Screen contrast issues with my N64p ..help maybe? :D

[lucidPerspective]

I've got my N64 wired up to my screen (composite). when the screen is connected to the pins in the N64 motherboard AND the N64 av cable is plugged into the AV out on the console (cable doesn't have to be connected to a TV, just be plugged into the N64), the contrast is fine.

But when only the screen is connected to the composite pin on the N64 motherboard the contrast is way up (talking major white out here, can still see kind of, but not really)

Anyone have any idea's what might be happening?

[Cojiro]

This is strange and the only thing I could think of that plugging that cable in might be doing would be tying all the grounds together on one line. Make SURE that everything is grounded correctly.

[lucidPerspective]

what do you mean by tying all the grounds together on one line? I thought ground was ground no matter where you take it from

I'm guessing that connecting the AV cable to the N64 must bridge some pins, I just don't know which ones, and can't easily tell without breaking apart my only N64 av cable

[Cojiro]

what do you mean by tying all the grounds together on one line? I thought ground was ground no matter where you take it from

I'm guessing that connecting the AV cable to the N64 must bridge some pins, I just don't know which ones, and can't easily tell without breaking apart my only N64 av cable

I know, ground is ground, what I was saying was for whatever you reason you MIGHT not have grounded them all together (video, left audio, right audio), and the cable might be bridging whatever few pins, connecting your grounds together IF they were seperate (not saying they are), so it might be worth checking that all your ground wires are grounded correctly. That is all.

[tsukasa]

what do you mean by tying all the grounds together on one line? I thought ground was ground no matter where you take it from

I'm guessing that connecting the AV cable to the N64 must bridge some pins, I just don't know which ones, and can't easily tell without breaking apart my only N64 av cable

I know, ground is ground, what I was saying was for whatever you reason you MIGHT not have grounded them all together (video, left audio, right audio), and the cable might be bridging whatever few pins, connecting your grounds together IF they were seperate (not saying they are), so it might be worth checking that all your ground wires are grounded correctly. That is all.

This.

All your grounds need to be connected together.

[lucidPerspective]

Well any other ideas then? because my ground is definitely the same ground everywhere, and I've checked all my solder connections are good. I'm pretty sure if I had messed up the grounding of things it just wouldn't work, not have funny contrast issues

Only thing to do with ground that I can think of is that I'm not grounding my screen to the N64 AV out pins. I'm taking it from elsewhere, but that shouldn't really matter, because ground is ground lol.. I don't get whats up with it

EDIT: Bacteria pointed out something..

Use a resistor to bring the signal down. Different screens can have different impedences, if the image is too bright and washed, try a 75 ohm resistor between the composite pin on the console board and your wire, that usually does the trick. If the image has correct contrast (you can adjust the resistor to a slightly different one if you need to), then between the resistor and the composite cable add a 220uf capacitor too.

Hope that helps!

Sounds good to me, I'm guessing that when the N64 AV cable was plugged in it created enough resistance to bring the signal down to a normal level