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Microwave Oven with Digital Timer using Inverter/Travel Power


Tony Fuller

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Hi all elecronic specialists.

After some 20+ years of reliable service our Sharp Microwave/Oven/Grill has finally given up.

We are a 'gas free' boat with a 2500 Watt Heart Interface Inverter/Charger & an Elecrolux Travel Power engine driven generator.

Boat has some 1000 Amps of battery supply.

Looking to replace this, I find that today 99% of all Microwaves have Digital Timers.

My question is, will the digital timer work OK with the 'chopped waveform' from the Heart Interface, also what is the Waveform from the Elecrolux Travel power unit & how will this respond.

Has anyone had experience with digital timer microwaves using these power sources.

Also does anyone know of a Microwave/Grill Combo with an analogue timer. (I have only found one a Bosch HMT72G450B with a manual timer but this is a bit on the small side.)

I look forward to hearing your views & experiences.

Thank You

 

Tony

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Know nuffin about the Heart stuff but the TravelPower makes a good clean and stable sinewave.

There are two possible TravelPower issues. Its not 240v but two lots of 120v but this is very unlikely to cause problems. The bigger issue is that the voltage can potentially drop quite a bit at very low revs/tickover and it aint that high to start with. Ours is 229 to 230 rather than 240. Most electronics should be ok as they are probably exported to parts of the world with poor electricity anyway. Dn't use the big hairdrier whilst the microwave is on.

 

.................Dave

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Strange,

 

Last week house microwave went 'pop' resulting in a rapid trip to Tesco's for a replacement (6 pm on a Saturday) My impression was that there were several manual models available. Indeed, I considered getting one for stock for the boat but sense prevailed.

 

Frank

 

Read original post again. The ones's I lookked at may not have been combos'

Edited by Slim
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Thanks Dave,

 

I know that the Microwave did run better on the Travel power, however I don't really want to start the engine to heat up a jug of hot milk for my cornflakes in the morning (this stems from childhood days with frost on the insides of every window in the house)

A quick 1 min blast using the inverter always did the trick. However that may not work with the 'chopped' waveform & a digital timer

 

Thanks Slim.

Yes I have found a few solo microwaves with anologue timers but very few Combi units with grill/Oven. We do need this to 'brown' the topping on the cottage pie !!!

 

Anyone else with ideas or first hand experience of what happen to digital timers when using a 'chopped' or 'modified sign wave inverter'.

Do they (a) Blowup (B) Refuse to work © Just flash & go crazy (d) All or non of the previous

Look forward to learning of your experiences.

Thank You

 

Tony

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Good idea, never thought of that, kettle could get a bit 'milk skinny though'.

Any other sensible suggestions.

Thanks

OK a jug and a travel boiler it would take care of the early morning hot milk http://www.ebay.co.uk/itm/like/351790910762?lpid=122&chn=ps&adgroupid=27378760866&rlsatarget=pla-181484324226&adtype=pla&poi=&googleloc=9044897&device=c&campaignid=620865095&crdt=0

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Umm - unless it's something *** obvious it's nowt to do with the timer being electronic or not, it's more that older units with a clockwork timer might be likely to use a transformer to get the high voltages for the magnetron (that's what does - or did - the microwaves). Modern kit has to be light (costs-a-lot to ship heavy stuff from China) and anyway it's cheaper to manufacture a switch mode power supply than it is to wind a transformer.

Soo - anything recent will be light and have a square wave-unfriendly power supply. Especially combies which need more sophisticated electronics.

My first micro: was huge (and the compartment small) and weighed 'a ton'. My current machine is small and proudly says it's digital....

 

Bite the bullet and run the engine - or change your lifestyle. I come from the days when boating was akin to camping - so I have little sympathy.

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Hi Old Goat

Yes you are right about the weight, like yours our old unit also 'weighed a ton'. I opened it up to see if a simple repair could be made, but it was the magnetron that was u/s. It did, as you say have a big heavy transformer.

To be honest I didn't realise that the modern units had a 'switch mode power supply' which could cause trouble.

I don't think that the Combi microwaves need to have 'more sophisticated electronics' as all they are is a standard microwave with a built in heater element/grill.

