Our Panasonic combi microwave abruptly stopped working the other week. No lights, no nothing, and all the signs of a blown fuse. Swapping the plug fuse didn't help, so I guessed there might be an internal one - it being a model sold in markets with unfused plugs - and a bit of googling suggests there is.
I've found an online parts supplier and ordered two replacement fuses at £3 each (there's only one fuse but I'm paying a delivery charge so might as well have a spare in stock.) Question is, I know that microwaves also tend to contain a hefty and potentially dangerous capacitor. I have the means to discharge the one in mine - assuming I can find it - but I wonder to what extent it will have discharged itself after the appliance has been unplugged for two weeks.
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How long a capacitor stays charged for is one of those unanswerable questions as it depends on the type, the make and value!
Keep one hand behind your back if you are worried. I used to fix TVs and the LOPT (line output transformer) is a good one for biting you.
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Might not actually be any safer, but I always feel safer when messing with Electrickery things if I turn the plug upside down so that just the Earth pin is in the socket. It's almost become a routine now especially if i'm delving in the guts of a computer.
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>> Might not actually be any safer, but I always feel safer when messing with Electrickery
>> things if I turn the plug upside down so that just the Earth pin is
>> in the socket. It's almost become a routine now especially if i'm delving in the
>> guts of a computer.
Does this action serve any function?
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>> Does this action serve any function?
It means the appliance is grounded, but has no risk of the neutral and live still being connected. With things like PCs there is a risk of static discharge killing the ICs. Leaving the PC connected to an earth source helps reduce that static risk. I personally prefer to wear a wrist earth strap.
Quite how Devonite manages to fit the mains plug into the socket that way round is anyone's guess though.
If it were me, I'd just leave the mains lead connected and isolate it at the mains wall socket and also at the PSU. Providing of course you don't need to work on the PSU.
Last edited by: VxFan on Mon 6 Jun 16 at 12:47
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It will probably have discharged. They are designed to leak their charge over a few hours.
DO NOT TRUST THAT HOWEVER!!!!!
www.microtechfactoryservice.com/safety.html
Last edited by: CGNorwich on Sun 5 Jun 16 at 19:33
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Thanks chaps. I'll be careful in there.
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It will probably have discharged. They are designed to leak their charge over a few hours.
DO NOT TRUST THAT HOWEVER!!!!!
Which is why I answered vaguely... Having mended 300kW broadcast transmitters, you do get a sixth sense for such things, but they do have, inside the doors usually, an earthing wand with about five feet of insulating pole, a copper hook and cable good for about 100 amps. Standard practice to dab the earthing wand about before one contemplates touching anything. Power has to be off to get the door open in the first place - but has it worked right? One is decidedly cautious until you've proved it.
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I know that my daughter's erstwhile boyfriend, an very clever lad who knew what he was doing, mended a microwave. I wouldn't touch one with the back off, (a) because they can kill even when not plugged in (b) that has happened to people who mend them for a living. Clearly they must have ignored or failed properly to follow some procedural precaution, but it's enough to put me off.
I worked for an electrical retailer in the 1990s, when one of the service people was killed by a microwave on the bench discharging.
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It's knowing where to put your hands and where NOT to put them when you've got the cover off of a microwave or an old TV that has a cathode ray tube.
Anywhere near the HT section is a no no. Usually identified by something that resembles a big chunky lead. A bit like the HT leads that connect between the distributor and spark plugs on an engine.
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Here you can get pretty much anything repaired. Really anything.
But not microwaves. I'd previously wondered why, I guess this is the reaspn.
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To be honest since you can get a perfectly adequate microrwave for under £100 complete with a two year warranty for the most part they come under "disposable,not worth repairing category".
I think most people only use them for thawing out food and warming up meals anyway. Does anyone ever actually cook a meal in one?
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Depends what you call a meal I suppose. Very good for scrambled eggs, or pre-zapping a baked spud prior to finishing it off in the proper oven.
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Porridge is good too. A micowave is useful thing to have but I remember when they first came they were hailed as some work of miracle device in which you could cook an entire meal.
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>>I remember when
>> they first came they were hailed as some work of miracle device in which you
>> could cook an entire meal.
>>
A bit like pressure cookers in their day. Does anyone now use them?
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Yes. Steamed puddings and cooking beetroot.
