[sdiy] Powering 4ms pod

[Steve Lenham]

On 01/11/2022 15:46, Didier Leplae via Synth-diy wrote:
> Here are 4ms specs for what supplies will work:
> - 15-20vdc
> - positive Center 2.1mm barrel plug (5.5mm outer diameter)
> - minimum 20w output power
> - low-noise output
>
> I went to a local electronics store and bought a sort of universal supply. (The brand is “Classic” and model# PSE50249)
>   It has a tip which seems to fit, but says it is “5.5/2.5mm, 12mm”.
> When I plug it in to the 4ms pod, the power flashes on and off, every second or so, even with no modules or ribbon cables attached.
> Testing the supply with a voltmeter, it is indeed positive tip and around 19.5V.
>
> Does anyone have an idea what I’m doing wrong here?

Yes!

Your synth has a power socket with a 2.1mm centre pin, but your power 
supply has a plug with a 2.5mm hole in the middle. While it "seems to 
fit", it really doesn't. When you plug it in, the pin wobbles around in 
the oversized hole, only making intermittent contact. So the power cuts 
in and out all the time.

You need a 5.5/2.1mm plug on your power supply (that's 5.5mm outside 
diameter and 2.1mm inside diameter). A lot of universal supplies come 
with interchangeable plugs, but if yours does not then just chop the 
wrong one off and fit the correct one (checking the polarity when doing 
so, of course).

You are about the 10,000,000,000th person to be caught out by this (I am 
in there somewhere too).

Cheers,

Steve L.