Reverse polarity/center positive question

[SweetFx]

I am looking for confirmation about an assumption i'm making. So I bought a holier grail reverb by EHX (the older big box one). with further research I found that it requires an 18v 500ma center POSITIVE power supply. I didn't realize this when I bought it and didn't buy a psu to match. I only have a 18v 1A center NEGATIVE psu. I was about to buy another PSU but noticed that the DC jack is wired backwards (ground and power are switched). Just out of curiosity would I be able to just switch the wires and use a center negative jack and achieve the same result?

[willienillie]

Is the DC jack isolated from the chassis?

[SweetFx]

It is on the far right of the enclosure. its hard to tell but the red wire is connected to the centerlug of the DC jack and the black wire is soldered to the top lug of the jack.

[willienillie]

Okay, yeah, just swap the wires on the jack and you'll be fine.

[SweetFx]

Thats what I figured. Thanks!! I just found it confusing as to why they configured it that way. Why use a center positive psu and then reverse the DC jack connections. Maybe an availability of psu at the time? Either way...thanks for the confirmation.

[Ice-9]

Thats what I figured. Thanks!! I just found it confusing as to why they configured it that way. Why use a center positive psu and then reverse the DC jack connections. Maybe an availability of psu at the time? Either way...thanks for the confirmation.

Probably because centre negative PSU's are far from standard in everything other than 9v DC guitar pedals. This likely came about from Boss etc using the centre negative supply as a way of allowing the input jack of the guitar to switch the battery on/off in combination with the psu jack switching. Any other power supply from electronic manufacturers is generally centre positive so finding a power supply with a centre negative other than 9v designed to power a Boss type pedal is unusual. Of course 'these days' you can find other voltage PSU's in the centre negative variety a little more common.

[antonis]

Any other power supply from electronic manufacturers is generally centre positive

So we don't have to worry about prospective shorts of male plugs hanginig around with grounded enclosures..