Whirlpool Combi-oven blows fuse, please help.

[Pier]

I have a Whirlpool combi oven/microwave that some time ago, when cooking rice with the microwave function blew a fuse and keeps doing so when plugged in.
No matter what setting the oven is on, door closed or open.

I've opened the device and there's a spark to be seen when plugged in, hard to tell where it comes from though.

(I think) i know it's not a problem with the outlet/fuse because the oven used to work on the same outlet before. (32A fuse)

I did a check on the internal fuses of the oven i could find and they had continuity.

After some google'ing i checked the door switches and they seem fine aswell. (continuity when pressed, none when open) All of the switched had some black oxidation? on one of the leads, but the others were clean.

The bottom mica plate has a hole burned through, the top one looks ok.


I believe it's a Whirlpool AM 220 BL (Vip 34 Crisp Series Forced Air Combi), but it's hard to tell because the sticker displaying wattage etc isn't to be found.
However, there is a sticker found on various parts of the device with two 12 digit numerical codes, accompanied by barcodes.
(8538 220 20491 & 37 9517 601113)
Whirlpool has a manual on their site for a model with code 853822020490. (AVM 220 WP BL)


My electronics knowledge is poor at best but i like to tinker/repair, so i've come here to see if anyone can/wants to help me out.
I can make pictures/video of the device if this helps.

[EDiT: added video]
Spark at ~11 sec, to the right of the thermoactuator


1) What else can i check with my basic multimeter?

2) Given the information above, where is the problem most likely to be found?

[diif]

Re: Whirlpool Combi-oven blows fuse, please help.

Photos always help.
Blowing fuses is usually something in the high voltage side of the power supply. Voltage rectifier, mosfet are usual suspects. The location of the spark is i feel a good stating point.

[Pier]

Re: Whirlpool Combi-oven blows fuse, please help.

Photos always help.
Blowing fuses is usually something in the high voltage side of the power supply. Voltage rectifier, mosfet are usual suspects. The location of the spark is i feel a good stating point.

I've added a video to my original post, and here's some pictures:
http://imgur.com/a/W1lKA

I was able to identify the red part to the left of the spark which is a thermoactuator (Eltek 100331.11 K T105 12), to the right of the spark is the magnetron itself?

[stj]

Re: Whirlpool Combi-oven blows fuse, please help.

microwaves are a great way for begginers to die - dont touch anything inside without asking!
i mean it, a lot of very experienced engineers wont work with microwave ovens.

[Pier]

Re: Whirlpool Combi-oven blows fuse, please help.

microwaves are a great way for begginers to die - dont touch anything inside without asking!
i mean it, a lot of very experienced engineers wont work with microwave ovens.

I'm aware that capacitors can have residual charge so i tried not to touch those..
What else is dangerous about microwaves?

[goontron]

Re: Whirlpool Combi-oven blows fuse, please help.

^ Well, it's not JUST the caps that will kill you. Unlike Flybacks, MOTs have more than enough current to kill you, and enough voltage to jump a 2 inch gap to do so.

240v mains at the US's 60hz is much more dangerous than the UK 50hz, so no gefingerpoken! You have decent current available on the mains to start a fire, (Those two are combo unit specific) and of course Microwave radiation around 1kw.

[Pier]

Re: Whirlpool Combi-oven blows fuse, please help.

^ Well, it's not JUST the caps that will kill you. Unlike Flybacks, MOTs have more than enough current to kill you, and enough voltage to jump a 2 inch gap to do so.

240v mains at the US's 60hz is much more dangerous than the UK 50hz, so no gefingerpoken! You have decent current available on the mains to start a fire, (Those two are combo unit specific) and of course Microwave radiation around 1kw.

It's 240V @ 50Hz here afaik.

But a transformer doesn't store electricity, right? So as long as it's unplugged i should be relatively safe?

I'm currently taking the machine apart, and i'm not plugging it in until i know i've fixed what was faulty.
Either that or it's going to the dump.

In the last picture it looks like the middle relay is burned and the inside copper contacts melted together, could this make sense?

[sam_sam_sam]

Re: Whirlpool Combi-oven blows fuse, please help.

In the last picture it looks like the middle relay is burned and the inside copper contacts melted together, could this make sense?

Yes the one in middle is looking bad and one on the right side it hard to tell what shape it is as well

Take a real close look at both of the also check the two heating elements for short and open

In all of the photos I do not see the high voltage transformer please take of that transformer

Thanks

[goontron]

Re: Whirlpool Combi-oven blows fuse, please help.

