NESRGB Not Working Please Help!

[Landfill]

I recently installed Tim’s NESRGB board into my NES, but when it’s all hooked up via RGB or composite, all I get is a fuzzy black screen, and no audio. My NES was working properly before I attempted the mod. I don’t believe the PPU was damaged on removal. Only one pad on the mainboard was lifted when removing the PPU, but it was one of the ground pads, so that shouldn’t really be a problem. Currently I have the external voltage regulator connected, audio wired from CPU pins 1 & 2 to pads A & B, and composite video wired to pad V on the board. Jumper J5 and J8 have been shorted, and no palette selected. Also, I am using an NTSC Genesis model 1 PSU for my NTSC NES. The composite video and audio from the NES’ RF modulator doesn’t work either, but when hooked up via composite from the NESRGB board, my TV does say it’s getting a 480i signal, it’s just all black, occasionally with a few glitchy sprites on screen. Any help would be greatly appreciated.

[Sega90s]

I am no electrical expert, but I had the same exact problem when I hooked mine up at first. The issue was the ppu pin got bent to far and broke. I would use a multi meter and test continuity from the ppu pin to the socket below. If a ground trace broke I would find a way to repair it as that could be another issue.

[jwo825]

I have my selector switch wired for the center position to be OFF. The normal composite outputs will not work if the switch isn't in this OFF position. I think you have to install the switch if you want the board to function as just a pass-through.

In regards to the RGB problems, it sounds like a sync issue to me. First make sure your sync is wired correctly. Some monitors are picky on whether or not they will accept csync or sync over composite.

Lastly, which RGB cable are you using. Is it wired for the proper sync type? is it a quality cable or a cheap one?

[Landfill]

I don't have anything connected to the palette selection pins, no wires or switch. As for the RGB cable, I built a custom RS-232 to scart with 220uf caps on the color signals, 180 ohm resistor between pins 8 and 16, and nothing on the sync line because I have the board outputting 75 ohm sync. I don't believe the cable is the problem, because I am still not getting audio from the NESRGB board, or composite and audio from the RF modulator. I'm going to test continuity between the PPU and socket when I get the chance.

[mickcris]

I don't have anything connected to the palette selection pins, no wires or switch. As for the RGB cable, I built a custom RS-232 to scart with 220uf caps on the color signals, 180 ohm resistor between pins 8 and 16, and nothing on the sync line because I have the board outputting 75 ohm sync. I don't believe the cable is the problem, because I am still not getting audio from the NESRGB board, or composite and audio from the RF modulator. I'm going to test continuity between the PPU and socket when I get the chance.

did you at least short a couple pins on the palate selector? you have to have a palate selected.

https://etim.net.au/nesrgb/NESRGB-Pinout.pdf

[jwo825]

Listen to mickcris. When you installed the NES RGb board, you took the PPu out of the circuit and placed it in a new one entirely. You need to have a palette selected for it to work at all. And if you want the composite and RF to work, you will have to install the switch that enables you to select the OFF option. This basically makes the NES RGB a pass-through so your PPU is back in the original circuit.

I recommend going back to the install guide and reading over the page a couple times. It has a good overview of how it works and will help you visualize it better.

[Syntax]

You two should both go back and take a look at the switch pinout.

Off is ground floating fellas. Lol.

So not wiring a switch causes the nes RGB kit to pass thru.
If you have wired the new nes RGB composite then your old comp won't work like this.

https://etim.net.au/nesrgb/switch/

[Landfill]

If I just want to test the new composite, do I need to do anything with the palette selection pads?

Also I just read about some of the boards having fake voltage regulators (http://etim.net.au/nesrgb/background_fault/) and it looks like mine is fake. I believe I have the right cap to fix this, but i'm not sure if this is the source of my problems.

[DirkSwizzler]

Did you try popping the PPU back in the socket? and reconnecting the stock composite line to the multi-out?

My PPU died when I tried the mod on my system. All the pins and pads were physically fine. But the AV Famicom just went to a blank screen when powered on and the PPU got super hot.

My best guess is that the PPU got fried by electrostatic discharge. It was one of the first mods I'd done in over a decade and I hadn't taken any ESD precautions. I replaced the PPU and everything worked fine after that.

[Syntax]

Pretty sure the OP has a front loader as he's using a separate 5v regulator.

