There are three versions of the C64. The C64 with a five pin connector video output (326106), The C64 with an eight pin connector video output (251138}, and the C64B which has improved system clock circuit design (251469).  Most circuit theory explanations will be the same for all three versions. Refer to schematic 326106 unless noted otherwise.

Commodore 128 & 128D Service Manual.

Commodore 64/64C Service Manual (March 1992) - PN-314001-03

Micro World MW701-A Power Supply Schematic - Had one of these aftermarket power supplies for my Commodore 64 back in the day.  They were sold by TENEX and were often advertised in Compute! and RUN magazine.