[e-merlin]

The Delta Blues is an EL84 amp right? Peavey Classic series?

It will have both the mains fuse and a couple of other fuses inside the chassis. You will need to drop the chassis to check it. Put the amp on a table and on its side with the chassis facing you. This will allow you to take out the four screws on the top of the chassis without the chassis falling. Unhook the speaker leads, tape one, and mark it so you'll remember which way they go on. Once the four screws are out, carefuly wiggle it out so you don't tear the covering.

The fuses will be located close to the power cable. Remove them and inspect them. Replace them with only same type and amperage. One of them will be a slow-blow and I'm betting that one will be the one you need to replace.