Lasonic 931 hums loud when powered on

[decks&cassettes]

My lasonic 931 has a loud hum when powered on and same humm when not powered on but you hit play on the cassette
Could it be a grounding issue ? It can be heard through the music

 

[floyd]

Try pressing record and play at the same time then press stop. Repeat this step about 10 times then check it , also flip the ac/ DC switch a few times.

 

[Transistorized]

Also try with DC power versus AC power. Could be your filter capacitors drying out in the PS

 

[decks&cassettes]

Thanks guys will give both suggestions a go tomorrow