N64 Composite lead - Picture way too bright

Hi All

I recently bought a few N64 consoles (dont ask, I had a mad week!). I then bought a composite RCA lead off eBay to use with the Nintendos but when I use the lead, the picture is way too bright. This seems to show up on certain colours more than others (eg white). Its not the consoles or the TV (Ive tried multiple) and upon doing a search, others have had the same issue.

I found a diagram (attached) but it appears to be for an SVideo cable. From what I can gather, it seems that the cable needs to have the video grounded with a 75ohm resister but Im no expert in these things, so can anyone here let me know if that is indeed why my cable doesnt work right?

Thanks

Taj

Hello,

I'm certainly not an expert on the way that the modulation/demodulation takes place, but I can offer a little advice.

Firstly, a relevant point is that a composite cable differs from other cables, such as an S-Video cable, in that it has to carry colour and brightness signalling down the same physical cable. This in itself means that a composite signal will not be either as sharp, colourful or as "correct" a brightness as a component cable (A component cable being any cable that is designed to break up the different parts of the signal into seperate physical cables or wires).

This means that it's quite possible that what you are seeing is the result of a badly made cable that isn't able to divide it's frequencies correctly. This could be down to the type of cabling used in the make up of the cable, the length of the cable or the cable being interfered with such as a bad shielding.

The only Nintendo RCA composite leads I've ever used are the official ones, and although they ARE slightly lower quality than their equivelant RGB or S-Video leads, they are still usually well within acceptable limits, ie; not so bright that you cannot see the video output comfortably.

Since you have said that you have tried more than one console and TV, I would put my money on a dodgy cable. If it was an official Nintendo cable second hand, it might have broken shielding causing the voltage to be innaccurately sent down the wire thus throwing off the timings and causing the brightness signal to be incorrect.

Lastly relating to your diagram question:- Yes that is an S-Video diagram. As you can see it splits the Y and C signals for brightness and colour (or luminence and chroma). Because the physical cable you are trying is a composite cable, I don't believe it has the same resistance as the S-Video cable, but I'm not 100% sure on that, maybe someone else with more knowledge of video cables can advise you on that.


I don't know if this is much help to you, but seeing as the cables aren't usually that expensive, I'd probably grab another one and see if you have better luck.

Ben

Based on that diagram you are correct. Each wire is to be gounded though a 75Ohm resistor. :thumbsup:

Thanks for the info guys :thumbsup:

The cap over the connector is solid so it looks like I may have to buy another cable :blink:

Im going to try this on one my Gamecubes later on too as I read somewhere that it should work OK on them?? Ill check it anyway :)

Ive managed to get the cap cover off with minimal damage to the plastic.

As I make out from the pic attached to the first post, all I need to is solder a 75 ohm resister between video and ground right?

If thats right, can someone point me to a link on eBay to the right resisters? Ive had a look but they go on about Wattage?! :blink:

Is this the right type?
http://www.ebay.co.uk/itm/50-x-75-Oh...item43a29c899e

For anyone that is interested, I fixed this.

I got a 75 ohm resister from Maplins (for free!) and soldered it between the yellow wire and ground wire and it works perfectly! See pics attached :thumbsup:

I cant remember the wattage of the resister from Maplin's (0.3 or 0.6W I think he said??), I didnt even know that resisters have a wattage :blink: Anyway, I bought the ones on the eBay link also so Ill test them and see if they work.

Can one of the techno gurus please kindly explain whether the wattage would make a difference in regards to this AV lead? I would have thought not as I expect the current on the AV port to be very low?

BTW, this lead works on the SNES, N64 and GC :)

Easiest thing would be to find on amazon etc a 1st party Nintendo lead. never had any av problem with that, did with all the 3rd party composite and so called rub leads though.

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Originally Posted by Tajmaster

I cant remember the wattage of the resister from Maplin's (0.3 or 0.6W I think he said??), I didnt even know that resisters have a wattage :blink:

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They don't. They have a resistance.

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Originally Posted by alexh

Quote:

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Originally Posted by Tajmaster

I cant remember the wattage of the resister from Maplin's (0.3 or 0.6W I think he said??), I didnt even know that resisters have a wattage :blink:

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They don't. They have a resistance.

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I know they have a resistance, but the link on the auction above and on other resisters on eBay and Maplins all have a Wattage rating next to them as well, which is what has confused me :blink: Anyone know what that is all about?

Anyway, the cable works perfectly and I just modded another and that does too :D

Quote:

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Originally Posted by alexh

Quote:

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Originally Posted by Tajmaster

I cant remember the wattage of the resister from Maplin's (0.3 or 0.6W I think he said??), I didnt even know that resisters have a wattage :blink:

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They don't. They have a resistance.

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Well if you put a resistance into a circuit with a particular load, say 2 Ampere and the resistor can't handle it (due to materials/heat dissapation), it's gonna be ill or fry methinks... all resistors aren't created alike.

So yeah they usually have a wattage too, these things tend to matter more when making/repairing a power supply or such and not a small subcuricuit on a logic board.

Not really technically explained I know, maybe someone better w. electronics can say it better.