Sorry, should have said PDF alert for the link in my last post.
Actually, that’s just backwards. Regulated means the supply provides a constant voltage regardless of load (within limits), while unregulated refers to a supply whose voltage is inconstant with changing current load. And, as I said, most off-the-shelf AC adaptors don’t include any regulation, leaving that to the device being powered. Normally, a battery-operated needs not regulation, as Desmostylus says, though it may.
It’s more likely that there’s no regulator to begin with. Boss makes two different adapters. One regulated, one not. Lots of gear is designed to work with the unregulated adapters, because they have the regulators built into themselves.
In this case, it probably won’t work. Most three-terminal regulators require that the input voltage be at least 2.5 V higher than the output. So for a 9 V output with a 7809, you’d need an input of 11.5 V. Even with a 7808 giving an 8 V output, you’d need an input of 10.5 V. And unfortunately, there’s no 7807.
Thats right. Regulated means “means that the adaptor provides nearly exactly 9V whether the load draws a current as low as 30 mA or as high as 1 Amp.” I could have worded it less ambigously.
After reading a couple times, I’m not positive that you measured the voltage across after you’d turned the effect on. You did, yes, and it still was at 10v?
You aren’t lucky enough to have access to an oscilliscope, are you?
Ahhh. I see, that makes sense.
Wow, you guys have been partying without me!! This has generated much more effort that I would have expected. I thought some someone would end up telling me to switch to gold-plated directional cables 
Quoth Q.E.D.
Someone on the guitar board recommend this (same capacitance) to filter line noise. Haven’t tried it, but it didn’t sound like it would necessary just to get it to work.
Quoth Desmostylus
It is the PSA-120T. Just for completeness, I’ll give all the info on the label. Most of it is crtypic.
BOSS
AC Adapter model PSA-120T
For use with electronic musical instruments
IN: AC 120v 60Hz 9w
OUT: DC 9.6v 200mA
UL [logo] Listed 20J8
E82323
SA [logo] LR60353
SA R3W009-200 SAC
and a polarity diagram showing positive ground polarity (may not be using the right term here but the outer barrel of the plug is positive and core is negative, same as my diagram).
Quoth Bill H.
Indeed I measured the voltage with the effect turned on, input from guitar, output to amp, and playing guitar. I suppose this would have been rather comical to watch. And it measured 10v.
I do not have an oscilliscope, nor easy access to one, nor remember how to use one since the last time was when I was 18, which was longer ago than I’d care to think about.
If I had a schematic I’d gladly provide it, but it didn’t ship with one. I can recognize a resistor, a transistor, a cap, but wouldn’t know an op amp from a shop lamp.
Now it’s my turn to say that I’m stumped.
You and me both. I can only assume that either there is an open someplace or the polarity is incorrect, despite the drawing appearing to be correct.
Here’s a link to the pedal’s circuit diagram, if anyone else wants to have a go.
Looking at that schematic, I can’t see AC ripple being a problem in terms of the unit functioning. It should still work, albeit with some hum in the audio. Unless the op-amps have some sort of integral overvoltage protection (which is a remote possibilty, but highly unlikely), I can’t see 10 VDC input being a problem, either. Given your measurements, an open circuit seems unlikely as well. This is a weird one. I’d kill to actually get my hands on this thing and take some readings.
Just to be sure, I’ll double check the voltage when hooked up. It is certainly possible I reversed the leads, but I remember being very careful about that.
Q.E.D., don’t kill anyone. I’m driving to Vermont on July 18 so I’ll meet you at the Elizabeth Ikea store on the way up 
I can’t see how it can be anything but a simple problem, either an open or a reversed polarity. That’s useless advice I know, but I’m also stumped.
One of my other guesses had been that this was an ac output power supply, but since others are familiar with it and no flags were raised, that can’t be it.
As a side note: on a web search, I noticed a few people had complained that putting the battery in backwards blew the unit, so be careful.
Quoth Bill H.
Indeed. This happened to me 28 years ago in the first year I had it. I took it to a tech who cursed the lack of a schematic and charged me $12–his one-hour rate–to trace through and find out what was wrong. I’m not sure exactly what blew or how he fixed it.
But mine still works with a battery, so I haven’t blown it up yet.