Accuphase E-280 Voltage Conversion (100V to 120V)

Since you have a step-down transformer, you can confirm its transformer taps by power up the E-280 at 100VAC, using a DMM set to AC voltmeter, measure the voltage between yellow - orange, and between yellow - black, you should get both reading of 120VAC.

Swap the two wires:

RED <---> ORANGE

BLACK <---> VIOLET

That will convert the E-280 from 100V to 120V.

I suppose the last picture above is the post-modification (working at 120v) ?

@jcgoobee

Yes, if your E-280 has the same connections and color coded wires.

120V connection:

100V connection: