電源でんげん
dengen

Noun

1. source of electricity; electrical power

Noun

2. power (button on TV, etc.)

回路かいろ調しらべるまえ、電源でんげんのスイッチをりなさい。
kairō shiraberu maeni dengenno suicchio kirinasai.
You must switch off the power before checking the circuit.