We have a Nintendo 64 and had no picture on the TV when we turned it on.
Insert AC Adaptor into the Nintendo 64 (Retro-bit.Power Super Retro 64 AC Adaptor cost $39.95 (AUD)
Insert the AV Cable into the Nintendo 64 (Tomee AV Cable - Compatible with GC/ N64/SNES) $14.95 (AUD).
We put the N64 game into the console before we turned it on.
The Nintendo 64 red light came on.
On the TV select:
Video 2/Components (This is where is says the TV choices of TV, HDMI 1, HDMI 2 etc)
Put the Red AV cable into red hole
Yellow AV cable into green hole
White AV cable into blue hole
It worked - The games are playing on the screen.
Good luck