As of this writing I have the physical adapter to connect to the unit, but not a power adapter with enough amperes to actually power the thing. The original PSU supplied 9 Volts of AC power with roughly 2-3 Amps of available power. The supply I have is delivering 9 volts of DC power which I've read it'll take just fine, presuming it has enough amperes to power everything- the actual power supply on the VIC-20 (the parts under the black metal heat sinks) are doing all the heavy lifting that later power supply bricks would be doing.
Commodore only made this variant for a little while before discontinuing it in favor of the much improved and better known VIC-20 "short boards" which are about two-thirds the size and half the weight. Rather than tear our show-ready one out of storage to show you, here's a picture I borrowed from the 8-Bit Guy.