First the theory
A power supply is an electronic device that supplies electric energy to an electrical load. The primary function of a power supply is to convert one form of electrical energy to another and, as a result, power supplies are sometimes referred to aselectric power converters. Some power supplies are discrete, stand-alone devices, whereas others are built into larger devices along with their loads. Examples of the latter include power supplies found in desktop computers and consumer electronics devices.
The practical part
My, old power supply broke down and I was offered to sell my so called music box but I didnt had a casing for it so I used one from my old power supply in that case I would be without a power supply for my workshop so I made new power supply with hand regulation of voltage using a potentiometer in circuit known as voltage divider.
The potentiometer was taken from old circuit board and a transformer was taken from same board the diode brige was made on a prototype board 30x40 mm and isolated by hot glue.On the images you can see the conections and schematics for making power supply.
The price of the power supply is low, I just paid the two output female sockets.The low price is maintained using old parts such as diodes, transformers, wires, potentiometers etc.