This pedal was made from 1983 to 1991 and if you’re into Swedish Death Metal tones this is your ticket. The tone sweep garners a wide EQ pallet but the gain pot doesn’t do much past about 10 o’clock. The gain is also very much like a fuzz box.
I do recommend doing the cap upgrade (sold above) on the electrolytics. They tend to go bad over time which affects the circuit in a negative way. Bad caps will leak causing hum and noise and weekening the effect. A new set of caps really makes this pedal come alive.
I convert the 12 volt circuit to 9 volts which gives the circuit more headroom and bring the voltage up to more modern standards. I have also added some upper mids to the circuit and taken the buzz out of the gain and added smoothness and harmonics. I have also upgraded critical components in the circuit to give the effect a more Hi-Fi quality.
What you end up with is a very thick and almost soupy gain structure with a ton of crunch that is suitable for a wide vaviety of tones. Welcome to the your New Boss HM-2!
NOTE: I include in the instructions how to convert the HM-2 from ACA 12 Volts to PSA 9 Volts. It is an option and you can certainly choose to keep the pedal 12 volts ACA if you like.