It's 240V @ 50Hz here afaik.

But a transformer doesn't store electricity, right? So as long as it's unplugged i should be relatively safe?

I'm currently taking the machine apart, and i'm not plugging it in until i know i've fixed what was faulty.
Either that or it's going to the dump.

In the last picture it looks like the middle relay is burned and the inside copper contacts melted together, could this make sense?

Oh, Belgium... Heh, yep. That's 50hz....
That's if you have to any measurements with it running, otherwise, yeah, its just the cap.

That relay does look like it's splattered to hell, i suppose if its part of the interlock and welded closed that could very well be the problem.

[petehall347]

Re: Whirlpool Combi-oven blows fuse, please help.

that arc is rather large .. lots of volts there i guess .. seems to come from the part in the middle . transformer/coil looking thing ,

[Pier]

Re: Whirlpool Combi-oven blows fuse, please help.

Yes the one in middle is looking bad and one on the right side it hard to tell what shape it is as well

Take a real close look at both of the also check the two heating elements for short and open

In all of the photos I do not see the high voltage transformer please take of that transformer

Thanks

Thank you.

I took some more pictures including the transformator:
http://imgur.com/a/fOKH7

The quartz grill has continuity, i'll check the heater for the hot air tomorrow.
I'm thinking about desoldering the relays from the board so i can have a better look at them.

[Pier]

Re: Whirlpool Combi-oven blows fuse, please help.

Oh, Belgium... Heh, yep. That's 50hz....
That's if you have to any measurements with it running, otherwise, yeah, its just the cap.

That relay does look like it's splattered to hell, i suppose if its part of the interlock and welded closed that could very well be the problem.

I only know how to measure DC voltage, resistance and continuity. I've got my hopes on the relay too.

that arc is rather large .. lots of volts there i guess .. seems to come from the part in the middle . transformer/coil looking thing ,

I think it's coming from behind the transformer in the middle, where the cavitation chamber (waveguide?) for the magnetron is.

The part with the transformer is the ventilation fan, could that even produce such a spark?

Thanks.

[goontron]

Re: Whirlpool Combi-oven blows fuse, please help.

BTW, what you have pictured isn't a cap. This is.

[stj]

Re: Whirlpool Combi-oven blows fuse, please help.

you know, if it's blowing external fuses but not internal ones - it could be a shorted capacitor inside the mains-filter can behind the incoming power cable!

[goontron]

Re: Whirlpool Combi-oven blows fuse, please help.

^yeah, that had me a tad confused as well.... You would think the board fuses would have gone.... Could also be bad cable insulation tripping the RCD though... Like where it was arcing...

[stj]

Re: Whirlpool Combi-oven blows fuse, please help.

most people dont have a pat tester or a megger though.

[Pier]

Re: Whirlpool Combi-oven blows fuse, please help.

BTW, what you have pictured isn't a cap. This is.

I don't know exactly what you mean by "what you have pictured"
Yes, the one you circled is a filter cap for the magnetron and slightly to the right is another filter cap for the quartz heater and hot air element. (that's the main's filter?)

you know, if it's blowing external fuses but not internal ones - it could be a shorted capacitor inside the mains-filter can behind the incoming power cable!

This one?


Can i test this cap when it's removed from the device?

^yeah, that had me a tad confused as well.... You would think the board fuses would have gone.... Could also be bad cable insulation tripping the RCD though... Like where it was arcing...

The main's RCD doesn't trip, just the fuse of the outlet i'm using for the oven.

The only cables i can see that have somewhat damaged insulation are going from the transformator to the magnetron and magnetron filter cap.
But they're still fully insulated even though they've shedded some skin. (don't know how else to describe this)

most people dont have a pat tester or a megger though.

I have just a basic multimeter, no pat tester and/or megger.

[stj]

Re: Whirlpool Combi-oven blows fuse, please help.

you need to attach photo's from the advanced option.
i cant see anything you liked from another site.

[Pier]

Re: Whirlpool Combi-oven blows fuse, please help.

you need to attach photo's from the advanced option.
i cant see anything you liked from another site.

I don't know why you can't access imgur but i've added some pics as attachment.

[stj]

Re: Whirlpool Combi-oven blows fuse, please help.

3bad relays,
cracked soldering on the pcb,
signs of water damage that needs to be investigated.