New build with recycled parts on a ridiculous budget 120cm*60cm work area

[m_c]

There's a reason transformer manufacturer's usually recommend slow blow/time delay fuses, and this thread has just proven why.

Fit a 10A MCB to a 1KVA transformer, and there is a high probability the transformer winding will fail before the MCB trips.
1KVA roughly equals 4 amps, so taking a type B MCB, it takes a minimum of 6 seconds at double the rated current for it to trip. So taking that 10A MCB, that's 20A, 5 times the transformer rated current, or over 4KW flowing for 6 seconds. Do you still think that MCB will do much good?

I personally just use a time delay fuse rated around 120% of the transformer rating. If you blow it, you're doing something majorly wrong, and it's far cheaper than a MCB.

As for cheap multimeters, they rarely have a fuse for the amp setting, which is likely what will of caused the problems. A sudden short on the power supply, as well as causing the transformer to fail, will of likely burnt something out in the power side of the AM882. If you were to strip it down, you could at least check the main power supplies are still functioning.

Also, if you strip the outer covering of the transformer, you might find the fuses near the outside of the windings, so it could potentially be a relatively easy repair.