If your unit had long been sitting in hibernation, than you will need variac to power it own slowly. It's not tube unit, but nevertheless, first, I'd open the top and bottom covers, sweep it with clean paintbrush and/or vacuum, spray the whole thing especially rotary switches, all pots and knobs with DeOxit D5 (you may add F5 formula on mechanic components such as rotors of tuner and rotary switches ball bearings), than connect unit via variac and step-by-step increase voltage every 10...15 min to operating voltage. I usually do that within 3...4 steps i.e. within an hour towards the operating outlet voltage. Than I keep it running for an hour. SX-1280 has stand-by load resistors so running it unloaded isn't an issue -- just make sure that receiver is ON, but all speakers are OFF.