NESRGB? Garbled title screens/other graphical errors in some games.

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Coughdrop
Posts: 6
Joined: Thu Dec 01, 2022 11:57 am

NESRGB? Garbled title screens/other graphical errors in some games.

Post by Coughdrop »

Hello!!

I just got an NESRGB V4 installed into my PAL to NTSC converted front loader console and after already much troubleshooting it's working... Kind of

With a good amount of games, nothing is wrong, they look and sound perfect.
(Mega Man 2, 3. Shadowgate, Double Dragon, TMNT, Kirby's Adventure, Contra, Dig Dug 2, Pac-Man, Urban Champion, Excitebike)

But some other games have garbled aspects, mostly just in title screens oddly, when you hit Start these games look and play like they're supposed to.
-Super Mario bros, Ice Climber - Garbled Title screen)
- Lum No wedding bell - Garbled title screen, Music and game is tinted blue)
- Donkey Kong Classics Garbled title screen, DK plays and looks fine, DK Jr, is completely corrupted graphically.)
- Super Mario Bros 3 works like it's supposed to but consistently shows white sprites behind the Lives display on the world map after it dissapears.
- Hello Kitty world does not work 99,9% of the time, when i did get it to boot it worked for about 6 seconds before it corrupted and stopped.

(Some side notes)
-These games were working before with the same parts with a Socketed PPU
-The NESRGB has been installed with seperate 7805 to split the load and 7805 in console has been replaced As console was getting super hot and overheating before.
-Oddly at first the game not wanting to work 99% of the time was Mega Man 3, but after these issues cropped up it's one of the games that works without fail every time, when before i had to reset the console and power cycle til it started to work.
-I had way more graphical problems after my NESRGB install, but installing a 100Pf Ceramic Cap between PPU pins 13 and 20 solved some of the issued i had with the background corrupting, have tried other Ceramic caps but this seems to be the sweet spot.
-All games are known working and Cleaned
-Am using a DC 9V 2A power supply, same things happen with the official Nintendo AC power supply.
-Have another issue with this NES and NESRGB where the console only powers on with the NESRGB's Reset combo held, Don't know if this is related. I disconnected the reset line from the NESRGB for now so it stays on.
-These garbled Graphics also happen over the composite output with the NESRGB turned off.
-The Pallete switching with the controller is working like it's supposed to.
- Super Mario bros does the same thing with the Famicom version, PAL NES version, and Bootleg Multcart, however Mario Bros Duck Hunt skips the game selection and jumps straight into Mario bros with the corrupted title screen

Does anyone know if this points to something in particular being bad? I've tried 3 Pin connectors and all give the exact same problems and symptoms differ without touching the cartridges at all. These pin connectors also work fine in other consoles and have worked fine in this one before. Leading me to believe it's not that.
Different carts still give the same problem with the aforementioned games, even multicarts give me identical problems with Mario Bros and Ice Climber. I'm almost thinking it's RAM related as it's consistently glitchy with large graphics on startup, and on the occasion Super Mario Bros does look like it's supposed to hitting reset once messes up the logo again.

Some composite captures with the NESRGB turned off.

Image

Thanks to anyone reading all this and for any replies, it's very much appreciated.
Lelynx08
Posts: 3
Joined: Tue Apr 25, 2023 2:54 pm

Re: NESRGB? Garbled title screens/other graphical errors in some games.

Post by Lelynx08 »

Hello,
I installed a nesrgb v2 years ago.. not working well, and today came back in!

I fixed couple of things on the famicom av board and on the nesrgb board.. basically some tracks cuts..
To come up to exactly the same problem as you! Scrambled title screens on some games, not all. But also some games not starting at all on the everdrive with a grey screen at launch.
Like : castlevania 2, chip n dale, Mario 2,3, and many others not starting.
I have not this issue with famicom games, just title screens or minor bugs.. but games playable almost perfectly!!

• when removing the nesrgb, the famicom works perfectly with all games! No glitch, no problem with everdrive, everything is working ! So, the problem is clearly on the nesrgb board.
• I checked continuity from the famicom Board till the end points on the nesrgb, all are bipping like schéma on etim.
• I see 5v on the nesrgb board and on the ppu.
• I doubt its an issue on ram, ppu or cpu because it works without the mod.
• the graphic problems are the same everytime, exactly. If I launch from everdrive, pal or jap version.

https://ibb.co/QjHhrfm

Did you find anything?
Somebody else could guide me to check something specific?..

Thanks!!
Lelynx08
Posts: 3
Joined: Tue Apr 25, 2023 2:54 pm

Re: NESRGB? Garbled title screens/other graphical errors in some games.

