Super Famicom SCART audio passthrough

[ShutokouBattle]

I posted a thread a while ago about trying to get RGB out of my Super Famicom. Well, I got a new cable and the video works fine. Now I'm trying to get the audio working. Some background information: a couple years ago I built a SCART to 25-pin D-sub connector in order to connect my supergun to my PVM. It works pretty well.

Only problem is, I never foresaw that I might need to get audio out of the SCART connection (since my supergun only outputs sound from the amplifier), so there's no audio connector in the cable. So, I have a female to female SCART adapter. My plan was to cannibalize this adapter and connect audio cables in between the 2 female connectors, essentially creating an audio passthrough.

The problem is the sound isn't working the way I expected it to. I had the good judgement to test out the pins before I started soldering stuff to make sure they did what I thought they did. What I found didn't make sense. I didn't get any sound out of the left or right audio out pins. When I tested the right audio in pin, I got a very faint audio signal with a loud buzzing on top of it.

For one thing, why is sound coming from the audio in? I should think that "out" would mean what is coming out of the device, and "in" means what comes into the device. Secondly, why is it so faint? I couldn't hear anything over my headphones, and when I tried connecting it to my receiver, I had to turn the volume way up to hear it. The buzzing could have something to do with the fact that the left audio cable isn't connected to anything. But then why is the buzzing coming from the right speaker? What's going on here?

[ZOM]

Judging by your post I'd doublecheck if you got the pinout right(1 & 3 for audio out, 2 & 6 for in, 4 for common audio-ground) and also that everything is properly grounded.
Should be really straightforward - done it myself a couple of times while building BNC to Scart adapters.

[fagin]

Audio in is the IN of the connector going IN (i.e. the output from the console) to the SCART - the opposite of how you logically think.

The buzzing will be a grounding issue.

[antron]

"in" refers to into the TV, this is what you want because its where your console's audio out is connected. "out" is the audio output from the TV, so you can use its volume controls with an external amp, your D-sub cable probably doesn't loop this back.

it sounds like your audio ground is not connected.

fagin just beat me to it.

[ShutokouBattle]

Well, that's weird. Apparently I had the pins mixed up. Now I know the correct pins, but what happens when I test the pins doesn't make sense in light of what you guys are saying. I get a very faint signal over the "out" pins, and absolutely nothing over the "in" pins.

As far as grounding, I don't see how that could be an issue. The SCART cable goes directly to the Super Famicom, so it should be connected to ground there. Am I missing something here?

[fagin]

Well, that's weird. Apparently I had the pins mixed up. Now I know the correct pins, but what happens when I test the pins doesn't make sense in light of what you guys are saying. I get a very faint signal over the "out" pins, and absolutely nothing over the "in" pins.

As far as grounding, I don't see how that could be an issue. The SCART cable goes directly to the Super Famicom, so it should be connected to ground there. Am I missing something here?

Just to be crystal clear you should be using the following pins from the scart RGB cable to get AUDIO Breakout:

PIN 2 = AUDIO IN RIGHT
PIN 4 = AUDIO GROUND
PIN 6 = AUDIO IN LEFT (MONO)

These should ALL have wires going to them already.... I have known a number of SCARTs to not be wired correctly (either lack of wires or using the wrong pins), so if you get low sound or buzzing after following what I have said above, that could be your SCART wiring within the cable.

Each breakout phono should be as the following:

LEFT PHONO - Centre is PIN 6, Outer is PIN 4
RIGHT PHONO - Centre is PIN 2, Outer is PIN 4

[ZOM]

I encountered a bunch of male-male scart cables that had the audio pins reversed on one side of the cable, eg pin 2 on one end to pin 1 on the other, pin 6 on one end to pin 3 on the other. This is, AFAIK, incorrect and I don't know where those cables stem from. Just as a heads up.

[fagin]

I encountered a bunch of male-male scart cables that had the audio pins reversed on one side of the cable, eg pin 2 on one end to pin 1 on the other, pin 6 on one end to pin 3 on the other. This is, AFAIK, incorrect and I don't know where those cables stem from. Just as a heads up.

That's exactly the reason why you need to double check which side of the block you are breaking out from. My female to female was exactly the same! If which case you have to label up which side of the block should be plugged in for audio out correctly from the source side.

[ShutokouBattle]

So, it appears that the audio is not working properly because the SCART cable I have has no grounding for audio - at least not connected to pin 4. I don't know which pin the audio ground is connected to, or if it's connected at all. The other thing that's odd about the connections is that there are no wires connected to the grounds for R, G, and B. This doesn't make sense because my PVM is wired for Euro SCART, so if it were Japanese RGB or something I'd get a messed up signal or nothing at all. Instead the picture is perfect (albeit a little fuzzy). This is making my head hurt.

[fagin]

So, it appears that the audio is not working properly because the SCART cable I have has no grounding for audio - at least not connected to pin 4. I don't know which pin the audio ground is connected to, or if it's connected at all. The other thing that's odd about the connections is that there are no wires connected to the grounds for R, G, and B. This doesn't make sense because my PVM is wired for Euro SCART, so if it were Japanese RGB or something I'd get a messed up signal or nothing at all. Instead the picture is perfect (albeit a little fuzzy). This is making my head hurt.

