Grounding Yamah consumer keyboard.

Archived from groups: rec.audio.pro (More info?)

In article <1107187590.883668.305690@z14g2000cwz.googlegroups.com>,
<inkexit@yahoo.com> wrote:
>I purchased a Yamaha PSR 290 keyboard a while back-$180. I like it.
>For the price I thought it was a bargain. The worst sounds on it sound
>no worse than the best early eighties synth strings, and the best
>voices sound good enough to use on a pro recording. Anyway, It
>generates a bit of hum. For some reason this hum is absent when I'm
>simply listening to the keyboard through headphones, but when I plug it
>back into my external soundcard (through the headphone out--the only
>out on the keyboard) the hum reapears. I'm using my computer both as
>the midi controller and the DAW--perhaps there's a feedback loop of
>some type there, or simply thourgh the AC connection, which is your
>standard cheapo radioshack 3-12 volt multi adapter with no ground prong
>on the transformer. I'm thinking about taking off the cover of the
>keyboard, finding a screw, wrapping a bit of wire around it, and
>splicing the other end into the ground lead of a three prong plug. The
>plug would otherwise be unnattached. That is, no AC current will be
>flowing throw it from the outlet.
>Is this a good way to tackle this issue? Is it safe?
>

No. Your problem is that you have too many ground lines, not too few.
Use a transformer (like a DI box or an isolation box).
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

Archived from groups: rec.audio.pro (More info?)

>>> I purchased a Yamaha PSR 290 keyboard a while back-$180. I like it.
>>> For the price I thought it was a bargain. The worst sounds on it sound
>>> no worse than the best early eighties synth strings, and the best
>>> voices sound good enough to use on a pro recording. Anyway, It
>>> generates a bit of hum. For some reason this hum is absent when I'm
>>> simply listening to the keyboard through headphones, but when I plug it
>>> back into my external soundcard (through the headphone out--the only
>>> out on the keyboard) the hum reapears. I'm using my computer both as
>>> the midi controller and the DAW--perhaps there's a feedback loop of
>>> some type there, or simply thourgh the AC connection, which is your
>>> standard cheapo radioshack 3-12 volt multi adapter with no ground prong
>>> on the transformer. I'm thinking about taking off the cover of the
>>> keyboard, finding a screw, wrapping a bit of wire around it, and
>>> splicing the other end into the ground lead of a three prong plug. The
>>> plug would otherwise be unnattached. That is, no AC current will be
>>> flowing throw it from the outlet.
>>> Is this a good way to tackle this issue? Is it safe?
>>>
>
>> No. Your problem is that you have too many ground lines, not too few.
>> Use a transformer (like a DI box or an isolation box).
>>--scott


> After the keyboard and before the soundcard? How much does one of
> those cost?
>
> How can the issue be too many ground lines if the piece of equipment
> that is producng the hum isn't grounded itself? I don't understand
> that. Could you explain?

Hi,

I just bought one of these on closeout just to muck around on but it won't be
here for a couple of days so I don't have the answer to your question. I'll be
interested in any replies in case I run into that problem. In the meantime I
wouldn't mess around trying to ground it yourself as you have described.
There should be an external solution, as the other poster mentioned but I could
use a little more explanation too.

Meanwhile you might try posting this question to rec.music.makers.synth

Cheers