Boss OD-2 Turbo OverDrive pedal schematic diagram

The OD-2 was manufactured as a replacement for the OD-1 in the mid-1980s and uses only discrete components. It has 3 potentiometers for level, drive, tone control and a switch for selecting two modes of operation. When set to the OFF position the sound is similar to the OD-1 but in the turbo mode it generates more gain and distortion.

Fig. 2: Boss OD-2 Turbo OverDrive circuit board - component side and foil side

• Controls: Level, Tone, Drive, 2-way Mode switch
• Connectors: Input, Output, AC Adaptor
• Input Impedance: 1Mohm
• Output Load Impedance: 10kohm or more
• Equivalent Input Noise: -118dBm or less (IHF-A, Tone center, Input Short)
• Recommended AC Adaptor: ACA Series
• Current Draw: 10mA @ 9V
• Dimensions: 70(W) x 55(H) x 125(D)mm
• Weight: 410g (14 oz.)

Transistors and diodes used in the OD-2 Turbo OverDrive:

• Q1, Q6, Q8, Q9, Q21: 2SC945-P (NPN silicon transistors)
• Q3, Q4, Q7, Q16, Q17: 2SK30A-Y (N-channel JFET transistors)
• Q5, Q10, Q11, Q13, Q14, Q18, Q19: 2SK117-GR (N-channel JFET transistors)
• Q12, Q15, Q20: 2SA970-GR (PNP silicon transistors)
• Q2: 2SC2240-GR (NPN silicon transistor)
• D1, D3-D5, D7, D9-D12: 1SS-133 (switching diodes)
• D2: S5500G (400V/1A rectifier diode)
• D6: RD6.2JB-2 (6.2V Zener diode)
• D8: MTZ6.6 (6.6V Zener diode)
• LED: LN28RP (red LED)