Dead Microwave

Our elderly (10 years?) microwave appears to have died.

Used it at lunch time and left the door open as there was a bit of smell inside.

While having lunch I thought I heard a slight banging noise from the utility room, but I may well be mistaken.

Closed the door earlier, and no sign of life - display completely dead (usually shows the time or remaining time if stopped mid programme).

Socket working, and fuse in the plug also intact.

I would rather keep this one if possible - new ones seem cheap as long as 800w, and much pricier for a similar 900w. Also it is a 28L one, and he new ones at a reasonable price are much smaller (20 or 23L).

Any thoughts as to what to look at next?

Reply to
JoeJoe
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Be very careful. The transformer in those puts out approx 2000V and there is a large capacitor in them to smooth out the high voltage DC. Basically Microwaves offer plenty of ways of killing yourself if you don't know exactly what you are doing.

Might be a lot better to just pick up a new one, they don't cost very much these days anyway.

Philip

Reply to
philipuk

So could be the transformer but still the microwave diode bit could be the failure, and you can't just buy them.

Polotergiests, aliens ;-)

so proppbly a power supply failure.

You might be able to get it repaired but they aren;t easy unless it is a simple fault. But can be quite dangerous to fix or mess with.

new ones seem cheap as long

A good repair shop that knows what they are doing. There also might be a reason if suddendly failed, then there's the problem of uw leakage with old ovens so it could have been drawing more power. We had one here taken apart and used in an experiment internal 10 amp fuse kept blowing because until we encased it better.

we have a microwave lab and a leak detector and we had it checked out so there was no danger as no one was alllowed in the room while it was on.

No where near as much fun as the 6.6MV generator we did have. :-(

Those were the days when we could really generate a few sparks.

I wouoldn;t attempt a reapir due to uncertains of whether it was safe.

Reply to
whisky-dave

Thanks guys - got the message - time for a new one.

The Mrs just walked in and reminded me that we bought it to warm up the bottles for the little one a few months after she was born. She is now in secondary school, so can't complain really...

Thanks again.

Reply to
JoeJoe

At that age, the door safety interlock (a pair of microswitches) could have worn. The normal circuit design for this is that if the interlock microswitches disagree if the door is open or not, they are connected such that they short out the mains supply and blow an internal fuse, rendering the appliance completely dead.

Fixing this is not just a case of replacing the fuse - door alignment and wear on hinges and catches needs to be checked and parts replaced if necessary, and the interlock microswitches should be replaced once they have been used to crowbar the supply.

Reply to
Andrew Gabriel

whisky-dave wrote in news: snipped-for-privacy@googlegroups.com:

Perhaps a fuse on the circuit board. Take care though.

>
Reply to
DerbyBorn

Burning chemical non-food smell, or badly done curry or pizza?

Could be moisture settling somewhere shorting out things (did the fan work?), or erm, flames...

Panasonic 'inverter' brand are known for going bang with gusto. I'm waiting for ours to do so.

I'd do a (careful) autopsy out of interest, but certainly buy another.

Reply to
Adrian C

Probably best to replace with new. Repair may be possible but at what cost. If you are going to scrap it, the magnetron contains at least one rather strong magnet. The casing and innards have a multitude of useable self tappers. The timer and bell are good also. Rotating platter. Loads of re-useable stuff. Our microwave, Sharp Carousel II combination thingy, is 30 years old. Used several times each & every day. Cooked an entire Christmas lunch with it years ago after Paddy decided to dig through the gas supply on night of 24 December.

Nick.

Reply to
Nick

Display dead suggests main fuse most likely. Sometimes these blow due to a 1 off short term interlock fault, sometimes the interlock is cooked. If you replace the fuse, you MUST check the shorting resistor and ensure its replaced if not working.

There are sometimes fatal voltages inside. Know what youre doing first.

NT

Reply to
meow2222

I used to have one that would regularly blow the internal fuse (which covered everything), but that would always happen when it kicked in with a bit of a thump (presumably a surge through a hefty relay or somesuch). Maybe you can get a similar effect when it stops too. Last time it happened, I couldn't track down a new fuse easily so decided that it had earned its money and got a new one.

Reply to
GMM

Pah! That's not 'elderly'! I'd say it was a case of 'infant mortality'. I had to retire our venerable 22 year old Toshiba ER-7700E

9 months ago on account the display had developed a habit of fading out which seemed to due to an intermittent high resistance contact since a playful slap on its flank would revive it.

In all other respects, it was still working perfectly. In spite of daily usage over the past 22 years it's efficiency was only about 2 or

3% down on a Sainsburies stainless steel special we'd bought as a cheap replacement (a mere 40 quid less another fiver to compensate the inconvenience of returning it for a replacement on account of cosmetic damage to the plastic door trim).

