I am the original owner but no longer have the box. The manual can be found online here:cdn.roland.com/assets/media/pdf/PSM-5_OM.pdf

The pedal is 100% operational and is in excellent condition, given it is 30+ years old. The pedal comes with the original AC adapter and a parallel DC daisy-chain cord (designed to power up to 7 units).

The PSM‑5 was the first BOSS power supply in their typical compact pedal format. Not only can it provide 9V power to up to seven BOSS (or compatible) 9V pedals but also it acts as an effect loop switch. When the loop is switched off, the signal is passed direct from the input to output jacks. When the loop is switched on, the signal is passed from the input to the Send output which can be connected to any number of effects before being routed back to the Return socket and then to the (Amp) output. 

Features:

• Made in Japan by Roland Corporation in 1986
• BOSS treadle footswitch turns the effect loop Send/Return on and off
• LED ‘Check’ light to indicate when the effect loop is in use (red for on and green for off)
• ¼” input (Guitar) and output (Amp) mono jack sockets plus ¼” effect loop Send and Return mono jack sockets
• External 9V DC power supply input  (no internal battery facility)
• 9V power supply out for up to 7 other BOSS pedals (PSA powered)
• Red ‘Made In Japan’ label on the base of the pedal