No sound from my n64

I have an n64 that refuses to play audio. The games play fine, but no audio. I replaced the janky av cables with fresh ones, no luck. I then bought an hdmi converter, still no luck. Today i opened it, and attempted to reheat the pins connecting the av to the motherboard using a soldering iron, but when plugged back in, the its all the same, full picture and no audio. I have been through every answer so far on this site, and cant figure it out. Is there no way to fix this thing? Is replacing the motherboard the only option? I could maybe bust out some soldering wire and attempt to add some to the connection, but i feel like I'm not getting anywhere with this. Is it the jumper pak? Is it the cartrige/cartrige reciever? Please help!