Question about microwave ovens

[jeffg]

Last night our Panasonic microwave oven (model# NN-6469) wouldn't turn on. It's the first trouble we've ever had with it (the manufacture date is Dec. 1989). The timer still counted down as if the oven was running, and the interior light still worked as it should, but the magnetron didn't start and the turntable didn't rotate.

I opened it up and one wire socket was a bit loose, I plugged it back in all the way and now it's working again.

My partner is nervous because of the unit's age, and he still wants to replace it even though it seems extremely well built. My question is, do these ovens have an upward limit with regard to how long they should be allowed to run? Aside from a very small amount of dust in the fan (which I blew out), I saw absolutely no signs of wear inside.

Thanks for any info!

 

[tolivac]

The magnetron tube in older ovens can age-it makes the oven take longer to cook becuase the microwave output of the tube is lower.
Check the door seals are they dirty or worn?dirty or worn door seals can cause microwave leakage-its very rare-but could happen.Fortunately with dirty seals you can clean them.Also microwave oven doors have what is called the quarter wave seal-backup to the door seal.The quarter wavelength seal acts like a quarter wave line filter to absorb stray radiation.-shunts it to ground.This should still work even if the cooker is old.For the most part magnetron tubes in microwave ovens can last for many years.You can test it-see how long it takes for the oven to boil a cup measure of water.In the owners manual it should tell you how long it takes for the oven to boil it.Try it with your machine and see if its the same or takes longer.That will tell you if the tube is aged.Testing door seals is another matter-a microwave oven technician has seal leakage testers.

 

[petek]

I don't see why other than leaking it should be fine. I have a meter I got at Radio Shack years ago back in the 80's to check for leaks around the door. Our MW is even older and it runs fine and doesn't leak

 

[ronhic]

My mothers Sanyo died last year after 26 years stirling service.

I'll ask another question of you that you can ask your partner.

'If a wire came loose from the starter motor of your car of a similar age that you could fix by reconnecting it, even though the car is older, a little slower and possibly uses more fuel than when it was new (like the magnetron taking longer), would you plug the lead back in and continue using it or trade it because you're 'nervous' it'll happen again?'

Use it until it dies is my motto....especially if you like it. If my 15yr old Sharp dies tomorrow, even though a new one is cheap, i'll have to look into getting her sorted...

 

[little-edie]

my quasar is 30 years old. once in a while, it has a "hiccup" but otherwise continues to be a delight.

 

[autowasherfreak]

I have a Panasonic that a dear friend gave me when he moved to Chicago in 1994. I don't know how long he had it before giving it to me, but it's been a great microwave. The paint is starting to wear off in the inside a little, other than that no problems.

 

[launderess]

Though my Sharp is "newer" than yours (built in 2000), still had it repaired when it failed and was well worth the money IMHO.

In our case the unit wouldn't turn on because of a faulty door switch, which is a common problem. Years of opening and closing can wear the part out, and it is a safety feature to prevent the oven from operating with the door open. When we mentioned to the repairman that the unit didn't seem to cook as fast as it once did, they managed to get Sharp to cover the cost of new magnetron and a few other things as well under warranty, though the unit is long out of such.

Looked around at new microwaves before deciding on having this one repaired, and like much else in the consumer appliance world, quality of yesterday's models is streets ahead of what is on offer today. Most modern units are built in China or some other low cost part of Asia and though have tons of bells and gadgets, do not last more than several years on average. Not one single oven on display at local PC Richards or Best Buy had the heavy quality feel of my 2000 model year oven.

Replacing your unit is up to you. As others have stated there are ways to test for leakage, and if sound then I'd keep using the old rather than purchasing new. Also determine how you use the microwave. If you do nothing more than reheat items, pop corn, and perhaps cook small dishes such as veggies,then why spend several hundred dollars for a new oven?

 

[jeffg]

Thanks all for the info.

We had the same problem with it this morning, and I think we've narrowed it down to a failing door switch.

The door latches are fine, but there's a small switch with two very small spring-loaded contacts, and these seem to have worn out. So the oven thinks the door is open when it's not.

I'll try taking the switch off and cleaning it with some contact cleaner, and see if it helps.

 

[turquoisedude]

I would say keep the older one - you will likely be very disappointed with the quality (well, lack thereof) of a newer microwave.
I still use my 1986 Kenmore(the first appliance that I ever bought brand-new)and it works wonderfully!

 

[launderess]

Door Switch Part

Try some parts dealers or websites for a new door switch. The repair is common enough and if one knows how to go about it properly and safely, there shouldn't be any problems.

You can also contact Panasonic and see if the part is still available.

 

[jeffg]

I cut a small piece of electrical tape and wedged it between the non-contact side of the switch and the switch housing, so the door lever now depresses the contacts a little further into the switch.

Assuming that's the problem, hopefully it'll buy us another 20 years of service. If it doesn't work, I'll look into replacing the switch, or giving in to my other half and buying a new oven.

