Power Up Basics (VIC-20)

Once you apply power (9V or regulated 5V depending on version) and turn on the VIC-20 without anything else connected except power and AV cable, you should be presented after about 3-4 seconds, with the CBM BASIC V2 screen.

If you do not get presented with this screen, something is wrong with the computer.

For black screen (shows a valid video signal sync, but all black) it is either the 6502 CPU (UE10), Kernel (UE12), Basic ROM (UE11) or bus transceiver (UF8) or traces between them.