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It's been a while since I've played my NES but last night while playing some Castlevania I noticed an irritating buzzing sound from the speakers. It's very noticeable on the title screen. But it goes away, or at least isn't noticeable, once you start playing. Decided to try Bubble Bobble, and the same thing. I know it's not a Sega consoles but considering the collective audio knowledge on these forums I thought this is where I'd get the best advice.
Any advice to get rid of it?
Never owned one, but I think I can think of few things.Quote:
Originally Posted by Polygon
Cables plugged in correctly and no shorts in them?
Does it show up on bright screens more? Video line noise.
Audio has changed or degraded? Sign of bad caps.
Ground loop? These can be tricky to rule out. Generally a line buzzing sound heard when things are quiet as the impedance differences between two different devices will start resonating on the building's power line frequency (60 Hz with harmonics at 120 Hz and 240 Hz and so on for example). Things can happen to picture as well.
Faulty power supply not outputting what it needs?
Bad motherboard revision?
The NES isn't exactly known for greatest sound either. I've heard people say things about it before.
If you're using an RF unit type connection, did the MTS Stereo decoder get tripped on your TV (actually had a TV that did this, it buzzed a little more than normal when it got tripped, detecting a pilot tone that was not present and the source that's transmitted or a signal in mono might cause in an MTS decoder to react, because it runs on the same frequency as the horizontal scan rate for stability, it's one of the reasons mono mode on those type of TVs is offered, happens more on some than others, probably due to faulty tuner circuit or noise from inside the television blending in to something else, it can also affect other devices that have built-in MTS decoders, too). Assuming you live in the USA or Canada. The signal is still always mono regardless of the TV or device says it is.
Not a problem I remember experiencing with the NES.
On top of what Chibisteven listed, this can sometimes be a symptom of cheap, non shielded RCA cables, if you are using RCA and not an original RF cable.
Haha, eww. No R/F here. :)
I'm actually using the factory A/V cables. I have about 10,000 sets sitting around I can swap out with. You guys have given me a lot of things to check out. Caps all looked fine when I last had it open a few months ago. Too bad caps a tricky and don't need to burst to be bad. :/
I'll try some of those ideas out and post back. Thanks guys.
So you have access to 10,000 different sets of AV cables, but do you have access to a spare NES? Could be good to compare with a different one.
Yeah, I was exaggerating slightly. We'll just say there are a lot around here. I also have about 4 other NESs as well. Honestly, I should have tried the cable first. I just got home from work and tried another cable and it sounds perfect. Well, as perfect as a toaster NES can sound.Quote:
Originally Posted by MaxWar
An NES naturally has a bit of video noise in the audio output which I believe is due to the lack of any sort of pull-down resistor on the extra audio input from the expansion slot. Locate resistor R9, a 20Kohm resistor, and stick a 2.7Kohm resistor to Ground where the audio signal from something connected to the expansion slot comes in (one side of the resistor is linked to the 12Kohm and 20Kohm resistors from the 2A03 - you don't want to solder the 2.7Kohm resistor there).
I had to deal with this issue on my Top-Loader NES trying to adapt the original 1983 Famicom audio amp to the console. If it was just the 2A03's audio going through, the noise was so faint, it was barely audible, but as soon as expansion audio (from pin 51 of the cartridge slot as that's where it passes on my PowerPak and Famicom to NES converter for this console) would be wired in, the audio became really noisy, noisier than a stock Front-Loader NES. Putting a 2.7Kohm resistor to Ground before expansion audio gets mixed in (via 68Kohm resistor in this case instead of a 20Kohm resistor as the audio is too loud like this) fixed the noise.
In this video you can hear that buzzing sound on this guy's NES too:
https://www.youtube.com/watch?v=Pj0ofU0CBjE
RF box capatiors? Bad transformer?
I'm interested in how you fixed the noise, as I also have this problem on my top loader. Could you explain in alittle more detail were you installed the resistor.Quote:
Originally Posted by Ace
The resistor is necessary if you're adding in expansion audio from pin 54 or 51 of the cartridge slot (the Front-Loader NES should have had this in the first place to prevent extra noise from getting into the audio signal). You must install a 2.7Kohm pull-down resistor between the expansion audio input and Ground, then take a 68Kohm resistor (on a Front-Loader NES, there is a 20Kohm resistor at solder spot R9 which is where this 68Kohm resistor should go), wire your expansion audio input through that resistor, then solder the resistor to the negative pole of the 1uF capacitor in the audio amp. This is where the 2A03's audio gets mixed in and is where expansion audio should be mixed in on an NES as the Famicom's passing of audio through the cartridge doesn't work on an NES.
Ok since I'm not adding in expansion audio maybe this inst my problem? My buzzing sound gets worse depending on how bright the graphics are. I'm thinking interference. My front loader does it too with a different cable\psu\tv. maybe this is normal. the top loader is av modded I would blame that but the front loader is exactly the same. It really isn't that bad just noticeableQuote:
Originally Posted by Ace
The Top-Loader NES has no audio amp, so you need to add one in and bypass the passive audio circuit on the motherboard. With this, no matter whether expansion audio is wired as I mentioned or not, you will get very clean audio with minimal noise.
Regarding the Front-Loader NES, even without wiring expansion audio, you will still get noise as Nintendo wired up an audio input from the expansion port to the audio amp through resistor R9, which is actually a floating input as there's absolutely nothing going through this part of the audio amp. You should still solder a 2.7Kohm pull-down resistor from the audio input on the expansion port side of the resistor.