Replacing two prong cord-polarity?

[rockon1]

Replacing a two prong non-polorized cord to a 3 prong in my Carver M1.0t power amp. Since the original didnt have polarity Im not sure which way to hook up the wires aside from the ground of course. Thoughts? Bob

[rockon1]

Ok I hooked up the hot(thin blade of plug) to the side that went directly to the fuse holder. Sound right? Bob

[Kazooman]

Here is my understanding of the proper method:

You want to connect the "hot", black (US convention) conductor to the fuse and from there to the rest of the circuitry. If the fuse blows then there will be no connection of power to the unit. If you were to fuse the white conductor the fuse could still blow, but the hot lead would still be connected to the amp. Any path between that hot conductor and ground (perhaps your fingers) would still see the line voltage. If you were to connect the black first to the power switch and then to the fuse you would still have live power on the switch poles even if the fuse blew.

You want the wire to go to the tip connection on the fuse holder, not the shell. That way if the fuse is blown and someone unscrews the fuse holder cap without pulling the cord from the wall outlet (a BAD idea) they won't get a shock if they come in contact with the shell conductor of the holder. It is actually pretty easy to touch the shell connection on some older style holders before the cap is removed.

Another tip that I have read is to be certain that the ground conductor is the longest of all the supply wires inside the amp. That way if something pulls on the cord and yanks it loose, the hot power connection will go first and the ground will remain intact. I've never seen this happen, but it does make sense.

If you are not comfortable working with line voltage and the higher voltages found inside amps you should take your amp to a service technician.