Great, so a few weeks back I became the proud owner of the mid-80′s premiere games console, the NES. This would be the second time one has come into my possession, although the last one was sold in 1994 due to my then current obsession with a new 486 PC that had a little game called X-Wing. The ‘new’ console also came with a MIDInes cart, which does what it says really, it plays the NES sound chip via MIDI. I’ve been digging it a lot however there was one major drawback.
Having the NES hooked up through its standard audio socket and into my mixer had a dreadful buzz/hum. This would be slightly resolved if you set the MIDInes cart to the no-video out put mode but it wasn’t enough. A bit of Googling around the net and a few forums later I discovered that really the hum was unavoidable, due to the way the audio came out out of the system. That is unless..
You can tap audio directly from the NES sound chip, which avoids all of those noise inducing components and parts and gives you a 2 channel split of audio coming out of your machine. Now, I found this out by using the following sources, I in no way came up with this idea and sure as hell don’t take any credit for it:
All credit goes to these people/links:
Due to the fairly un-static nature of the internet and the lack of a really clear guide I felt compelled to be writing this post/guide/thing.
GUIDE CONTINUES BELOW!
Disclaimer: I’m not much of an electrician and I’m putting this together for reference purposes only. If you decided to follow what I do here and blow up your console/house/street then that is your problem, although don’t be too discouraged as the reason I’m writing this is partly to record the process of how you would go about doing this modification and why, plus I found it pretty easy, meaning in the scheme of things it must be really easy.
Right, enough babble etc. Let’s go. Again this is written as an idiots guide, don’t get all bent out of shape if I’m stating obvious facts.
Things you need:
- cross-head (phillips) screw driver
- 2x RCA jacks
- 2x 1uf Electrolyte Capacitors
- Single Core shielded wire
- Drill (or anything else you can use to make holes in your NES)
- pilers and wire strippers
- Soldering Iron
A Maplins raid..
Step 1: Open your NES
Depending on the model this maybe very easy, or hard. I found it easy, I have a standard PAL nes. This was a time before Nintendo used thier own tri-angle screws, and you just need a standard phillips-head screw driver. Some of the newer models may use the awkward Nintendo screws.. Anyway, once you take all the screws out of the bottom of the unit the top half pops off revealing the NES insides.
From here work your way around the circuit board removing all the screws that hold the board in place on the case. You can remove the top metal shield as well at the same time. (one nice thing about the NES is all the screws are the same, bonus, keep em safe though)
Step 2: Get the board outta there
Disconnect the controller ports and power switches from the circuit board. They are quite stiff but can be safely pulled out of the sockets. Once you have pulled them out you can lift the whole board out of the case and remove the metal case from underneath.
Step 3: Find the chip and the audio pins.
Find the RP2A07A chip! (In a NTSC NES this will be 2A03) Flip over the board to reveal its juicy innards and the chip will be easy to spot. Prepare your wires, I used 2 roughly 20cm lengths and stripped it back to reveal about 5mm of the core. Don’t do what I did here and forget to strip the other ends as well, its much easier to do now than once the wires are soldered on.
This is the chip!
So time to figure out where you are going to solder that wire. Luckily this is pretty easy to identify. The two audio pins have resistors coming off both of them and they are the in the bottom left of the chip. Pictures help:
The resistors make attaching the wires a bit simpler too. I wrapped the stripped wire around the positive leg of each resistor and used only a small amount of extra solder to attach the wire. Don’t attach the wires directly to the chips pins, the heat may do serious damage to the chip. Once the two wires are in place relax, that was the hardest part!
Step 4: Drill the holes, sort the audio jacks out.
Okay, next up is sorting out the audio connectors. As I said, I used RCA jacks, I used gold plated ones too because I’m extravagant, and at a couple of quid a pop from Maplins it wasn’t that much of a stretch. You can also use ordinary 1/4″ or 1/8″ jacks, but these do go quite far into the case which might cause some issues.
I drilled the holes in the back of the NES with a standard drill I have lying around. The plastic is pretty easy to get through.
Next is an important bit, push the jacks through the holes and get the soldering iron ready again. I soldered a capacitor to the end of each jack. Now don’t do what I have done in the pictures, which is get them the wrong way round. Ignore this mistake! Solder the POSITIVE (ie. not the leg marked with the white stripe) to the RCA jack.
Remember! These capacitors are the WRONG WAY ROUND.. the Positive legs are the ones that are supposed to be attached to the RCA jacks.
Step 5: Grounding
To ground the circuit I ran a wire from the ground pins on each RCA jack and considered soldering it to the ground pin of the circuit. However I was then informed a far better thing to do would be to just attach the ground to one of the screws holding the board in place. Get the wires ready for now and pop the nuts over the RCA jacks to hold them in place.
The finished jacks with grey ground wire coming off.
Step 6: More soldering
Now solder each of the wires coming off the circuit board to its respective leg of the capacitors coming off the RCA jacks. The capacitors stop shorts coming into the NES and messing everything up. You can see from my photos my method leaves a fair bit of exposed metal. I actually re-opened my case after I finished and used some electrical tape to wrap up all the connections to keep them separate.
Step 7: Testing
A really good idea before putting everything back together is to test everything. I placed the board back into the case and connected up only the large blue power socket. I also screwed in the ground wire.
The audio ground wire is tucked under the screw circled in red.
You should be able to load a cartridge and plug in the audio jacks and power now to see if everything is working. From one jack you should hear the two pulse channels and from the other jack should give you the triangle, noise and sample channels. If both signals are coming from each jack then you have either a grounding issue or your capacitors are in the wrong way. check all of your connections then try again.
Step 8: Re-Assemble
That is pretty much it! Remember to plug your controller ports back in and the metal casing around the board. Watch out for catching your audio wires on the metal cases, it is quite sharp on the edges and can slice through wires if you don’t watch out. Like I said earlier, to prevent the exposed wire touching bits it shouldn’t have I used electrical tape, you could also use hot glue or something. Get that case back on and you should notice you NES now quietly sings without the hum.
All done and sealed!
In the other articles I linked at the start, some people have tapped the audio line and used a potentiometer to act as a mixer between the ‘stereo’ and mono signals. If you use your NES for gaming I recommend this, but as I’m using mine for music, with an external mixer I felt it would be an unnecessary hassle. Also the old jack on the side still works too for when I want to bust out Mario 3.
And thats it. I hope this has helped