Id this fuse

[BrokenBiker]

Black component bottom right of the board, labelled only as F1 and appears (although there are no visible tracks to or from either side) to be the main incoming fuse...it is soldered on one end right next to the live 240v ac and the other end has a resistor labelled 1004 and measures at 920k ohm on my admittedly amateur meter...

Component F1, that i have to assume is a fusible link, is showing no continuity, OL on resistance...haven't tested it hot but can if needed although being Chinese im not too keen to get where near it when its plugged in

Question is, what value fuse do I need?

Its an 1100w induction heater board from a hand held nut buster type heater. 240v AC raw into it at this point, rectification happens afterwards from what I can see.

I'm not fantastic with electronics, but I can solder and do basic testing

Edit, looking st the photo I can now see there are tracks, although difficult to see by eye...fuse is definitely connected to main 240v brown wire, and then the fuse mentioned which then goes on to feed the torroidal transformer, that then feeds back to neutral on the 240v

 

[BrokenBiker]

Ok, got the fuse off the board with more effort than should be needed, they appear to have bent the legs though the board before soldering...I can now see it has 5A written underneath...does that seem reasonable for something like this?

 

[Seadog]

haven't tested it hot but can if needed although being Chinese im not too keen to get where near it when its plugged in

You're Chinese?

 

[Guineafowl]

Is there heat shrink over the fuse? Cut it off and see if there’s a rating on there.

5A would suggest a power input up to 1.25 kW or so into the board. Sure it’s not .5A?

 

[Mark 5]

Is there heat shrink over the fuse? Cut it off and see if there’s a rating on there.

5A would suggest a power input up to 1.25 kW or so into the board. Sure it’s not .5A?

That was my thinking.

 

[BrokenBiker]

Is there heat shrink over the fuse? Cut it off and see if there’s a rating on there.

5A would suggest a power input up to 1.25 kW or so into the board. Sure it’s not .5A?

Nothing to be seen under the heat shrink except a glass tube. No markings i can find.

It states 5A/250 on the board under the fuse. I didn't get a photo and have now put the case back together but it was definitely 5A

I have found a batch of 10 fuses that mach those specs and look identical for 15 quid which gives me confidence.

Strangely, this 5a fuse is fed directly from the plug...but the plug has a 13amp in it

 

[BrokenBiker]

You're Chinese?

Can confirm

 

[voipio]

5A would be the current drawn by a 1150W resistive load off 230V, so slightly under-rated for an 1100W induction heater.

 

[Guineafowl]

Nothing to be seen under the heat shrink except a glass tube. No markings i can find.

It states 5A/250 on the board under the fuse. I didn't get a photo and have now put the case back together but it was definitely 5A

I have found a batch of 10 fuses that mach those specs and look identical for 15 quid which gives me confidence.

Strangely, this 5a fuse is fed directly from the plug...but the plug has a 13amp in it

Could be, then. The only other rating would be fast or slow blow (F or T written on the fuse, usually). Fast tend to be a plain wire, slow a sort of coil/filament.

13A to protect the flex, 5A to protect the board.

 

[BrokenBiker]

5A would be the current drawn by a 1250W resistive load, so maybe slightly under-rated for an 1100W induction heater.

What would you suggest? I can get 5a fuses as a direct replacement.

In its defense, there is a sticker that says 90 sec max continuous load...I may have been trying to anneal a 16mm diameter rod and had been at it about 6 minutes when it let the smoke out

 

[Guineafowl]

You could solder some leads onto a 5A plugtop fuse and bodge that in. Or, bridge the fuse and fit a 5A into the plug. Just to get you going till the replacements turn up. But you didn’t hear that from me

 

[voipio]

Not sure about the exact type of fuse being used on that PCB but, based on other small fuse types, the next higher current preferred values are likely to be 6.3A, 8A, and 10A. I'd be inclined to go for 6.3A.

 

[BrokenBiker]

You could solder some leads onto a 5A plugtop fuse and bodge that in. Or, bridge the fuse and fit a 5A into the plug. Just to get you going till the replacements turn up. But you didn’t hear that from me

That idea did cross my mind if im honest

 

[BrokenBiker]

Not sure about the exact type of fuse being used on that PCB but, based on other small fuse types, the next higher current preferred values are likely to be 6.3A, 8A, and 10A. I'd be inclined to go for 6.3A.

Will see what's available

 

[BrokenBiker]

So...just tried bridging the duff fuse with length of wire just to see if there is any glimmer of hope in reviving it...blew a 5amp in the plug as soon as it was plugged in (without pressing the button) and I cant understand why as ive tested everything on that side of the circuit and it all seems to check out with what I would expect...but the moment its plugged in it either blows the fuse or trips a breaker...

So unless anyone wants a project, its for the bin

@JOEPRO want a bare induction heater to play with? All ive done is solder a wire in place of a fuse

 

[Guineafowl]

So...just tried bridging the duff fuse with length of wire just to see if there is any glimmer of hope in reviving it...blew a 5amp in the plug as soon as it was plugged in (without pressing the button) and I cant understand why as ive tested everything on that side of the circuit and it all seems to check out with what I would expect...but the moment its plugged in it either blows the fuse or trips a breaker...

So unless anyone wants a project, its for the bin

@JOEPRO want a bare induction heater to play with? All ive done is solder a wire in place of a fuse

I wouldn’t mind a project, if you’re willing to post.

 

[BrokenBiker]

I wouldn’t mind a project, if you’re willing to post.

Send me an address and ill find a box. It will only have 1 element with it as ill be buying a new one so will keep the old elements, but its only a bit of 2.5mm single core copper really

 

[Guineafowl]

Send me an address and ill find a box. It will only have 1 element with it as ill be buying a new one so will keep the old elements, but its only a bit of 2.5mm single core copper really

Cheers. If I manage to repair it, I’ll post details.

 

[eddie49]

fuse is definitely connected to main 240v brown wire, and then the fuse mentioned which then goes on to feed the torroidal transformer, that then feeds back to neutral on the 240v

I think that is an inductor with two windings, rather than a transformer. Part of the input mains filter:


The fuse is probably blowing because there is a shorted MOSFET or IGBT in the inverter.