You don't have to have grounds on RGB.

Let me know which pins have a wire going to them, and I can advise on which pin to use for your audio ground.

[ShutokouBattle]

Well, now my PVM seems to be dying. I guess it should have been expected, seeing as how it's approaching 30 years old.

[ShutokouBattle]

False alarm. My PVM is working fine: there must be something wrong with either the Super Famicom cable or the female to female adapter. In any case, if I can figure out which pin is the audio ground then I could make a switch to allow me to use both the Super Famicom and other systems that are wired correctly. So, the pins that have wires connected to them are: 2, 6, 8, 16, 20, 7, 11, and 15.

I think that female to female adapter was kind of a piece of crap. Besides apparently failing, the image looked kinda blurry, whereas the image from my ST-V looks crystal clear. I wonder where I could get a higher quality one.

[fagin]

I'm not sure why it would be the Female to Female "quality"... wiring yes, but I doubt the "quality" is an issue.

Take a picture of the "guts" of it and post it up.... a picture normally speaks a thousand words.

OK... on with the SNES SCART lead you have:

You have absolutely NO grounding at all on that SCART cable based on the SCART pins you state are connected.

Just to confirm.... you are on about the SNES SCART lead here, with regards to the pinouts you have provided. If that's the case toss it in the bin! According to the information you have provided you haven't even got composite video (for sync) going through that RGB SCART lead.

[ShutokouBattle]

Eh? I thought if there was no sync I would get a garbled image. The image I get is a little blurry, but it's visible.

[antron]

i've heard it's possible for some monitors to lock in on a picture without the sync. the needed data can be assumed from the color lines. never verified it personally.

[ShutokouBattle]

I just realized: there's a loose wire in here. I didn't notice it before. Sure enough, there's also a pin with some solder on it but no wire coming out of it: pin 17, composite video ground. Not sure if that really matters, but there it is.

Also, pin 20 is composite video, isn't it? So I am getting sync, it just isn't working because there's no ground - maybe? I'll play around with it some more tomorrow. I have a feeling that this wire broke off when I opened the connector, because I was getting a proper image before that and not afterwards.

By the way, do you have any theories as to why the image was a bit blurry before? It wasn't too bad, not even noticeable at a distance, but close up I could see it. As I said, my ST-V looks perfect, and the SF slightly less perfect. I noticed that it only looks blurry horizontally, not vertically. That is, each each horizontal line is clearly defined from the others, but along that line there's some blurriness.

[fagin]

I just realized: there's a loose wire in here. I didn't notice it before. Sure enough, there's also a pin with some solder on it but no wire coming out of it: pin 17, composite video ground. Not sure if that really matters, but there it is.

Also, pin 20 is composite video, isn't it? So I am getting sync, it just isn't working because there's no ground - maybe? I'll play around with it some more tomorrow. I have a feeling that this wire broke off when I opened the connector, because I was getting a proper image before that and not afterwards.

By the way, do you have any theories as to why the image was a bit blurry before? It wasn't too bad, not even noticeable at a distance, but close up I could see it. As I said, my ST-V looks perfect, and the SF slightly less perfect. I noticed that it only looks blurry horizontally, not vertically. That is, each each horizontal line is clearly defined from the others, but along that line there's some blurriness.

If the Composite Video does not have a ground I am not sure you will get a stable picture. Hence my previous comment.

Solder the loose wire back to PIN 17 and then bridge from PIN 17 to PIN 4. Give that a go. Let us know what that does to the video signal and the audio.

[ShutokouBattle]

Well I have some good news and some bad news, or some neutral news depending on how you see it. The good news is that, upon repairing the SF SCART cable, audio now works when connected to pin 17. Video also works (with audio disconnected).

Now the bad/neutral news: when I tried to connect both the audio ground and the composite video ground to pin 17, I got a buzzing noise from my speakers. The buzzing noise disappeared when the screen was black (as in, a dark section in the game) and reappeared when it was light. This could be due to the fact that my female to female adapter is falling apart after being twisted and poked and prodded for days (and also due to shitty build quality). I guess it could also be due to the video signal somehow interfering with the audio signal over pin 17. I don't really understand how that works, so at this point I'm just trying to rule out possibilities.

I decided that before I tried to do anything else I would repair the female to female adapter. At first I thought I would just reconnect the wires that had fallen off, and then I realized that the number of wires that needed to be repaired and the total number of wires that needed to be connected were the same, so I figured I might as well start from scratch and replace the shitty wires that were already there with better ones. I started on it, but it was taking forever due to me being terrible at soldering, so I gave up for the night. I think I may have fucked it up beyond repair, so I'll probably just get a new one.

Unfortunately I won't be able to work on it any more for at least a couple weeks. I was home for spring break, and now I'm going back to school. I could, of course, bring the equipment and all the tools I need with me to school, but I think they might frown on me soldering in my dorm - and it's probably a bad idea anyway.

In any case, thanks a lot to everybody for all the help. Of course most of my problems have been due to my own stupidity, but nonetheless I have gained invaluable knowledge here. Thank you. I'll be back at it again soon enough.