Intermittent crackling/distortion sound

Hi all…just got a used pre-built shruthi, which i love. The thing is – it makes this strange crackling/distortion sound, which appears every 5-10 minutes. It kind of builds up in volume (in time to the notes) over a second or so, then disappears. Any ideas as to what it might be? Thx…

What type of power adapter are you using?

It should be a center pin positive, 9 volt AC/DC adapter that can deliver 300 milliamps or more.

Hey audiohoarder…
yep: 9V, 305mA

I fear this not sufficient enough, as it is not wise to drive a power supply over 80% of their max currency. So if 300 mA are requested the power supply should deliver at least 375 mA. And even then the topics ripple and efficiency aren’t really covered…
So i personally would go for a way beefier power supply.

Thx nightworxx…will give it a go and see if it helps.