Post by Lelynx08 »

Hey All,

Try to continue my investigation..
- I rechecked everything from the main board to the ram, cpu. Also from the ppu on the nesRGB board to the main board and to the first point of the nesRGB next component. - Everything seems to be ok.
- I changed the PPU, stil the same problem. So I can exclude PPU for sure.
- Tried another PSU and another RGB cable.
- Without the mod, the image is without artifact.
- The fact that some games are not starting from everdrive, but well from the original cartridge makes me think that something linked to CPU is not starting..
- on 90% on my original games, I have no problem!
- SMB title screen corrupted - game running too fast
- Double dragon 2 - screen black, grey, red, blue.. changing like that.
- Ice climber title screen corrupted
- Time lord , the game is blinking when playing
- Turtles mutant, I have the impression the game is not smooth..

From what I discovered/ question about :
- SMB having to read CHR-ROM to display the title screen properly. Do you know what can I check to verify this is well working from the NesRGB board?
- The EXT 0..3 are all connected together? Correct? so bridged?
- I have the impression it's an issue at the altera chip during the decoder palette rom process.. maybe faulty?.. :p Basic checks on that to advice?
- Problem of saccade or everdrive game not starting would be more related to cpu no?

I join additional pictures to see the problems I have.

https://ibb.co/4JK93zL
https://ibb.co/d0J0MqC

Thanks in advance for the help.
Lelynx08 wrote: Tue Apr 25, 2023 3:13 pm Hello,
I installed a nesrgb v2 years ago.. not working well, and today came back in!

I fixed couple of things on the famicom av board and on the nesrgb board.. basically some tracks cuts..
To come up to exactly the same problem as you! Scrambled title screens on some games, not all. But also some games not starting at all on the everdrive with a grey screen at launch.
Like : castlevania 2, chip n dale, Mario 2,3, and many others not starting.
I have not this issue with famicom games, just title screens or minor bugs.. but games playable almost perfectly!!

• when removing the nesrgb, the famicom works perfectly with all games! No glitch, no problem with everdrive, everything is working ! So, the problem is clearly on the nesrgb board.
• I checked continuity from the famicom Board till the end points on the nesrgb, all are bipping like schéma on etim.
• I see 5v on the nesrgb board and on the ppu.
• I doubt its an issue on ram, ppu or cpu because it works without the mod.
• the graphic problems are the same everytime, exactly. If I launch from everdrive, pal or jap version.

https://ibb.co/QjHhrfm

Did you find anything?
Somebody else could guide me to check something specific?..

Thanks!!
Fiskbit
Posts: 891
Joined: Sat Nov 18, 2017 9:15 pm

Re: NESRGB? Garbled title screens/other graphical errors in some games.

Post by Fiskbit »

I can't help much here, but I definitely suspect some kind of issue related to the CPU reading from the PPU. Both SMB and Ice Climber do that for their title screens. Many of the bad values in your screenshots appear to have bit 2 cleared. The NESRGB sits between the CPU and PPU so it can manipulate values, so it's plausible it could be causing problems here, but I don't know enough to speculate about what is wrong.

Regarding EXT pins, those are all grounded inputs (and thus bridged) on the Famicom PCB, but on the NESRGB board, those are used as separate digital video outputs. If there were a problem there, you'd have RGB video issues, which is not the case.
Lelynx08
Posts: 3
Joined: Tue Apr 25, 2023 2:54 pm

Re: NESRGB? Garbled title screens/other graphical errors in some games.

Post by Lelynx08 »

Hey,
Indeed I conclude a bit the same thing…

But I found something weird.. the resistance near by a1 and a2 on the rgb board labeled 01d is showing continuity…
Which should not I think.. as it is 100*1000 ohms.. 100kohms if not mistaking..
So either there is a short.. either it’s dead.. I do not see damages around the points following tracks..

Could you check on yours if it’s the case?

Thanks!!!
tobeder
Posts: 1
Joined: Sat Apr 29, 2023 11:41 pm

Re: NESRGB? Garbled title screens/other graphical errors in some games.

Post by tobeder »

Hi! Recently I was having issues with my NES with NESRGB and after investigation, bridged the tantalum capacitor spot on the RGB lines of the NESRGB board as I found it could not be necessary with a cable that already has those, also fully recapped the console and was working fine again but after putting the metallic shielding I tested the system again and got this issue:

Image

The issue is the same with other games and already tried cleaning NES connector and cartridge as well. Could it be that the NESRGB board/PPU/VRAM could be damaged? If so how could I diagnose? What other suggestions do you have in order to diagnose?

Thanks in advance!
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