Unfortunately, I wasn't able to fix the fading display issue on the Tosh otherwise I'd have reinstated it in pride of place in the kitchen to replace the bleeping SSS Special (5 feckin bleeps - 3 bleeps were more than enough with the Tosh but at least the cancel button would let you cut the surplus beeps off, unlike the dammned SSS Special which used a Magnus Magnusson bleep algorithm).

Apparently the SSS Special was better than most other ovens costing 2 and 3 times as much according to my brother and SiL who'd spent some time tracking down this little gem (only 20L versus the 27L of the Tosh which also had the advantage of a door with a proper release handle and an opening angle of 120 deg instead of the woefully inadequate 90 degree of the SSS Special).

The only plus point with the SSSS was the use of a knob to increment the cooking time selection with varying steps, similar to the much better implemenation of this control executed by the Tosh designers (freewheel large knob with end stops versus detented knob with no end stops- you could instantly select the maximum 95 minutes by going one notch backwards and count down in the larger increments if trying to program 30 minutes or so, nice idea but the time saved in setting was so marginal as to not be worth the downside this involved - if it had been considered by Toshiba, I could well imagine it being rejected as "A Stupid Idea").

I've still got the Toshiba parked up in my 'Stock Room'. I might have another look at the control/display panel but I doubt it. I'm hanging onto it as a spare for when the SSSS goes bang just outside of its warranty as modern day appliances are wont to do.

Possibly the controller PSU transformer insulation overheating or maybe an smpsu HT smoothing cap drying out and overheating if you had indeed heard a slight banging noise as per your comment below.

Quite frankly, before you figure out how to remove the protective cover, I suggest you look at for details on MO repair and take heed of the warnings regarding the very high voltage high current supply (some 4KV or so when operating with the possibility of 2KV stored on the voltage doubling capacitor if its safety resistor has gone open circuit, even when switched off).

The magnetron EHT supply can kill you stone dead in an instant if you poke any fingers into the wrong place whilst it's operating. You may want to rethink about attempting a DIY repair.

When I was working on the Tosh, I was all too well aware of the hazard but I was able to stay well clear of the dangerous bits when checking out the controller board and its connectors (I was _only_ concerned with an intermittent display fault - the oven still cooked food just as it always had so there was no need to go poking around the magnetron and its EHT supply).

Reply to
Johny B Good

It is pining for the fjords.

Reply to
Nightjar

One supposes that as it was, at the time just sitting there with its little internal light on that it could have just blown short circuit and taken out a fuse removing power from the unit.other than that I'd be very very careful. I had mine appear to be dead about a week ago, but it was just confused, as when I unplugged it and plugged it in again it sprang back to life.

Mine is a Cobolt with peech, but I'd bet te actual guts are much the same as others.

Brian

Reply to
Brian Gaff

Only 22? Our Toshiba is 34 now and has no truck with stinking beeps. It "dings" just like a proper microwave should. ;-)

Tim

Reply to
Tim+

Our Belling is about 40, had to recap it about 10 years ago, it has a genuine low power setting and yes, it dings!

Reply to
Capitol

I was being conservative in my estimate, it might well be more like

27 years (I can't recall a time when we didn't have that Toshiba MO in the far corner of our 30 year old kitchen extension).

I can only surmise that our attempts at creating a famous Chinese dish lacked a certain "je ne sais quoi" due to those "steenking beeps". I can well imagine you enjoying a dish of "Chicken Ding!" as often as you fancied. :-)

Reply to
Johny B Good

I so want this Black & Decker oven ...

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Reply to
Adrian C

Sometime up to the early 80's to obtain BEAB approval for a microwave, it was stipulated that there was to be *only* a single interlock switch on the door, directly actuated via the hinge I believe. Additional switches could be fitted such as on the latch but there were limitations on what direct 'safety' functionality these switches could provide, presumably the hinge switch was on the supply to the transformer, whilst those on the door latch possibly disabled the timer.

(I only heard this secondhand many years later but have next to zero doubts about the accuracy of my source)

Reply to
The Other Mike

safe in that respect. 70s nukes use a simpler arrangement where some failu res blow a fuse, some expose the user to cooking power.

power until the door was part way open.

The 1960s machine I checked had only a hinge-side switch, an arrangement th at inevitably results in a degree of opening before cooking is stopped. On this machine it opened by 20 - 30 degrees while still cooking. I advised th e owner it was too dangerous to use or sell. It must have cost a fortune wh en new - I remember one costing £400 in the 1970s.

NT

Reply to
meow2222

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