56 replies to this topic

[MrDave]

Greetings all and Happy New Year!

 

We have a Panasonic 1250 watt 2.2 cu ft microwave, model # NN-S954WF. The problem is when the door is opened, the turntable starts turning. Nothing else is running. Now when the door is open, if I push and release the big button that opens the door, the turntable reverses direction. The turntable does not rotate with the door closed and the oven off. Other than that, the microwave functions normally. I think I have narrowed it down to a faulty door switch, but I am not a professional. I could not find the part let alone a source for it. If it really is a door switch, what is the difficulty replacing it if I had a new switch? The oven works great other than this but my wife says to trash it and get a new stainless steel microwave. But if I can fix this one it will be WAY cheaper, but I can't locate the part if it is the door switch. What do youse pros think?

Thanks for any help you can provide.

MrDave

[jumptrout]

It's so easy a caveman could do it.

http://www.repaircli.../AMI2033/940337

[kdog]

[Cactus Bob]

Does the oven light work when the oven is cooking ?

 

Does the oven light work when you open the door ?

[MrDave]

The oven light works when the door is open and also when the oven is running.

[Cactus Bob]

Great , while reading your post . i just had a flashback to a microwave 20 years or so ago that the bulb burned out and there was a  cooling fan running slowly all the time

 

replacing the bulb fixed the problem

 

not your problem

 

but

 

I can't help but wonder , how a micro switch can make the turntable turn on

most microwaves use a relay or a SCR on the main board to send power to the turntable motor

I do know most relays use a small cap (.01mfd) across the relay contacts , if this cap should become shorted or semi shorted........ , but all this is just a guess

 

microwaves can use both power and common switching to control loads

this wiring scheme has had me chasing my tail more than once 

Edited by Cactus Bob, 01 January 2013 - 02:35 AM.

[MrDave]

It's strange that with the door open and I push the big button that opens the door, the turntable reverses direction.

[RegUS_PatOff]

... the turntable reverses direction.

most all M/W Turntables reverse direction every time they start

Has this M/W worked OK for you up till now ?

Any repairs done to it lately ?

[MrDave]

quote:

most all M/W Turntables reverse direction every time they start

True, but I was referring to the turntable reversing direction when the oven is off with the door open then pushing in and releasing the big button that opens the door.

 

It has worked perfectly up till this problem. No repairs have been done. I have never even taken the cover off.

Other than this problem, when it's running to heat something up, it's working the same as when it was new.

So the problem is, oven off door closed, nothing running, normal.

Open door with oven off, turntable starts turning, light is on, fan is off, magnetron tube is off.

Close door, light goes off, turntable stops.

Methinks it doesn't like me anymore...

[Cactus Bob]

the turntable motor is non directional , when it is powered up it's the luck of the draw what way it turns , it might run one way on 5 starts and then run the other on the 6th, there is just no pattern on some of them 

 

if this problem always happens it should be easy to check the 3 micro switches with an ohm meter and know for sure what the problem is or is not

 

there are no shortcuts

[MrDave]

I actually don't care which way the turntable turns, I just wondering why the turntable starts turning when I open the door.

That appears to be my problem. could it possibly be the door switch?

[Cactus Bob]

Door switch ? , stranger things have happend  . but i just don't see it

 

i would guess there is a better chance there's some part on the motherboard that is bad and when the door is opened the power from the light is getting over to the turntable somehow

 

but that is just a guess

 

I hate guessing

 

a multi meter takes the "guess " out of guesswork and leaves " work " 

 

I like "work"

 

get a ohm meter and check your door switches and "be sure"

[RegUS_PatOff]

I'm with Cactus Bob, would seem to be more than just a Door Switch.

I don't have a wiring diagram for that model,

unless you have one you could scan & upload somewhere ..

[certified tech group 51]

 Checked my micro wave and the turn table turns one way and if you stop it and restart it, it will go in  the opposite direction..............The door switches are basically  safety devices.  ( 2 ) ....It tells the control board that the door is closed...The other switch is the monitor switch..( 1 ) .....It tells the control the door is open.....I do not work on microwave units, so what I just stated could be a bit out of touch with reality.......BUT,  If you look at the wire diagram, look for  your turn table motor and trace it back to the control board, is there any other items on the same circuit???   Different relay's  but common neutral.......................P.S.  Ditto with Mr. Cactus'  post............. 

[MrDave]

My wife wants to get rid of this microwave and buy a new one, but if it's just a simple fix, why spend the money? What do you all think? should I persue to try to fix this one or bite the bullet and my wallet and buy a new one? other than the turntable running when I open the door, it works perfectly.

[tpoindexter]

If you haven't actually tried anything that has been suggested, then, please go buy one.

If you have been trying each suggestion, then, I wouldn't give up till I knew which component was bad. Then you'll know which option is best.

[RegUS_PatOff]

I'm with Cactus Bob, would seem to be more than just a Door Switch.

I don't have a wiring diagram for that model,

unless you have one you could scan & upload somewhere ..

[MrDave]

I don't have a wiring diagram, and I would not know what to check or even what wires to check. Even if I did, I don't think I would know what to do with the results of testing the wires. I wish I knew more about repairing appliances as I find it sort of fascinating. I'm a machinist/CNC programmer by trade, now the head of the Mfg Eng dept where I work. I'm not mechanically challenged by any means, but I'm not an electrical whiz on appliance repair, so I turn to all of you professionals to offer your wisdom and helpful advice. You helped me before when my gas oven needed a new ignitor. I ordered one and installed it with all of your help and I am grateful for that. But this problem I have with my microwave has me baffled, almost to the point of being pizzed off at it or myself for not knowing how to fix it. (sigh) So, what would all of you suggest my next step be? I do understand it's almost impossible to diagnose something like this without the unit sitting in front of you, but I'm all ears. Also, be advised, I'm not the type of person to get upset or angry if I don't get a solution here. We're all human and we all try our best to help, myself included when I have something to offer. I'm just grateful that this website exists for us appliance repair challenged people.

 

MrDave

[tpoindexter]

I don't know how to tell you a safe way to figure out the problem. Obviously your getting power to the motor when you shouldn't be, so, where's it coming from? If you could trace the electricity from component to component the result would lead you to where it's coming from. That would require you using a meter and working with the unit live which I wouldn't suggest.

Do you have a meter and know how to use it?

[Budget Appliance Repair]

You say you don't have a wiring diagram, are you sure about that?

 

Most all microwaves have a wiring diagram tucked away somewhere inside and if not a loose tech sheet tucked into to rear of the control panel almost all the counter top microwaves have the wiring diagram glued to the inside of the case.

 

If you haven't pulled the outer case/wrap off, do at least that and take a picture of the wiring diagram if there is one.

 

That's about the only way anyone here is going to be able to help you figure this out without being there.

 

My bets still on a bad door switch, most likely the lower switch, (probably the secondary switch), the primary - usually upper switch and the center/monitor switch will blow the fuse if they are not working in the correct sequence but I believe on some units if the lower switch has failed/welded contacts together then it can feed back thru the circuit and monitor switch to cause things like the turntable to turn and sometimes the cooling fan to come on when the door is opened.