Audio line noise from psx VIDEO...

Nazo

Nazo

2[H]4U
Joined
Apr 2, 2002
Messages
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Ok, I don't remember my playstation doing this originally, but I've had the darned thing for so many years I've already had to replace the cd spindle, the power supply, and the connectors for the controls... Curiously enough, for some odd reason I'm getting a line noise the moment I plug in the video connector, but if I unplug it the noise is gone. I tried plugging it into a VCR instead of directly into my TV, but I still get the annoying noise. I admit to not being much more than a novice when it comes to electronics (eg I know enough that I'm not scared of a few wires and resistors with a couple of volts running through, but if you asked me precicely what it is a capacitor does or how a particular chip should be wired, I couldn't really say.) Most people I know just panic at the mere thought of live wires so that if I rewire some old broken speakers or headphones, my family gets into a panic. Anyway, because of this lack of knowledge, obviously I can't just look at the PCB and figure out just how to isolate this. The only bit of information I can really give that I haven't already is that I can hook up the (well, I thought ground, but obviously not) wire that goes on the outside part of the RCA plug and get part of the video with very nearly no annoying noise, but the moment I plug in the wire that goes to the central part the noise starts. I've made an external connector (just like an extention cord and nothing more right now) which I thought to try different things with, including running it around one of those little cylindrical magnets but I just have to admit that I don't really know what I"m doing, so none of it helps. I'm hoping one of you people who do know what you are doing might just know some simple little thing that a novice like myself can do. Eg, if it involves a chip, it has to be dirt cheap (I'm broke) and something I can pick up at my local radioshack with a very simple circuitry, especially since, despite my physical science classes, I really can't remember very much about how those diagrams and all worked.

Anyway, would anyone know of a simple way to fix this? This horrible noise driving me insane. The only way I can play psx games is either get a headache and have to stop in about an hour or use emulation. And for some reason even the best emulators still are just horrible. Running too slow or with horrible video or whatever esp with 2D or hybrid games. (I'll examine this more later, but that's a seperate issue.) I think this also happened with my dreamcast but right now I'm missing the cable to find out for sure. Because of this, I think it's the TV's fault. I can't afford a new TV though.

EDIT: Ah, I just turned off my TV and it didn't stop... Howevever, I touched the audio ground to the non-central (ground?) wire on the video and it stopped instantly... I see no problems with the video, so I wonder if I should make this arrangement permanent and even rig up something to do that with on my dreamcast if it was doing it too (I prefer not to splice it's cables, but my playstation has been through so much that it's cable already was spliced.)
 
I'm afraid that I'm not very good at describing the way a sound is. I guess buzzing, but it's hard to say. The simple solution as I see it is to let you hear it for yourself. I recorded it through the line in (the noise added by the soundcard is so minimal it isn't even normally picked up by sound editors) and put it up on the space provided by an ISP. Here:
http://www.mindspring.com/~jmsloan/Line_Noise.wav
The first second or so is the line noise before I connect them, the rest is after I connect them when it gets considerably quieter (so much so that the waveform is nearly impossible to see.)

So, I guess the question is, is it harmful to anything for me to connect the audio to the video like that? It sounds like, from the site you posted, it might be that ground loop issue, but even by connecting them together like that, it might still mean that the amount of power going through could be too high or something (though I don't pretend to know just what it would take to do damage to a soundcard or tv or playstation.) Unfortunately, as useful as that information is, it contains very few actual solutions for those who aren't actually designing the equipment in the first place.
 
I'm sorry, I don't know what you mean by that. I can't plug it in any other way... And my wall sockets are horizontal not vertical. If you just mean to have the plug itself put in the other way with one pin where the other was and vice versa, then I have tried that and it made no noticable difference.

Oh, and I noticed when I looked at the spectrum used that the noise covers quite a bit more than just 60Hz (US power.) or for that matter even 50Hz. It seems the worst of it goes from the lowest I get a response from in my hardware to around 450 (and there's more past that, probably the higher frequencies being more or less responsible for the headaches.) That may or may not be proof of anything, but they did say that at least typically it was 50 or 60 Hz. I do find it interesting that I get the noise when my TV is off. It's not impossible the TV could have some running power (eg storage of information perhaps, but I believe it must have internal flash memory since it remembers things after being unplugged a very very long time) and it is Energy Star compliant for what that's worth, so I would imagine it's not supposed to have too much running through while it's off.

Oh, and I would remind you that I do believe I have switched my power supply and, I'll be honest, it was a power supply from the previous psx model. (Mine is 7501, the one I used was 7001 or whatever came before.) I wish I could remember when the line noise started, but all I know for sure is that it has been a good while but it wasn't always like that.

Anyway, I'll have to look over your link in the morning. Definitely time for a little sleep since I have to get up in roughly 5 hours (I have got to stop doing this...)

EDIT: I did skim a little. If I understand right, connecting them together would indeed eliminate the ground loop. I would still prefer a professional or at least less novice opinion on this though. It's still a bit odd though that it didn't come out as 60Hz but is a semi-complex waveform rather than a simple sine-wave, it's just very small. Interestingly enough, the other article that actually specifically says "how to get rid of them" actually still says very little about correcting such problems in more everyday situations.
 
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