Microwave turntable motor failed.

[Andrew]

Its a 17-yo Sharp microwave combi-oven which does a good job as a mini-oven because it has an upper and a lower grill element, so heats up quickly.

A few days ago there was a lot of graunching noises and the turntable no longer turns.

I have removed the synchronous motor and the gears are all fine. Turning the spigot with pliers rotates the motor itself, I can hear it.

It's marked AC220-240V 2.5.3 RPM 3/2.5Watts.

My multimeter says the contacts are 14.77 Kohms and if I connect direct to the mains it is dead, not even a buzzing.

This place sells them :-

But I'm not paying £102, when they should be obtainable for about

10 to £15.

Part is marked CHINA GPS Corp ST-16 synchronous motor

MN73SSAQ RMOTDA227WREO

There is a 2nd hand one on ebay for £10, but that might be dead too. An Amazon site has them for about £45. Still too much.

Any ideas who else might sell them ?.

Andrew

[Adrian Caspersz]

Do a google image or ebay search on Panasonic synchronous microwave motor

For about 5mins work with a hacksaw, should come in under a fiver for something that looks about the same. Can't be that critical...

[alan_m]

I doubt if there is much difference in the motors between manufactures. A general search on Ebay shows motors at under £10 and they all appear to be of the same two physical construction irrespective of the microwave models they are claimed to fit.

[Andy Burns]

Maybe the gearing changes, mine was 5/5 rpm (which I think means 5rpm on

50Hz and 6Hz on 60Hz)

the o/p seems to want 2.5/3 rpm

so maybe

if the D-shaft and pins are right?

[alan_m]

But does it really matter if a turntable revolves (slowly) at twice the rate?

[Brian Gaff (Sofa]

So its a small motor, like the ones in old electric clocks with a gear train? Are you absolutely sure the gears are ok? I'm assuming they are plastic, as otherwise they would get cooked. Brian

[Brian Gaff (Sofa]

It might load the motor more if its going faster. Brian

[Andrew]

It's rated at mains voltage and the connection lugs are important too.

[Andrew]

Yup, I bent back the four crimps holding the base on and the plastic gears are fine, plenty of grease still in there. Definately the motor at fault.

Andrew

[Andrew]

But that one looks quite promising. Worth a try.

[Andy Burns]

you say lugs, I say pins

some motors start in a random direction each time, others start in a defined direction, I don't know if any turntables care?

[Andrew]

Interestingly, I had always noticed that if I stopped microwaving porridge after 1 min, to give it a stir, then pressing start again the turntable would rotate in the opposite direction, after another minute the same stop/start would send it back in the original direction.

The motor only has two ?lugs for the electrical connection, so how would a synchronous motor do this ?. Hopefully the failed motor hasn't taken out a solid state component somewhere.

This microwave has three convection heaters, two quartz ones in the top and a conventional 'dark' element under the turntable. It gets up to temperature in a few minutes. No other combi/micro seems to have the lower grilling element and there are plenty of comments from people who say their Panny/Samsung/? take 30 mins or more to get up to 200C, or even never gets there.

My sharp oven can go up 240C (not that I have tried it), in fact until about 5 years ago I had never used the convection setting.

[Max Demian]

My Daewoo does that, though I think the direction is random. (The instructions warn you about this.) Synchronous clocks tended to restart backwards after a power cut unless there's a mechanism to prevent it, and a brush motor with a two pole armature would start either way; presumably that's why they always have an odd number of poles.

[tabbypurr]

Microwave oven motors are pretty much universal. Rotation speed varies a bit but doesn't matter at all.

NT

[Graham.]

+1