I have a workman ps 25 power supply. When you turn it on it remains at a constant 22 volts. the adjustment does not regulate the voltage down

SOURCE: Hifonics 1605

have you checked Radio Shack? they have a lot of cicuit board stuff for soldering

SOURCE: PS36K power supply overload problem

Most of Pyramid's supplies are based on the LM723 voltage regulator. The DATASHEET should tell you most of what you'll need to know to repair it. THIS is the schematic diagram.

If the output voltage drives the voltmeter to the end of the scale, it likely has one or more shorted power transistors.

SOURCE: ps 52 kx power supply will not hold load

thank you for your help . I have already fixed the power supply I double checked the transisters and found three bad so I replaced all the power transisters and it is fine . thanks again bob

SOURCE: Pyramid PS-21K Power Supply HELP!

check the resistors that bias the transistors, and also any zeners connected to them.

SOURCE: 20-Volt DC Power Supply instead of 12-Volt amp

Here's a few things that come to mind. An auto charging system will operate normally from about 11 Volts to about 14.5 Volts, depending on what is operating (lights, blower,etc), and whether the vehicle is at idle or not. Most car amps will operate from about 10.5 to 16.5 Volts, and outside that range, they will probably shut down.
Another consideration is your 20 volt power supply. You didn't mention if it is a DC power supply, but it needs to be. The other factor is its output, meaning its amperage rating. I'm figuring it will need to put about 5 amps, at the least, for the Sony to put out some watts. I think the line fuses of the Sony are rated @ 25 amps each.
I don't like this type of situation, because I want to say 'try it and see what happens" and I want to say 'don't do it, something may blow".
If you decide to try the 20Volt power supply, maybe if you put smaller rated fuses (say 10 amp) in the Sony amp, they will act as a fail safe. Good luck!