Maytag Dryer MDE7400AYW

[jambatt]

Need wiring diagram.

[Samurai Appliance Repair Man]

PMed you the service manual, which has a wiring diagram in it but the one on the tech sheet is preferred. Can't find the tech sheet right now, maybe Reg can sniff it out.

[RegUS_PatOff]

seems no separate wiring diagram ..

too many combinations of Dryness / Chime Boards ..

service bulletins

TDL-0057-B.pdf

TDL-0040-B.pdf

links PM'd

[jambatt]

Thanks for the info. Really need help on this one. Wiring diagram on page 10-19 of service manual. Installed new timer, thermal fuses OK, door switch checks out OK and Motor runs when jumped pins four and five. Still will not start when timer switch is pulled out.(Not a push to start switch) Can't figure out why power is not getting to motor. HELP!

[RegUS_PatOff]

.. Motor runs when jumped pins four and five.

which Motor pin numbers ?

(or wire colors) ?

10-19 has a push to start switch

6 pin Dryness Control Board and separate Chime ?

5 pin Dryness Control Board and separate Chime ?

OR 14 pin Dryness / Chime Board ?

[jambatt]

Page 2-5 Motor Cord Test terminals 4 and 5 (See Figure 2-4). Motor runs when connector is unplugged and test cord is connected to terminals 4 and 5 on the motor. Wiring diagram shows it as a push to start switch but this one works more like a washing machine timer where you turn to the setting and then pull out on the knob to start dryer. Like a push to start in reverse. Light on electronic dryer control lights when knob is pulled all the way out but goes out when you release knob. Irene has already kicked my butt and this dryer is adding insult to injury.

[RegUS_PatOff]

6 pin Dryness Control Board ?

When it should be running, is there 120v at the Motor pin 4 (Gray wire) to chassis (ground) ?

[jambatt]

Can't remember if 120v at terminal 4 to ground when pull to start switch is engaged. Will check tomorrow to be certain. Centrifugal switch checks out for continuity when manualy engaged. With power on and centrifugal switch manually engaged, the heater coil came on so that circuit appears to work correctly. Motor ran when power applied by jumper cord to terminals 4 and 5 so overload protector and motor appear to be OK. All roads seem to be leading to the electronic dry control. It appears that terminal 5 on the motor traces back through the timer to pin 4 on the EDC. I'm not as good as I need to be in determining the current flow in these diagrams. Have a hard time relating the actual mechanical parts to the drawing symbols. The timer dial indicates three cycles. Two intellidry cycles and an air fluff cycle. It appears from the diagram that when the pull to start switch is engaged, power flows through the timer motor to the EDC on pin 5. Pin 4 on the EDC then traces back to terminal 5 on the motor and then back to neutral through the door switch when the centrifugal switch is engaged. Since there is no diagram for the EDC, I'm not sure how it affects the start circuit but all the other components appear to check out OK, so I assume the EDC is the problem. Is this a valid assumption. Would like to be certain and not play parts monkey.

[RegUS_PatOff]

I think the EDC only controls the Timer Motor.

The Timer (section 4) should send L1 through the (2) Thermal Fuses,

then onto the Motor pin 4 Grey

Neutral goes through the Door Switch to Timer (section 3)

and onto the Motor pin 5 Red

once the Motor is running, Neutral goes through the Door Switch and to Motor pin 6 (?) White

[Budget Appliance Repair]

I think you have a timer problem. The wiring diagram is a little lacking without the timer chart to go with it to tell what contacts should be open/closed in what cycle position and more importantly which of the contacts are the pull to start.

I'm pretty sure contact #3 is the pull to start switch, (YL#34 to RD#31)

These new plastic timers are pretty cheesy, the point contacts start to get arched and create heat which melts the plastic cam follower tips off the contact arms.

Not to long ago I had a very similar Maytag dryer and it would start but you would have to pull and hold the knob just right to get it started. Replaced the timer and all was OK.

Should be able to put in air fluff cycle and even if dryness board were bad I believe it wouldn't even be in the circuit for air fluff so if the dryness board were the problem it should run OK in air fluff?

[RegUS_PatOff]

.... Installed new timer ...

[jambatt]

Thanks Willie. The timer was replaced initially because the shaft for the knob was broken, so we're dealing with a new timer. Finally figured out section 3 represented the pull to start switch as you state. And Reg, I finally came to the same conclusion that you state after a lot more work with VOM. That being said, see if this makes any sense. When the timer knob is pulled out initially, contacts are closed in sections 1,2 4, and 5. Power leaves the contact in section 4 on the Purple wire and passes through the thermal fuses and on to terminal 4 on the motor via the Gray wire. It then travels through the start coil and through the centrifugal switch back to the pull to start contact in section 3. When the pull to start switch is engaged, the section 3 contacts are closed completing the circuit to neutral through the door switch via the Yellow 34 wire. When motor starts, the centrifugal switch contacts close and power now travels through the run coil as neutral is now shifted to the white 34 wire and back through the door switch and power no longer travels through the start coil. So if the contacts in section 3 are closed to complete the neutral and the motor doesn't start, the start coil must be open.

[RegUS_PatOff]

I agree, up to the Start Coil ...

Does the Motor "hum" when the Start Switch is pulled out ?

If yes, then the Motor may be bad...

If no, is there 120v AC (to chassis, ground) at Motor pin 4 Gray wire ?

How's the Door Switch ?

[jambatt]

Door switch working properly. Motor does not hum when switch pulled out. 120v at terminal 4 on motor to chassis ground.

[RegUS_PatOff]

... 120v at terminal 4 on motor to chassis ground.

OK

then should be 0v at Motor pin 5 Red when Switch pulled out.

If not, check for 0v at Motor pin 6 White

[Budget Appliance Repair]

Have you checked the power cord terminal block for loose wires? Maybe a loose neutral failing to carry the load?

[Samurai Appliance Repair Man]

Good thought, Willie. Jambat, also check for a bad neutral connection in the circuit breaker box-- been burned by that one myself ==> http://fixitnow.com/wp/2004/08/01/war-story-kitchenaid-dishwasher-kudc25chwh1-dead/

[Budget Appliance Repair]

Good thought, Willie. Jambat, also check for a bad neutral connection in the circuit breaker box-- been burned by that one myself ==> http://fixitnow.com/...dc25chwh1-dead/

I should have thought to mention that also, as I just a had one of the good old Hobart style Kitchen-Aid dishwashers that I had that exact problem with. Got a reading of only 102 volts at line to neutral and nothing, not even any lights would come on. Had a good 120 volt reading from hot to the body of the dishwasher.

Neutral line to dishwasher in circuit break panel box had a loose neutral bus connection.

[jambatt]

Bingo......Loose neutral in breaker panel. Thanks to everyone for all the help.

[Samurai Appliance Repair Man]

Domo for letting us know. Glad you nailed it!