I'm posting this tutorial because my good friend satoshi matrix requested it.
First of all I take no credit for this mod I found the mod here:
I just want to make an easier to follow guide.
Okay so the idea here is to be able to get extended audio from your powerpak into the nes-101 top loader audio circuit. The pin that the powerpak outputs extended audio on is physically missing in the top loader cartridge slot. There's a couple of options to get the audio into the top loader, both require modding the powerpak. Here's the easiest option:
The nes powerpak has just 1 unused pin. Luckily the unused pin in the nes powerpak is an expansion port pin that's unused and it exists in the top loader cartridge slot. The idea is that we're just connecting the extended audio output pin to the pin that works in the top loader, we're just jumping the two pins. A few warnings before you do this mod:
1: Modding your nes powerpak will most likely void its warrenty
2: If you connect the wrong pins your powerpak won't function at all...trust me on this one.
Okay so first you open your nes powerpak...mine's already modded but here's the pcb side that we'll be jumping.
Ignore the wire...that's option 2 which I'm not going to get into. Also that connector at the top makes the powerpak no longer fit in a toaster nes.
Now for the closup of the pins you need to jump together:
Why is my soldering job so clean looking? Because I covered the pins in electrical tape and only left the parts I was soldering exposed. This will send the extended audio into the top loader pin. How you wire the audio from that pin into the nes top loader audio circuit is up to you. I never bothered wiring the extended audio into the top loader audio circuit because my top loader uses a custom audio circuit.
Hope this guide helps!