Battery vs AC adapter in Ross Phaser: WORK DAMMIT!!!

[heyniceguy]

check this out...

so i got this old orange ross phaser. and im tired of the positive grounding bullcrap which means i have to have a whole separate adapter on my pedalboard. so i set out to mod it to a standard grounding. i install a fulltone style DC jack, rewire the in/out jacks, standard no-LED true bypass, and install a battery clip in the exact same fashion as all other pedals i've ever made. i fire it up and it doesnt work. turns out the pots have a 9V pad under them to short them to the chassis. no problem. i cut all the traces going to those potpads and run hookup wire for all the connections i cut, making sure to isolate the pot pads. so i fire it up again....

first, i tried it with a battery in the batt clip. works great. phase away.

but then i plug a boss PSA 9.6V adapter in. nothing but a little hum. i try with a ratshack 12VDC 1000ma. nothing but a tiny hum. i double checked my connections. all good. my adapters are center-negative. a-ok. so then i do this...

i plug a bare 2.5mm plug into the DC jack. i hook up gator clips from the plug to a battery. and it works superbly. but as soon as i plug in any adapter.... '''hmmmmmmmmmmmmmmmm..." and no signal or effect sound at all. so i do it again and test the voltage rails on all the chips. 9.6V across the board. tried again but this time 100uF across power rails. no help.

what the hell? why will it work with a battery plugged in the DC jack but not with an AC adapter plugged in the SAME JACK!? it defies reason!!!

[heyniceguy]

i should mention....

"positive ground" in this pedal may be misleading... it appears that the circuit is built as normal with no PNP devices, at least no PNP devices that i could identify (it's mostly 4558's). it appears that the enclosure was shorted to +9v through the input jack switching to the sleeve, output jack sleeve shorted to enclosure thus shorted to +9v.

even if there was a PNP device on this board, it theoretically would not work with either a battery connected to the DC jack or an AC adapter not work. But, reality is that battery=ok and adapter=hmmmmm.

[heyniceguy]

shameless bump... im thinking im going to have to revert this thing back.... dont wanna... dont.... wannnnaaa...

[heyniceguy]

ok since none of you greasers dared to figure this out, i had to for myself.

so i bit the bullet and reverted it back to positive ground. heres my theory....

the ac adapter and the amp were plugged into the same outlet. so the ground lug for the amp is the same as signal ground and power ground. and somehow the ac adapter created some reference to that ground and transmitted it to the pedal. so i was trying to apply my power ground to signal ground in the pedal. but for whatever reason the circuitry in teh pedal NEEDS to have signal ground be shorted to 9V power. and the battery has a floating ground from everything else, thus it didnt matter if i had power ground the same as signal ground.

golly.

[R.G.]

Sorry I missed this one earlier.

Have you traced out your grounding with an ohmmeter?

[heyniceguy]

yeah i did. all connections were there (for negative grounding). and the unit worked great with a battery, but with an ac adapter, it played hell with my signal ground and gave me that tiny buzz sound. for whatever reason, this old pedal just NEEDS to have battery power shorted to signal ground.

[R.G.]

You could do it the high tech way.

How much current does the pedal itself pull? If it's under about 10ma, and many are, you can take the 9V and ground in, leave the ground tied to the ground on the phaser, and invert 9V with a Max1044 or LT1044 and make -9V to keep the phaser happy. That way you run your pedal on 0V and -9 AND power it with 0V and +9V. For more than 10ma, you can use paralleled 1044s.

[heyniceguy]

indeed.

what ive decided to do is to use the extra outlet on my pedal baord and use a separate adapter. not the most elegant solution, but quick and effective

[RossPowerProblem]

Some unfortunate soul will stumble across this old forum desperate for help. The original adapter does not exist. Don't waste any more hours of hour valuable time, THIS WILL WORK, nothing else will. Get a Voodoo pedal power ISO5 and a standard cable pack that has a 2.1mm barrel jack on one end and the 1/8Th" mono phone jack that fits the Ross on the other. No hiss. BOOM BAM DONE.