Keyboard malfunction riddle - I'm completely at a loss

Apr 16, 2014
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Hello, I've joined this forum because I've asked everyone I can find and can't get an answer. I'm hoping someone here has an idea otherwise I don't know what to do. My question is: why would a Korg SP100 with the same equipment work perfectly in one location and not at all in another?

I bought a second-hand Korg SP100 which I saw worked fine. I take keyboard home and with headphones in turn it on. The lights go on, there is a buzzing sound in the headphones with quickly settles to a low hum. I start to play and within a few seconds the sound cuts out. Lights stay on.

I take the keyboard for repair (the person I bought it from paid). The guy at the shop says that when he uses the keyboard, the whole thing switches off after a few seconds. He puts this down to a fault with the adapter connection and fixes a couple of bent pins in the connecting socket. The keyboard works flawlessly at the shop with my same adapter and he plays on it for two hours before having me collect it.

I take the keyboard home and plug it in. But the problem is exactly the same! I try it in all the different sockets and with each plug in the two extensions we have. It's the same problem however I try it.

I call him, I take it back to the shop. I take my headphones and my adapter and plug it in to show him that he has not fixed it. But the keyboard works fine - no buzz, no hum, no cutting out. I play it loud, soft, I play loads of notes and I am forced to admit that yes, it does work.

So I take it home and plug it, using an extension with a surge protector without other appliances attached as the guy at the shop had. It works perfectly! Then it cuts out! Then it works again. This morning it worked for a while. But sometimes when I turn it on, I can get no sound whatsoever, not even a buzzing. Sometimes it will cut out when I play more than a few notes at once (say, eight notes at once on what is supposedly a 32 polyphony keyboard) or when I play loudly but sometimes it will just cut out if I'm playing one note quietly.

It's so frustrating when I can see the keyboard work perfectly front right in front of me in one location and then not be able to use it when I get it home. Obviously the music repair shops I call don't know what the problem is and tell me to bring the keyboard in. The only thing is, they won't know whether they've fixed it until I've paid them and got it home which is no good to me! I can't sell it to someone else in good conscience.

The only other thing I can think of is that the adapter is a mismatch for the keyboard - it's 9v but needs to be 12v. But this doesn't explain why the keyboard works with a 9v adapter in one location and doesn't work with the same adapter in another. I'm waiting for a new 12v adapter to arrive but if that doesn't work I'm screwed unless I can get the person I bought it from to take it back. I'd rather fix it as it's a long way to travel back.


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