Does anyone have a schematic on how to build a power supply for an ak20 I believe the voltages are 90, 45, 22 dc

Here's a popular kit for a battery eliminator: http://www.tubesandmore.com/products/K-101A

You need 6V for the A supply in addition to those voltages you listed: http://www.atwaterkent.info/TechData/Drawings/Images/AK04640sch.pdf