Another Rgb Nes

[mvsfan]

Success - somewhat.

Over the weekend i installed the Rp2c03 in my nes, and i have been listening to the music from Arkista's ring since. now im getting excited because the hard part is done and i also know that the PPU isnt dead. I also replaced the 74ls373 with a 74hc373 and i socketed it in case it ever needs to be replaced. i dont see the logic in replacing an ic and not socketing it.

i have some things to take care of but when i get a chance to disassemble the nes again  ill post some pics of it.

also ive seen a lot of different ways to get the old ppu out. best way ive found is to use a heat gun with a pencil tip. flip the board over and pass the heat gun over one set of legs then the other then back to the first until the weight of the chip basically causes it to fall out. be careful you dont get things too hot or youll start lifting traces. Practice on some junk first, and be careful not to overpass and heat up your other components or they will fall out too.

so this is what ive done sofar, and it WORKS. im excited.

all i have do now is hook the video amp up and connect it all to the scart socket on the back of the nes.

why did i use a scart socket? simple, i had a panel mount socket from when i added one to my arcade cabinet i ordered an extra.

also now that i think about it i dont need any kind of special cable, just a simple fully wired scart to scart will do.

[mvsfan]

one last thing. any ideas on how i should hook up the video grounds? ive read that lifting pin 17 and using that for your video ground tied into the amp and the scart socket eliminates most interference and JB. could someone please confirm that?

also would you want to tie only your video ground going to the scart socket to pin 17, and ground the amp to the nes chassis, or is their some better way?

thanks.

[mvsfan]

ive almost successfully built an rgb nes. i chronicled it over on drakons forum. he helped out a lot.

im using a scart to yuv box i got off of ebay. thats my setup.

this rgb nes is done, the only problem is that i cant get it to sync at all. i get a b/w rolling picture.

ill explain what ive done.

replaced ppu with rp2c03b

bent up 14 15 16 17 and 20, attached sheilded wires and ran rgb through an ultimarc amp. i pulled power for the amp as well as the amp ground from pins 20 and 40 on the ppu. 14 15 and 16 go through the ultimarc amp to a scart socket. pin 17 is wired to the sheilds on rgb, and then straight  to green ground on the scart socket.

i didnt run sync through the amp instead i ran it through an lm1881 circuit, through a 220uf cap  and then to pin 20 on the scart.

all of this then ends up at the yuv box.

that is how its wired up right now. from here on ill tell you what ive tried, with no results.

ive tried it with the 220 cap, without it, with the 1881 and without. through the ultimarc amp, and not through it. ive tried hooking up ground to other pins on the scart.

once for a breif second, i did get a good screen, but it didnt hold long and i havent had one since. its just gone back to rolling.

[Game-Tech.us]

I'm in the middle of the same project, but I found the YUV converter was my first issue.
I was using it to test the rgb out on an 19" lcd that has component, but no rgb, it also wouldn't sync properly.
Then I hooked it up to the rgb/vga in of my front projector and got a perfect picture, so I quit using the YUV converter.
I ended up buying a sony pvm-2030 to test with, mostly because its the exact same monitor the customer has.
I haven't gotten in to it far enough to test out the various claim of what gets rid of jailbars, the last I heard Drakon started using the japanese kit and that eliminated most of them, so it could be using the sony cxa chips as an RGB amp is the best solution.
Getting that kit from japan is proving to be prohibitively expensive so I plan to eventually have my own boards made here for much cheaper.

[lalin]

I wanted to share with you guys what I did.

Because you only have one RGB->Component converter (or projector AND console modding can be addictive (you will very probably want to do this with other consoles), I decided that my consoles' video signal will be output via a Cat5/RJ45 cable.
The reason is that these cables are sooo easy to make and reliable.
Then, on the converter side, I made a cable converter from RJ45 (female) to SCART (as my RGB->Component only take SCART).
That way I can "multiplex"/switch RJ45 cables with only 1 RGB->Component.

If you use this method, be careful that your RJ45 cables don't be too long or the signal will get distorted.  It happened to my with my Genesis/Megadrive RGB mod.

I hope this little info be of use to you.

Game on brothers!

[mvsfan]

ive basically quit posting about this since i havent had any results. i have managed to aquire a couple extra chips in the meantime though. its not the chip.

[mvsfan]

a small update. ive basically stopped working on this, as ive solved the problem (sort of).

Ive determined that my sony wega tv is the problem, NOT the nes. how did i figure this out? so i recently went to plug in my supergun that i hadnt used in a long time into my wega, to test an aerofighters board i was going to sell. so, i switch it on and guess what, aerofighters is doing the exact same thing as the rgb nes. picture rolling, color cuts in and out, wont sync for shit. The supergun had always worked fine on the old sylvania tv, so i pulled out the old tv, and yes, aero fighters was working fine. so, instantly i got the idea to try the nes. i soldered on a scart socket to the s-video converter inside the supergun, plugged it in, and the nes WORKED fine on the old sylvania. after all that time i thought it was the nes i kept resisting the urge to switch tvs cause the wega is so heavy.

so, its the wega. ive since read that the rgb nes, and some jamma boards, doesnt output a true 60hz signal, and the wega cant deal with that off signal because its very picky.

with this in mind, is it possible to add some part to the nes to make it sync a true 60hz, or on the other end, is it possible to adjust the wega through the service menu or an internal pot, to make it sync with the nes?

thanks, for your time.

[mvsfan]

I completely re-wired this nes using a njm amp and a new lm1881.

Im still having a small sync issue.

I have an awesome picture out of the nes now, whereas before i couldnt get any video at all.

But - this awesome picture very slowly rolls from top to bottom. It rolls so slow that i can almost play games on it.

Any suggestions on how to get it to stop rolling?

[mvsfan]

as you can see it has nice video. but it rolls ever so slowly.

[TheNameOfTheGame]

as you can see it has nice video. but it rolls ever so slowly.

Nice picture..I know you had to have tried adjusting the TV's v-hold, right?  With such a slow roll, I would think the TV could just be adjusted a little.

You are taking sync from pin 21 and then running it through the LM1881?  That should work I would think.

[TheNameOfTheGame]

So what you are saying is that it is no different with the LM1881 or without it, right? 

Take a look at this datasheet http://nootropicdesign.com/ve/downloads/LM1881.pdf

Which of the outputs are you using to feed the tv?  You may need the inverted vsync output.

[Drakon]

This system was mailed to me and I fixed it.  Sync ground wasn't wired up.