Famicom RGB mod: noob question about ppu [updated]

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pipirisnaki
Posts: 7
Joined: Thu Jun 17, 2021 12:33 pm

Famicom RGB mod: noob question about ppu [updated]

Post by pipirisnaki »

Hi guys, i've just bought a famicom and saw some time ago that i could make an rgb mod. So, knowing nothing at all, i bought all materials to get the job done (following the guide by etim and other youtube videos).

While desoldering the PPU, i did something wrong: the green part of the pcb came out between pins 17-16, and maybe 15-14, as seen in attached image (already connected the 40 pin adapter).

Image

In etim tutorial, i saw something that those pins were connected to ground or something like that, so the question is this: It's ok if pins 17-14 touch each other with solder, or should i be worried and maybe have to find a method so the solder won't "auto join" with the flux in each point?

the mb model is CPU-GPM-02

pd: I know i have to improve the solder in the other points :D

Cheers!
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Last edited by pipirisnaki on Fri Jun 18, 2021 10:28 am, edited 1 time in total.
lidnariq
Posts: 11432
Joined: Sun Apr 13, 2008 11:12 am

Re: Famicom RGB mod: noob question about ppu

Post by lidnariq »

Pins 14-17 are completely ignored by the NESRGB mod - those pins are now reused to get the digital color out of the PPU. So you could even leave them messy.

If you want to be able to revert to stock and install the plain PPU back in the socket without the NESRGB mod, then leaving those pins floating probably will produce some graphical artifacts, but you might be OK even so.
pipirisnaki
Posts: 7
Joined: Thu Jun 17, 2021 12:33 pm

Re: Famicom RGB mod: noob question about ppu

Post by pipirisnaki »

lidnariq wrote: Thu Jun 17, 2021 7:44 pm Pins 14-17 are completely ignored by the NESRGB mod - those pins are now reused to get the digital color out of the PPU. So you could even leave them messy.

If you want to be able to revert to stock and install the plain PPU back in the socket without the NESRGB mod, then leaving those pins floating probably will produce some graphical artifacts, but you might be OK even so.
Thank you lidnariq, i thought that i've just messed it all!!
pipirisnaki
Posts: 7
Joined: Thu Jun 17, 2021 12:33 pm

Re: Famicom RGB mod: noob question about ppu

Post by pipirisnaki »

Ok, just a quick update. I was testing the results, got picture and audio... but the video quality it's not the best (i know i have to improve the soldering). As you can see in the attached gif, there appears to be some kind of wave in vertical axis? or something like vertical tearing. I don't know how to get rid of it.

Also, like the instructions, connected Y from RGBNES board to V_CS. I don't know if connecting V or other will make any difference.

GIF of the issue
https://imgur.com/bVTybFS

Right now, im testing with the rgb cable provided by etim, and a retrotink 2x SCART version.

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pipirisnaki
Posts: 7
Joined: Thu Jun 17, 2021 12:33 pm

Re: Famicom RGB mod: noob question about ppu [updated]

Post by pipirisnaki »

Ok, so i changed all cables, did a proper solder and all. When i went to test it, i got perfect video for at least 10 seconds, but after that, the screen becomes wavy again (vertical axis) as show in previous gif.
lidnariq
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Joined: Sun Apr 13, 2008 11:12 am

Re: Famicom RGB mod: noob question about ppu [updated]

Post by lidnariq »

Is it good for every first ten-ish seconds after power on? Or just the one time?
pipirisnaki
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Joined: Thu Jun 17, 2021 12:33 pm

Re: Famicom RGB mod: noob question about ppu [updated]

Post by pipirisnaki »

lidnariq wrote: Sat Jun 19, 2021 11:28 am Is it good for every first ten-ish seconds after power on? Or just the one time?
Just one time. I even tried to wait for 30 min with all unplugged, and always get the effect shown in gif. Maybe this have something to do with "powering de motherboard"?.

*In Tim's guide, the wiring diagram shows that for the new famicom model, 2 grounds must be connected... but i'm not sure if i have to wire also from 2 +5v points from power board to motherboard (that would be to pin 3 and 4, the 4th is vccout). Right now, i have 1 point +5v wired to pin 3 in motherboard, as shown in wiring diagram.
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lidnariq
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Joined: Sun Apr 13, 2008 11:12 am

Re: Famicom RGB mod: noob question about ppu [updated]

Post by lidnariq »

Those wiggles imply that the NESRGB is failing to find the correct pixel clock. (I don't know why). I'd maybe check the wiring you have for the 21.47MHz clock, and see if that helps at all
pipirisnaki
Posts: 7
Joined: Thu Jun 17, 2021 12:33 pm

Re: Famicom RGB mod: noob question about ppu [updated]

Post by pipirisnaki »

lidnariq wrote: Sat Jun 19, 2021 1:02 pm Those wiggles imply that the NESRGB is failing to find the correct pixel clock. (I don't know why). I'd maybe check the wiring you have for the 21.47MHz clock, and see if that helps at all
Yikes, you refer the wiring from the ppu right? the one marked in red in the attachment? Just checked continuity between PPU pin and adapter board, and no success :oops: (even if the diagram shows they are joint). I'll check de solder point and try again.

UPDATE: Just checked solder points and they seems to be ok (above and below board), i think the board doesn't connect the two points. Should i bridge with a little wire?

Thank you!!
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lidnariq
Posts: 11432
Joined: Sun Apr 13, 2008 11:12 am

Re: Famicom RGB mod: noob question about ppu [updated]

Post by lidnariq »

pipirisnaki wrote: Sat Jun 19, 2021 2:36 pm Yikes, you refer the wiring from the ppu right? the one marked in red in the attachment? Just checked continuity between PPU pin and adapter board, and no success :oops: (even if the diagram shows they are joint). I'll check de solder point and try again.

UPDATE: Just checked solder points and they seems to be ok (above and below board), i think the board doesn't connect the two points. Should i bridge with a little wire?
... Oh, I think etim changed the new PCB rev to try to make NTSC scanlines a constant 1364 master clock cycles long (instead of having one scanline out of that's 1360 pixels long). He wrote more about it here: https://etim.net.au/nesrgb/background_fault/
but eventually gave up on it. Maybe you just need to reflash yours?
pipirisnaki
Posts: 7
Joined: Thu Jun 17, 2021 12:33 pm

Re: Famicom RGB mod: noob question about ppu [updated]

Post by pipirisnaki »

lidnariq wrote: Sat Jun 19, 2021 3:15 pm
pipirisnaki wrote: Sat Jun 19, 2021 2:36 pm Yikes, you refer the wiring from the ppu right? the one marked in red in the attachment? Just checked continuity between PPU pin and adapter board, and no success :oops: (even if the diagram shows they are joint). I'll check de solder point and try again.

UPDATE: Just checked solder points and they seems to be ok (above and below board), i think the board doesn't connect the two points. Should i bridge with a little wire?
... Oh, I think etim changed the new PCB rev to try to make NTSC scanlines a constant 1364 master clock cycles long (instead of having one scanline out of that's 1360 pixels long). He wrote more about it here: https://etim.net.au/nesrgb/background_fault/
but eventually gave up on it. Maybe you just need to reflash yours?
Mmm it's suposed that i have ver 2.2 (bought the kit about a month ago). Guess i'll have to give it a try. Thank you for the help!!
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