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January 27, 2004 03:01 AM

Broken: Amp switch

Tom Smith writes:

The switch for this guitar amplifier is round the back. Seconds went by as I tried again and again to turn it off, and the little red light kept coming on again...


There's actually a good reason for there to be two "on" postitions for the switch, even if the UI could use some work. Under certain circumstances amplifiers will emit a hum with a given polarity of current. The second "on" allows you to reverse the polarity and eliminate the hum. Still, a two switch approach -- one for on/off, one for polarity -- no doubt would have been worth the extra $.25 cost to the manufacturer.

Posted by: Kent at February 4, 2004 07:16 PM

Actually this is an older amp from before we had polarized AC power cords (modern cords have a wide and a narrow blade so you can only plug them in the right way). The amp is designed to plugged in only one way and if you plug it in the other way it hums. This switch lets you swap how the line cord is plugged into the wall without having to physically unplug the cord from the wall.

Incidentally, if you get this switch set wrong and the amp malfunctions there is a good chance that you are going to be electrocuted. That's the reason why new equipment comes with polarized plugs.

The right thing to do is install a new line cord and replace the power switch with an On/Off switch.

Posted by: Phil at March 31, 2004 03:24 PM

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