in good working condition.

From Boss:

The SD-2 features independent circuits to produce two totally different overdrive effects. In LEAD mode you get a thick, smooth sound. CRUNCH mode gives you a fat, crunchy sound that’s tailor-made for riffs and backing parts. You can even independently modify these two tones with the dual-purpose LEVEL, TONE, and DRIVE controls. What’s more, the LEAD and CRUNCH modes can be switched with the pedal switch or optional FS-5L.

Using the SD-2

• To switch between light-distortion rhythm and long-sustain solos Set the CRUNCH mode for light overdrive, and the LEAD mode for sustained distortion. Optimize the LEVEL for each and use a remote footswitch to switch between the two. (Fig 1: Level C 5, Level L 5, Tone C 5, Tone L 6, Drive C 5, Drive L 8, Mode Crunch/Lead)
• To switch between hard-distortion backing and crunchy solos For rhythm, set the LEAD channel for deep distortion and use a moderate LEVEL setting. For solos, use the CRUNCH channel for a fully distorted hard-core sound. (Fig 2: Level C 8, Level L 3, Tone C 6, Tone L 5, Drive C 9, Drive L 8, Mode Crunch/Lead)
• To switch between clean, crunch and lead For a clean sound, switch the SD-2 off using the effect on/off. With the effect on, you can use an optional footswitch such as the FS-5L to switch between CRUNCH and LEAD. This gives you instant access to three different sounds: clean, crunch and lead. (Fig 3: Level C 5, Level L 5, Tone C 5, Tone L 5, Drive C 5, Drive L 5, Mode Crunch Remote)

Specifications

• Controls: Level, Tone, Drive, 3-way Mode switch
• Connectors: Input, Remote, Output, AC Adaptor
• Current Draw: 21 mA (DC 9V)
• Recommended AC Adaptor: PSA Series