Yellow Wire is Constant on Stereo?

[Spool]

Hey Guys.

1973 Chevy C20 with a mess of wires I'm trying to clean up.

I've replaced the stereo earlier this year but it would cut out once in awhile so I decided to check the connections and follow the ground, constant and ignition.
I found it connected to (extremely messy in about 5 connections) out to the hood, and then grounded after passing a 20Amp fuse.

What I would like to do is power it straight to a On/Off switch and leave the ignition out of it.

Battery to Supply.
Radio to ACC.
Earth to Ground.

But where would the yellow constant coming off the stereo go?
And does there need to be a fuse on the constant cable?

I've uploaded this youtube clip to show the mess and fuse.
[youtube]https://youtu.be/RE-H65eWl1Y[/youtube]

Any help is appreciated. Thank you.

[ronmauer]

That looks like a mess. I would try to find the factory radio power wire near the radio. If memory is correct I think it should be a yellow wire. A test light will tell you if it has power with the ignition switch on and on accessory. The constant or memory wire I would go to the fuse box with. There should be fuses with power all the time and probably empty spade terminals in the fuse box to connect to or they make a add on terminal that connects to the glass fuse before you put it in the fuse box you can connect a spade terminal.