ratings for the two SPST switches

inside the gearbox. In ERParts.com catalog I found a turntable

motor that is rated as 3 rpm, has same five- spindle pattern on

cover plate, and appears to have same output shaft hub pattern

as the Emerson motor, so it might work as a replacement

(provided that it always rotates counterclockwise).

Potential Substitute Motor from ERParts.com catalog

It is available for $16.24 from http://www.patriot-

supply.com/products/showitem.cfm/ERP_15QBP4184, or more from other

sites.

15QBP4184 Photos from RepairClinic.com, but they say “Not Available”