Also, can I just run all the ground wires to various screws using electrical tape or glue?

snd1&2 dood. just look for the 2a03.

I've done it to a top loader. The mod is exactly the same.

Er, yes - but where are the audio outputs on the board?

Hey, does anybody know of any documentation on doing NES audio mods that covers the top-loading model 101? Has anyone done it? I know I've seen it done quite nicely (Crashfaster uses one, for ex.). While I could probably figure it out, it would be great to see a decent shot of the board with the audio out points marked, for example. All I've found so far is "A/V mod" discussions on benheck style sites that pretty much gloss over the issue of audio. The 101 is hard enough to find at a decent price that I'd rather not dig into the thing without some idea of where I'm going first if possible.

I've done it to a top loader. The mod is exactly the same.

Only thing I may need to work on is changing the resistor value for the cartridge input as it sounds a tad distorted when played through my mixer. I think that's always been an issue. Recording the output directly doesn't seem to be a problem, however (though that could be because I often only record one channel at a time and the distortion is mostly when playing the saw and square channels at the same time).

I also now need some double-sided tape to adhere it to the bottom of the NES case since it's small enough now that it can move around a bit.

So I guess some small todo's but the main concept appears to work. Next up, is trying Theta_Frost's suggestion of having a passive mix out

Pics

For my newest design, I had the board fabbed with DorkBot and moved most components to SMD. Here is a quick pick of it I threw up on my band's Facebook page.

Dorkbot does boards in groups of 3 so assuming I don't mess up too many times, I should have a spare or two. If you want it, you're welcome to one. Just pay shipping if you don't mind, assuming it's over a few bucks (such as if I need to ship international or something). I'll be out of town next week and I'd rather make sure the design works before giving it out so it may be a little while before I'll be able to ship it out, but otherwise let me know if you'd like one!

As far as the passive mixer, that would have been a really good idea! I think Kitsch mentioned that to me a while ago but for this round I was concentrated on saving space over adding features. A passive mixer wouldn't be very tricky, and in fact would be a pretty good use of the op-amp (to help boost the attenuated signals from the passive mix).  I've added a note on my schematic to add that for the next revision, depending on how this new design works out.

P.S. Kitsch and I have been passing ideas back and forth about this design so he may or may not be working on one of his own, which will probably be pretty awesome so if you're not in any hurry, you might want to see what he comes up with!

For what it's worth, I went with an op-amp style (Cmoy-inspired) solution. First attempt was using a home-made board but I have now made an SMD version that is a good deal smaller. I like using an op-amp because it would sacrifice itself before you end up doing any damage to your CPU itself (say due to static from plugging in an audio jack or something).

The downside is that it needs power. My first design required a separate power brick but I found a low voltage op-amp from Texas Instruments (Burr-Brown) that can be fed with low enough voltage that I can just use one power brick into the NES and tap off those inputs. That requires using a DC power brick though (the original NES power brick is AC), but a nice clean linear regulated power brick should work just fine, if not better, than the original power brick anyway.

You can see my first attempt here:

http://www.moocowproductions.org/nesa/

Still waiting on parts for my new board so I can't claim success for it just yet.

If you etch an extra of that new board I would buy it from you in a heartbeat!  Also, it might be nice to take advantage of that 4th RCA jack and sum the 3 channels into an extra mono channel.  Great job though man! 

The downside is that it needs power. My first design required a separate power brick but I found a low voltage op-amp from Texas Instruments (Burr-Brown) that can be fed with low enough voltage that I can just use one power brick into the NES and tap off those inputs. That requires using a DC power brick though (the original NES power brick is AC), but a nice clean linear regulated power brick should work just fine, if not better, than the original power brick anyway.

You can see my first attempt here:

http://www.moocowproductions.org/nesa/

Still waiting on parts for my new board so I can't claim success for it just yet.