[sdiy] Converting rack mount to DC input?

[cheater cheater]

On Mon, Jul 13, 2026 at 10:02 PM Mike Beauchamp <list at mikebeauchamp.com> wrote:
>
> Hi Mattias,
>
> If the 16 V AC is going into a standard rectified bipolar supply, one
> side of the AC line in each of those two units is being tied to ground.
>
> In your case, I'd guess that each device ties a different side of the AC
> line to ground.
>
> Here's the schematic for a really similar power supply:
>
> https://musicfromouterspace.com/analogsynth_new/WALLWARTSUPPLY/wallwart_added_load_rs_schem.pdf
>
>
> If you modify your Y cable to swap the AC lines on one of the outputs,
> it will probably work again.
>
>
> Mike

Yep, that's exactly what I thought might have happened, too!


>
> On 2026-07-04 17:19, Mattias Rickardsson wrote:
>
> > This reminds me of a somewhat similar issue I had many years ago:
> >
> > I wanted a Korg MS-20 and a Korg KR-55 to share one external power puck.
> > (Swedish-sold old Korgs had a big external power transformer to step
> > down from 220 V AC to 16 V AC, which is then what the instrument then
> > accepts via a plug with 2 flat prongs that doesn't seem roadworthy with
> > European electrical standards.)
> >
> > So I made a short splitter Y cable on the 16 V AC side and attached both
> > instruments and turned them on. But then I connected an audio cable
> > between them (or audio cables from both units to the same mixer) and I
> > had a blown fuse! It was apparently not okay to connect those two
> > grounds together when running off the same AC supply.
> >
> > /mr
> >
> >
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