ideas on what might be causing the receiver chasis's to be "hot"
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The AC line input to the power supply has capacitors bypassing both
sides of the line to the chassis. That puts the chassis 60 VAC (one
half of the 120 VAC line voltage) above ground regardless which way it
is plugged in. Best idea is to install a 3-wire line cord and connect
the safety wire (the green one) to the chassis. You can also use a
polarized plug and bypass the neutral side of the line to the chassis
and the hot side of the line to the neutral. The 3-wire cord is the
best idea. --Ed