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Microwave Interal Fuse Rating Unknown

Our Luker MW 17 SV1 microwave stopped working. All panel indicators are dead. Power lead fuse (standard domestic 13A) is good as is the supply voltage. Internal ceramic cartridge fuse (32 mm long) has blown. Frustratingly, there are no markings on the fuse so I don’t know what Amp rating it is - nor whether it is a slow-blow type. Circuit diagram is no help as also does not show any component values. This single fuse is located on the mains power board (Noise Filter) but again there is nothing to indicate the component value. This pcb has 3 identifying stencil labels. These are: a) DNV-0818A b) TC 6081B 02 1029 c) TC - 368 94V-0

After several fruitless hours of web searching I stumbled across your site and would be immensely grateful if someone can provide me with this info. Regards Chris

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Hi @chris230 ,

According to this link (search for DNV-0818A in the catalogue), a DNV-0818A-5 has a GEV part number of 403188

When zooming in it shows that the fuse is a 250V 12A. (see image below)

There is no mention of T or S (timed or slow - means the same thing) on the board’s fuse rating so it must be a standard fuse i.e fast acting.

Be aware that there is always a reason why a fuse blows so maybe order two or three as you might have to find out why it blew.

Be safety aware when working in microwave ovens. The HV capacitor can store >5000V DC for months even if the power has been disconnected for this length of time. This amount of voltage can seriously injure you. The capacitor needs to be discharged correctly before doing any further work in the microwave oven. Apologies if you knew this already

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Thanks a million jayeff. It is a constant source of irritation to me that I cannot find what I am looking for on the web but that someone else can.

Thanks also for both your warnings; why fuses blow and capacitor voltage. I'm an ex-RAF electronics techie so am aware, but full marks to you for mentioning them because you didn't know that. Thanks again, Chris

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@chris230

Know the feeling ;-)

The usual suspects when a fuse blows in a microwave oven are the door interlock switches ( usually there are 3 separate micro switches, 2 x NO and 1 x NC with the door open - either broken actuator, loose mounting bracket or contacts welded i.e short circuit), faulty HV transformer (short circuit) or faulty HV diode.

Of course this is not to say that it isn't something else either in the wiring or on the user control board

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Hi jayeff, closer examination of my original fuse link end cap shows it is 8 Amp.

I have owned this m/w from new so this fuse is original. I can only assume that these circuit boards are used in a variety of products and may have different ratings of fuse fitted depending on their use.

After more difficulty finding 32mm fuses, I finally laid my hands on some slow blow thermals. Although only 5 Amp, I wasn't concerned at using them as with a lower curent rating they would readily blow if there was indeed a fault elsewhere in the device.

Various tests, from low to high power, all gave the expected results so I am calling this a sucessful result.

I supect that the original fuse failed as a result of age and long use - as you too no doubt know fuses, and other components, will sometimes do this. I shall, however, continue to seek out replacement fuses of the original rating because that is the right thing to do.

Thanks for your help

Chris

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@chris230

I agree about the rating.

The same board can be used in various devices but the one I linked was the only one I found that showed a rating, the rest were painted over and illegible.

I assumed that since it had a lower rating than the household supply fuse, it would blow before it did and therefore wouldn't damage anything outside the oven and hopefully would also blow if there was a fault in the oven.

Are these what you need? Only problem is you have to order 10. You could try searching for "Littlefuse 0314008 mxp" and see what results you get. the best I managed was minimum of 10

Cheers

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Yes, them's the critters. But I see your link is from Australia so will probably give them a miss as I am in UK. Not looked yet but am sure they will be readily available on line. I was just miffed that I couldn't just pop in to an electrical retailers and buy one. No body in my town seems to sell 'em, and local small electrical repairs companies also seem to have become a thing of the past.

Pleased to see you found our conversation useful meeda madee.

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Chris Stevens crwdns2893898:0crwdne2893898:0
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