To kill a ppu with static you'd have to be running around the house in socks whilst doing the mod, even the you'd be hard pressed damaging it.

[DirkSwizzler]

Pretty sure the OP has a front loader as he's using a separate 5v regulator.

To kill a ppu with static you'd have to be running around the house in socks whilst doing the mod, even the you'd be hard pressed damaging it.

I had heard that's NES CPU and PPU chips were especially sensitive to ESD. Even if it wasn't ESD, something during the mod killed my PPU and it wasn't physically damaged. So replace ESD with horrifying possibility of choice.

[jwo825]

You two should both go back and take a look at the switch pinout.

Off is ground floating fellas. Lol.

So not wiring a switch causes the nes RGB kit to pass thru.
If you have wired the new nes RGB composite then your old comp won't work like this.

https://etim.net.au/nesrgb/switch/

Doh! I guess I should have taken my own advise instead of trusting my memory.

[mickcris]

You two should both go back and take a look at the switch pinout.

Off is ground floating fellas. Lol.

So not wiring a switch causes the nes RGB kit to pass thru.
If you have wired the new nes RGB composite then your old comp won't work like this.

https://etim.net.au/nesrgb/switch/

Doh! I guess I should have taken my own advise instead of trusting my memory.

I'm fairly certain what i posted was correct. all 3 floating (which is what i stated above) and all 3 grounded are both off. look at the link i posted above of the jumper settings
https://etim.net.au/nesrgb/NESRGB-Pinout.pdf


you need to select a palate to use composite video or rgb from the nesrgb. just short pad 3 to ground to select the natural palate and see if it works.

[Landfill]

I'll try it again with a palette selected.

Does anyone have, or know where I can find, a diagram showing where all the PPU pins go to on the mainboard, so I can make sure the socket is connected properly? I have a front loader by the way.

[Syntax]

You two should both go back and take a look at the switch pinout.

Off is ground floating fellas. Lol.

So not wiring a switch causes the nes RGB kit to pass thru.
If you have wired the new nes RGB composite then your old comp won't work like this.

https://etim.net.au/nesrgb/switch/

Doh! I guess I should have taken my own advise instead of trusting my memory.

I'm fairly certain what i posted was correct. all 3 floating (which is what i stated above) and all 3 grounded are both off. look at the link i posted above of the jumper settings
https://etim.net.au/nesrgb/NESRGB-Pinout.pdf


you need to select a palate to use composite video or rgb from the nesrgb. just short pad 3 to ground to select the natural palate and see if it works.

What you said was correct but it implied the problem was because OP had no palette selected.

His rf out should of worked normally with sound and picture in this configuration but it does not so something else is at fault

[mickcris]

What you said was correct but it implied the problem was because OP had no palette selected.

His rf out should of worked normally with sound and picture in this configuration but it does not so something else is at fault

You do not know that for a fact because the OP has not done anything with the palate selector to enable the NESRGB to try. It probably is something else, but this is an obvious issue that needs fixed before its ever going to work. Why not try something that takes 2 seconds that needs fixed anyways? If there is another issue that is fixed without doing this, his system is still not going to work. I don't really see the reason for you to completely dismiss this issue with his install.

Also, I would run a wire to that pin on the PPU, with the lifted pad, to where it was supposed to go. That way, that can be completely ruled out also before digging in deeper.

[Syntax]

If theres no picture or sound from the RF module with all palette inputs floating then there is no point installing a palette switch till its fixed.

No palette is defs not the issue here, and its a step which hes not really up to in the mod so there's no point focusing on it.

I'm sure many others have installed a NESRGB kit and wondered why it wasn't working before the palette switch was installed, and it is a good point, just not the issue at hand.

Moneys on the PPU install also. Good luck Landfill

[jwo825]

He did say a pad got pulled up when removing the PPU. Even if it was on the ground plane, there still needs to be a connection there when the socket is installed. I've got my money on the issue being related to that.

[Voultar]

Those palette pads are tri-state. Keeping them all floating will allow the default A/V to function, properly.

But none of this makes any difference. If he's unable to get sound out of the system, that means that the CPU and/or PPU isn't initializing properly. Turning the NESRGB OFF/ON hasn't anything to do with that particular problem.

Probably an open data line. You can afford to lose some address lines (you'll just get some glitchy graphics) but if the data bus is comrpomised, no bootz.