alright braintrust, here's a fun one. I was sent a vintage Rosac to check out/repair/mod so that it is no longer powered by 2 separate 9v batteries. It works fine on a battery, he said, but a voodoo lab power supply to battery snap adapter made terrible noise.
those were my findings exactly. battery sounds great, clipping a 9v power supply makes the most obnoxious buzz. here's where it gets weirder. if i clip the negative to either the chassis or one of the bare bus wire grounds, it's totally fine. but in either position for the "battery on/off" switch (which has good continuity) it makes awful noise. there are also 16uf electrolytic caps on the footswitches, which is something i've never seen before.
if anyone is clutching their pearls, rest easy. my plan was to use the hole for the battery switch to hold a dc jack, and every change i make be 100% reversable. trouble is i'm not 100% sure how to approach it if i can't just connect (-) to (-) and (+) to (+). definitely some really interesting vintage wiring tactics going on here that are beyond my understanding at the moment.
thoughts?
those were my findings exactly. battery sounds great, clipping a 9v power supply makes the most obnoxious buzz. here's where it gets weirder. if i clip the negative to either the chassis or one of the bare bus wire grounds, it's totally fine. but in either position for the "battery on/off" switch (which has good continuity) it makes awful noise. there are also 16uf electrolytic caps on the footswitches, which is something i've never seen before.
if anyone is clutching their pearls, rest easy. my plan was to use the hole for the battery switch to hold a dc jack, and every change i make be 100% reversable. trouble is i'm not 100% sure how to approach it if i can't just connect (-) to (-) and (+) to (+). definitely some really interesting vintage wiring tactics going on here that are beyond my understanding at the moment.
thoughts?