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My mother, once tried to cook 3 haggis concurrently in a pressure cooker.
The result wasn't entirely as planned. It could, I suppose, have started a new interior design trend for the more adventurous...
Collaterally, two hot liquid haggis drenched dogs can also cause a lot of mayhem.
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>> Yes. Steamed puddings and cooking beetroot.
Good for soups too. Ours, like the Dyson vacuum cleaner, was something my Mother decided wasn't working.
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Soups is pressure cooker territory.
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>>Does anyone ever actually cook a meal in one?
Pasta.
Otherwise just warming up.
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>>Pasta
Yeah, they're ideal for spaghetti hoops, or a tin of ravioli.
;-)
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Like Runfer I've found it pretty good for scrambled eggs. Fresh fish is good too, or as a continuation of defrosting. Both though need to be removed before they're quite fully cooked, a minute or two stand time and all's OK. Eggs particularly are easy to overdo.
Mrs B stews fruit in it too.
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Melting cheese onto Staffordshire Oatcakes is another good one. .
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Interesting imagining of how they thought microwave cookers might look in the kitchen of the future c1959
blog.etsy.com/en/files/2013/02/microwave_of_the_future.jpg
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Whole root vegetables - a swede or a celeriac - work a treat. About 15 min, in a porcelain bowl to catch the ooze, then invert the root (not the bowl) and give it 10-15 more. The inside is then soft enough to scoop out with a spoon.
The rest of its time as a microwave it reheats frozen veg or occasional leftovers if I'm WAH, or it warms the teapot.
I disagree on scrambled eggs - they require close control and regular agitation, which is hard to do in a microwave. A 20cm Scanpan and lots of butter for those.
But our Panasonic is a combi with a killer trick - as well as, possibly, a killer capacitor: it can combine waves and warmth to produce four respectable baked potatoes - not wet paper bags - in 20 minutes. That's why we'll buy another if this one can't be fixed. It's also the only oven (of four in our kitchen) to have a timer-programmer, so it's handy for getting a hot pie ready to greet our return home.
Last edited by: WillDeBeest on Mon 6 Jun 16 at 18:07
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>> >>Pasta
>>
>> Yeah, they're ideal for spaghetti hoops, or a tin of ravioli.
>>
>> ;-)
>>
I bought a tin of Alphabetti Spaghetti for the kids.......I was annoyed when I opened it.....It only contained Os !
I'll get me garment !
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>> bought a tin of Alphabetti Spaghetti for the kids.......I was annoyed when I opened it.....
c5.staticflickr.com/9/8233/8461702140_b412eb7136_b.jpg
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>> Here you can get pretty much anything repaired. Really anything.
>> But not microwaves.
Nonsense ;) I repaired our old one twice, and my sister's as well.
The front keypads were dodgy on both of them (not at the same time). I initially repaired our old one (peeled the membrane back and cleaned the contacts), for it to fail again a couple of months later. I then sourced a replacement keypad for £10 and swapped it over. Several months later my sister's developed the same fault, but with a different brand of microwave oven. I replaced her keypad too.
I just made sure I kept away from the high voltage stuff, which was at the rear of the oven. The front panel was held in with 4 or 5 screws, and had a few multiplugs to disconnect from the PSU.
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For plate warming only.
Scrambled eggs cooked in one of those super dooper wipe, clean non stick frying pans. Mmmmm delicious.
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I repaired one. It was a resistor that had failed. Something like 100 ohms that had to dissipate a few watts so it got very hot. The build used a white, cement covered one, about 5cm long and about 8mm diameter --- the quality ones had green glassy finish, in my day, and would last the life of the equipment.
Did you actually test the fuse to see if it had blown?
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Yes, if your design says a resistor will dissipate one watt, you fit a five watt resistor. The rating assumes the resistor is in open space, anything nearby will reduce the rating. Bean counters though could well cause a one watt type to be fitted originally.
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If Busbee's fuse question was for me then no, I've not tested the internal fuse because that would entail removing the case and exposing the dangerous HV capacitor. But replacement fuses are cheap enough to order on the off-chance.
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>> I've not tested the internal fuse because that would entail removing the case and exposing the dangerous HV capacitor.
It'll only bite you if you go near it. Now stop being such a wuss and get to work checking for a blown internal fuse.
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Capacitors: how long does one stay charged? - Slidingpillar
