Try putting a decoupling capacitor on there. 0.1uF should be enough. Your SCART cable also may not be wired correctly and using composite video might not be a good idea.
The "scart" cable is actually just a DB9 to DB9 straight through cable. I had previously modified the scart to ypbpr adapter to have two DB9 inputs, selected by a switch That's all functional on my Mega Drive (the connectors are all wired the same as the Commodore 1084s monitor, as I also have one of those, and it means I can connect my gaming consoles to this monitor, or connect the Amiga to the scart to ypbpr adapter using the standard amiga-1084s cable) I'll try adding a capacitor today, and change the sync signal, although the scart-ypbpr adapter, and tv, have no issues using the composite video signal as the sync with the Mega Drive.
I added a 0.1uF ceramic capacitor, but when I came to move the sync signal, I realised this board has no components connecting that pin on the rear connector, to the rest of the board... Is this common?
If the board is a NUS-CPU4 model like 2 consoles I have then the sync signal traces are there but have no components on it. NUS-CPU 3 and earlier do have sync on the plug. Just get a sync stripper. It will strip the video from the composite line leaving a pure composite sync signal. LM1881 is the part number for what you need.
What kind of cable you using?. Are you using a Raw Sync Cable (Takes Sync from Pin 3 from the multi-out) or a regular RGB scart cable? If your using a Raw Sync cable, you'll have to link pin 7 (Luma) to Pin 3 on the multi-out because composite sync is not connected to the multi-out on the CPU-04. If your using a regular RGB scart cable, you should be getting a picture on screen. Though it should work with composite video as sync but its known to cause some artifacts. It's best to lift the composite video pin on the ENC-NUS chip and link 7 to 9 or cut the Composite video trace and link 7 and 9 on the multi-out if your using a regular RGB scart cable . I believe sync is the issue on why your not getting a picture. it was confirmed a while back that the LM1881 does not work or does not work well with the N64 by a very experience member on the boards here (APE?) *Oops... should of read the thread*
*Edit* i dont what to say for this one. All i can say is try feeding a different type of sync to the ypbpr (component) adapter. Try luma (Pin 7) first and if that doesnt work, try tapping composite sync from the VDC-NUS chip.
No, I'm using the composite video. This console doesn't have the buffering circuit for the composite sync. But it displays nothing, so I don't think its a sync issue...
I might try feeding the RGB signal directly into a monitor, without the amplifier/buffer circuit. I know it will give a dark image, and can possibly damage the N64, but at least it will tell me if I even have RGB at all!
Anyone have any ideas about this? Or should I just put the console back together, not working still... Thanks!
So with composite video as sync you do get a raster, but a blank one? Are you sure you have chosen suitable wiring points? If you do end up needing composite sync, there is absolutely no reason to use a LM1881. The N64's DAC directly provides a digital composite sync signal. To use it properly you'd need to build a sync driver, or just try a 680 ohm resistor, which will work but the signal will have poor rise and fall times. Technically LM1881 require a buffer-driver circuit as well, but many people naively opt to directly wire the digital C-sync output to the display's analog input.
