Boss PSA Adapter
The PSA adapter is a regulated power supply that outputs 9V DC and can supply up to 200mA current. Regulated means that the power supply contains a circuit that helps stabilise the voltage at 9V even when the load is increasing. The earlier ACA adapters did not have this feature and when many pedals were connected, the voltage would drop.
Like the ACA adapter, the PSA adapter is available as PSA-100, PSA-120, PSA-220 and PSA-240. The number reprsents the input mains voltage it is designed for.
Powering ACA pedals with a PSA power supply