I might try contacting the Manufacturer to get their advice on using 'modified sine wave' electrical supply. I suspect that they will say 'NO' automatically.

Have any members on this Forum actually tried running a modern digital timer microwave on a 'modified sine wave ' inverter, if so how did you get on please.

Thanks

Tony

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Hi Top Cat

When your Bread Maker failed when using a quasi sine wave supply was it the 'digital timer' that failed/melted/ or/blew up or did it have a 'switch mode power supply' inside which caused the smoke, or did you just scrap it without opening up to see what had happened.

Just trying to get to the bottom of potential problem

Thanks

Tony

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Sorry Tony I didn't take it apart, but it totally failed in that nothing worked at all ( I had tested it at home) after going on the inverter. Putting it back on real mains at home didn't fix it.

I suspect that there was a switch mode power supply in it to get the low voltage DC for the timer and a tyristor drive for the motor. It wasn't very heavy so I doubt it used a transformer.

My new TV flat screen also sulked but wasn't permanently damaged. I did take the TV apart much later and found a transformer based power supply.

 

hope thats of some help

 

Top Cat

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My mum had the same 1/2 tonne sharp for many years... when hers went pop last year i found an identical one at the local "tip" shop ... paid 12 quid for it with a 3 month guarantee and it had even been P.A.T tested , 12 months on its fine , so if you have anything similar i your area take a look you would be surprised ! ... at the same time bought a normal digital one for my nieces flat and that was 6 quid! although used both are like new .....

 

Rick..

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Tony Fuller, on 04 Nov 2016 - 9:40 PM, said:

Hi Old Goat

Yes you are right about the weight, like yours our old unit also 'weighed a ton'. I opened it up to see if a simple repair could be made, but it was the magnetron that was u/s. It did, as you say have a big heavy transformer.

To be honest I didn't realise that the modern units had a 'switch mode power supply' which could cause trouble.

I don't think that the Combi microwaves need to have 'more sophisticated electronics' as all they are is a standard microwave with a built in heater element/grill.

I might try contacting the Manufacturer to get their advice on using 'modified sine wave' electrical supply. I suspect that they will say 'NO' automatically.

Have any members on this Forum actually tried running a modern digital timer microwave on a 'modified sine wave ' inverter, if so how did you get on please.

Thanks

Tony

From the user's point of view - the extra combi features appear to be simple. BUT to control the extra features - "select this and that", set functions and so on would require more complicated switches and so, so it's cheaper and less bulky to go the whole hog and 'digitise' the whole lot.

 

At least my internal assumption that your old unit was of the 'steam driven' variety - and that's why it worked on an MSW inverter.

With electronic kit an appliance maker will buy in the electronic bits from a very few suppliers who themselves will use standard components, so the chances of finding a modern unit that will work for you are very limited.

As others have said - try to find an old used unit, run then engine, or even change your mode of operation....

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Hi OldGoat,

Thank you for all your help, I have been doing a bit of internet surfing (mainly among the RV & Sailing Forums) & the general consensus is that using a modified sine wave inverter is usually OK (but slower which i already knew) but any with digital clocks can give problems.

My idea was to look for a microwave/grill unit with a 'clockwork timer & a transformer powering the magnatron.

As you so rightly say it may be that the cheaper/smaller Microwaves are powered by 'switch mode power supplies' which will not like the MSW supply.

I will have to try to get more detailed specifications on suitable units before parting with any money.

I probably won't be using this until next year so I have got a bit of time for searching, but if a suitable unit did come up I will grab it as these will now be quite rare.

 

Hi dccruiser

Yes mine was an old heavy Sharp unit (ran for 25 years) which I disposed off at our local council skip centre. They do have an appliance re-cycling centre but this all goes to charities & is not for purchase by the general public.(Usually they won't sell used Electical Goods even to charities due to 'health & safety issues')

I now wish I had held onto my old microwave & try to get it repaired ( but I assumed that spare parts would no longer be available). Its gone now so I will have to continue my search for a suitable unit.

Do any other forum members have a microwave running on a 'modified sign wave inverter' please ?

Thank you all for your help

 

Tony

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