My DD-3 has no output from the OUTPUT jack. Light comes on, but no sound. Get sound from Direct Out.
I cracked the case open to see if any wires were loose, or PC board was smoked, but don't see anything wrong. One question though, should there only be one wire connected to the OUTPUT jack? Seemed odd but I don't see any wire that's not connected.
One wire to the output jack is fine. The "return" for that jack is through the pedal case.
What is the story behind the failure? Have you owned it for ages and it just failed? Did you buy it broken? Did you use a strange adapter and it stopped working? Please also be aware that if you power it with a "plain label" 9VDC adapter it probably wont work. It needs either a battery or the Boss PSA adapter (no substitutes).