I could just tape down the contacts permanently, but that would allow operation of the unit with the door open. Not a good idea methinks.

 

[brisnat81]

Hi Jeff,

If you need to get a new one, the large Panasonic Microwave Convection ovens are still made in Japan.

We recently gave our 4 year old one to Mum and got a new one, and it proudly states on the box, Advertising stickers and just about the door switch, "Made in Japan".

Seems to be nice and solid, and not that different to Mum's 30yo National Panasonic that we just supplemented with the convection model.

In relation to Leakage, we had mum's old one serviced a couple of years ago, more as a check and the panasonic dealer stated that as long as your door still closes tightly and sits sqarely in the frame, you've got nothing to worry about, I cant remember the exact details, but it is supposed to be a 4 way seal on the door against the microwaves. All he ended up retrieving was a truckload of change that I'd inserted as a small child through the slots in the top of the microwave. Its been there for 25 years without causing any issues at all

 

[jeffg]

This is my first excursion into a microwave oven, and I'm extremely impressed with its quality of construction. Every wire is properly sized and harnessed, even the ribbon cable from the touchpad is thicker and sturdier than most ribbon cables I've seen.

The oven isn't particularly efficient, it draws 12 amps but outputs only 700 watts, but for some reason it's always performed like more powerful units (e.g. we follow package directions for 1100 watt ovens, and food is always properly heated). So I guess the magnetron is still in good shape. Our backup microwave is a much smaller, recent model Magic Chef, also 700W but it doesn't heat worth a damn.

 

[supremewhirlpol]

Microwaves are very interesting. If any of you ever get a chance, put a non usable cd in one and see what happens. Or better yet my favorite a lit candle, or a PAR Lamp or Metal Halide Lamp. Microwaves have big transformers in them that put out about 500V AC, Very fun. Also that capacitor in there has some good action to it also. The Magnetron has the strong magnets in it, but they are also good to chuck at people who really deserve it.

 

[roto204]

Woo-hoo!

CDs in a microwave? Guess what I did in college... ;-)

http://ftp.unb.br/pub/UNB/ftpfort/Fisica2/microwave_oven_experiments.pdf

 

[tolivac]

Microwave oven fans would like to log onto YouTube and Watch channels such as "Dovetastics Microwave Theater"and Is It A Good Idea to Microwave This?"they microwaved a Big Mouth Billy Bass-you have to watch to find out!also there is a channel besides Blendtec-"Can It Food Process?"The operator food processes various thenings-in "Shandor" the food processing Robot-actually a KA food processor.then after the itemed is "foood processed"its "Cooked" in a pan on a hotplate-kinda funny-glad the computer doesn't have "smellvision"!
If you do these microwave tests-I would get an oven from a yard sale or thrift store for these-don't use the one you use to cook food in.and if you like to experiment with the microwave oven parts--be careful with the capacitors and the transformer-The microwave transfomers have a secondary winding that can put out 500-1200V.Could give you a lethal shock.And the capacitor can store a nasty charge.And microwave oven transformers-at least most-have another secondary winding low voltage-high current to light the magnetron filament.I have put small flourescent bulbs and gas filled VR tubes in the microwave-but with a container of water in it too to provide a min load.the bulbs may not load the tube enough-could cause damage to the magnetron.Also microwave ovens have another safety switch in them to prevent the machine from running with the door open(Door monitor switch)-If you manage to bypass the first door safety switch-or its stuck closed-a fuse inside the oven will blow-generally a 15A cartridge fuse.This will prevent the oven from operating at all-dead.
I'll say this if the older oven is operating OK-keep it and keep using it.Newer cookers are getting less expensive-but the build quality is going down.Oh yes-at one time I did do experiments with an old microiwave oven magnetron-pulsed it with LV DC and it lit a small light held near the output probe-the glass upper part of the tube that projects into the waveguide that conducts the microwaves into the ovens cooking chamber.And just to think the microwave cooker came about from someone trying to cook something with a radar transmitter.

 

[whirlcool]

We have a Litton Model 412 that is in our garage still working. We bought it in 1976. However the glass plate that goes on the bottom exploded while Karen was cooking some microwave popcorn in a bag directly on the glass.

We have been totally unable to find a replacement plate for this unit. I heard there is a store somewhere that has a ton of microwave glass plates in stock, but I don't know where it is.

 

[everythingold]

I have a stack of Amana RadaRanges. They are great. They cook very evenly and look gorgeous. My oldest is a '74. BTW, early Micro's used lead shielding throughout. Aparrently, microwaves used to be dangerous. Now of course they are not, physics has changed, so no need for shielding anymore.

 

[turquoisedude]

Try this at Christmas...

Fill a clear glass bowl with water and float a few C7 or C9 bulbs in the water - set them in the microwave and turn it on to full power. The bulbs with twinkle on and off!
I think I still have the scar from where my mother whacked me upside the head when she caught me doing that in the family's old Litton-Moffat microwave in the late 70's! LOL