SH-101 Mains Hum

[gowans]

I think im experiencing mains hum on my SH-101 and its pretty bad, I have a multi-voltage ac/dc adapter from maplins plugged into it, when i switch from 9v or 12v the pitch of the hum changes but is still prominent. It's actually quite loud, I couldn't use the thing in a track come to think of it. When I plug my headphones direct into the 101 i get the same problem with the hum. I know analog is gonna have a little bit of noise but this definitely doesnt seem right? Does anyone have a solution, would i need to get a boss adapter? The 101 is in mint nick too and everything works fine on it,battery compartment is clean and the faders are very good.

[steevio]

does it still hum when you have no other equipment plugged in anywhere ?

in other words just the sh101 and the headphones ?
no mixers, computers, other kit.

its probably a faulty or inappropriate adapter,
it should be 9V DC (positive sleeve / negative centre)

ive never had a hum of any kind on my SH101s
and analogue shouldn't have any noise, thats a myth.

[ekwipt]

Go and buy one of the legit roland power supplies PS-60 or something along those lines, they only have two pins (in OZ) and a filter on the lines, they're very good quality power supplies

[lem]

.... when i switch from 9v or 12v

When would this ever be a good idea? You could have totalled your 101 by doing that. Certain components are not rated for those voltages, if you blew something you could have a very expensive repair job on your hands. I definitely wouldn't recommend doing it again.

Steevio is right about the pin orientation. Not all AC adapters have a negative centre, but some have a polarity invert.

If the noise was mains related, I don't think that the hum would be voltage sensitive. It's normally the frequency of mains power itself. You could try it with batteries to confirm this....

Im guessing that you have tried moving all the controls seeing if that has an effect?
Can you mute the oscillators?
Does the noise respond to the filter cutoff?

[gowans]

the reason i switched voltage is because it says 9v - 12v on the sh-101, its fine it hasnt blew anything. im thinking this is the adapter not my 101. the hum is still there when i plug it into the mains with no other instruments or computers etc. in that socket or even that room. i'm sat in the kitchen at the mo just fiddling with it, still get the hum. whats this positive sleeze negative centre? thanks for the help btw

[gowans]

here's a sample of the sound, its that whining noise in the background. http://www.sendspace.com/file/a6qroe

[gowans]

also if the volume control of my sh-101 is on 0 and i have my headphones plugged into the 101 i still hear the noise

[gowans]

i can confirm its the lfo, when i move the lfo fader up it gets faster in its sound, but its always in the background like a little whining noise?