Cheers, it is one of the older Boss pedals (made in Taiwan) & has ACA on the bottom.
I have been running it for a good year or more off a Godlyke Powerall on a daisychain with a cheap distortion pedal & a Moog LPF (using a polarity adaptor) & had no problems.
The "Check" light doesn't come on at all. Hmm, there's a thought, power supply??? The distortion now seems rather noisy when engaged (might be me). The Moog's running fine, but apparently it'll run off almost anything as long as you have the correct polarity & give it enough amps to draw.
I'm going for a test of PSUs.