Nintendo 64 RGB

[kripp]

I'm just curious to know if the 220uF capacitors in my SNES RGB dongle are to blame for the horrible Nintendo 64 RGB results. When connected to the Nintendo 64 the image looks as if no sync line is connected, all the colors are there but the screen jumps around.

Any insight would be appreciated.

Thanks.

[Vertigo]

Capacitors would only make the image darker, not mess up your sync. I think you're missing a sync line.
Doing the 3-wire mod on its own gives you a dark, stable image. doing the quick and dirty 2-point brightening mod gives you a bright, stable image most of the time, but occasional flicker on bright whites or certain resolutions.
If you're using an RGB SCART for a US SNES, it's not meant to work on that, you're meant to use a capacitor-free cable for the modded N64.  

[kripp]

Well I've built another RGB cable for the Nintendo 64, I get the same results (unstable image, no sync) with this new cable and my SNES RGB cable. I know each cable is wired correctly, both cables work fine with the SNES.

What could be causing the sync problems? Should I use a sync signal from another point on the PCB or an IC? Using the standard composite AV cable the display looks fine, I guess the sync line on the PCB is ok then.

Any help or insight would be appreciated.

Thanks.

[viletim!]

Maybe try taking the sync from the video signal (which you've confirmed to be ok) with the aid of an LM1881...

[Dr.Wily]

You must use BF494 transistor (PnP) for image amp.

[kripp]

Dr. Wily,

Could you elaborate a bit on the use of the BF494 PnP transistor?

Thanks.

[Dr.Wily]

BF494 take input video componment (R, V and B) signal from console and amplify it. You need capacitor and resistor for amp.

You have two solutions for install this amp :

1. Directly on the motherbord, near AV\OUT, on solder side, with CMS electronic component. Wire exist, and you have just to put transistor, capacitor and resistor to thier place.

2. Directly on on the cable.  

[kripp]

Well, I'm still a bit confused.

Perhaps you (Dr. Wily) could post a picture or diagram of this amp? The way I have my cable and Nintendo 64 PCB wired, all the signals are present. The only problem is the display will not sync up.

I have tried pulling the sync signal from bottom side of the PCB aswell the IC, same results with both methods. I do have some LM1881N's on the way, perhaps this is the solution to my problem.

Thanks.

[Dr.Wily]

OK i will you prepare photo of board. But I'll try this on PAL N64, I don't know if it work on NTSC models.