AC power quality and digital pedals

[mhuss]

I was a bar gig the other night just down the road from my house, and my Strymon and Digitech processor-based pedals went completely flaky, blinking at random and not functioning at all. Disconnecting and reconnecting the power made no improvement. Surprisingly, my Line6 stuff worked fine. Fortunately the analog pedals all worked fine, maybe a little buzzier than normal. Unfortunately, I didn't get a chance to measure the line voltage, but it normally runs ~123VAC in this area even with everyone's air conditioner running. All power supplies are plugged into a surge protector, but I doubt it has RFI filtering.

Another odd factoid, there was one of those touch screen 'cash registers' happily running on the same AC circuit.

Any guesses as to what could be happening on the AC line that could cause these symptoms? Everything worked fine after I got it home.

[Enzo]

Take an outlet tester with you to the gig and check the outlets. A reversed ground and hot or something seems to me more likely that low voltage or some esoteric glitch.

Digital crap has been mainstream for 40 years anyway. Most stuff is designed to handle power line junk.

[mhuss]

I will if we ever play there it again (it was a one time fund-raiser for someone with cancer). I've played with this stuff in a lot of places, but never had a problem like this before.

The power supplies are all isolated, so as you suggest, it must be something badly wrong with the ground.

[Mark Hammer]

I loaned my Line 6 M5 and accompanying power supply to a buddy. When he returned it, the M5 wouldn't boot. It would revert to part of the setup menu, so clearly power was coming, but it wouldn't finish booting. Since the PSUshowed signs of working, and delivers 9V, I figured I'd try it out with some normal analog pedals. The "worked", but there was a high-pitched whine. I brought the M5 to a local music store and asked if they had a suitable PSU I could try it out with, since I couldn't tell if the issue was the M5 or the PSU. They powered it up fine, and I bought the PSU they were using.

When I posted this tale on another forum, it was noted that there are many ways for switching supplies to partly fail, and this may have been one of them. I don't know what my buddy did, or what he plugged it into, but I guess this sorta thing happens.

As bulky and heavy as they are, I guess there is something to be said for good old-fashioned transformers and 3-pin regulators. Maybe there's 19V coming out of the transformer, maybe there's 22. BUt as long as there's at least 17, then I know my 15V regulators are going to give me what I need.