Blue Jinn
Rider of the ARPocalypse
I did the gate disconnect and socketed VCA mod to an Alesis 3630. I decided to just power it from an external PSU and removed all the power supply components and wired +/- 15VDC to a 3 conductor plug to the +15v, -15v, 0v where the regulators would have been. For some reason I thought this would be easier than locating a beefier 9v wall wart and swapping out diodes & filter capacitors (a bit less soldering). The external PSU is just a prebuilt eBay bipolar supply installed in a repurposed PC PSU box. (It does look like the reverse diode over the regulators has been cut out of the circuit though.)
I had some problem and noticed a spark between the chassis and the rack. I measured -15VDC between the chassis of the 3630 (measured from one of the top screws on the 3630 the do tie to ground on the 3630) and the rack, as well as a random AC line measured from a different power strip. Putting the PSU and the 3630 on the bench, the same, I measured -15vdc at the chassis of the power supply and at the hot and neutral of the IEC plug.
I've never seen this before, and would like some insight as to what's causing this and the best remedy. It seemed to go away if the PSU board was left not grounded to the chassis box, but any info appreciated.
I had some problem and noticed a spark between the chassis and the rack. I measured -15VDC between the chassis of the 3630 (measured from one of the top screws on the 3630 the do tie to ground on the 3630) and the rack, as well as a random AC line measured from a different power strip. Putting the PSU and the 3630 on the bench, the same, I measured -15vdc at the chassis of the power supply and at the hot and neutral of the IEC plug.
I've never seen this before, and would like some insight as to what's causing this and the best remedy. It seemed to go away if the PSU board was left not grounded to the chassis box, but any info appreciated.