Component failure

Common mode choke, for EMC compliance. Helps stop electrical noise getting out.

Cheers

Choke took the brunt of the flames, but I think the source of ignition was a rectangular Class X capacitor below the choke.

Yes, you'd need a hell of a lot of current for that choke to burn itself.

Cheers

Or possibly a component afterwards that has burnt beyond recognition. A poorly rated capacitor or suppression device (Metal-oxide varistor, MOV).

The toroid looks like a choke but that doesn't look like the bit which fried, although it has been scorched that seems to be due to the part next to it.

That looks like a capacitor, which makes sense as the whole assembly looks like a filter.

Brian Reay wrote in news:pivrfs$709$ snipped-for-privacy@dont-email.me:

Realistically - I believe it would soon burn itself out. Would you agree?

Many years ago, I had some Wima Capacitors going bang catching fire and all sorts including making black smoke.

There were three normally across both, so 6 in all of a choke to make a mains filter. You could not actually prove it, but I suspect the mains had surges or spikes. I do have nowadays some VDRs that are supposed to stop this sort of thing, and they do seem to have worked, but then its awfully hard to prove a negative result! Brian

Had one blow in a 37 year old Sharp amplifier recently. Filled the living room with an acrid stench.

I opened my dishwasher when drain pump stopped working. Unrelated to that, I found the mains supressor had blown up at some point in the past and left a long scorch mark up the plastic back. Like the one in the picture, it's fitted as an extra part for some countries only, and thus powered permanently, rather than being properly integrated into the product. It had blown itself out of the circuit without blowing the fuse, so this went unnoticed at the time.