The multi av nes 2 and the cxa1534 model 1 genesis

[Drakon]

Two mods in one here. The first is my nes 2 which I've been having a lot of fun with lately. I've been giving my nes 2 a lot of love ever since I discovered it has just as clean of a rgb/s-video picture as the av famicom. This nes 2 was nothing special it started as your standard rf only nes 2 with jailbars in the rf video output. First I desoldered the rf box, and then I desoldered the nes 2 back plate by desoldering the ac adapter jack. I desoldered the back plate off of an av famicom and it's completely compatible with the nes 2 case so I was able to drop it in and solder and it fits perfectly in the case. The multi av has rgbs, s-video, and composite wired up (audio is another 2 wires that I'll do later when I have the time). The ppu has been desoldered with a socket installed. I also installed the chip that makes the rgb system able to use a powerpak. I discovered that on my playchoice pcbs (8 of them) they all come with the required chip to make a powerpak run on a rgb system. Kind of interesting. Here's pics of the nes 2









I'm also a big fan of getting s-video from a sega genesis. With regards to audio almost all versions of the model 1 genesis are the best. You can also s-video mod these systems but that's where they can be a bit of a problem. You get some annoying interference when you s-video mod a genesis. Don't get me wrong the s-video from the standard genesis mod looks very clean on my tv but I'm extremely picky with any form of interference.

The kits I use for rgb/s-video modding nes and famicoms has a video circuit that's basically just a lm1881 cleaning up the sync and a complete sony cxa1645 circuit. The model 1 genesis systems use the older cxa1145 chip which is...well....not the greatest. The way the av famicom kit works is you just feed it rgb, sync, 5v and ground and it will encode whatever you want to nice rgb and s-video. So I desoldered the cxa1145 from my genesis and wires up the kit to replace the 1145. Here's some pics comparing the original 1145 to the kit that's based on a 1645





















Really I don't think a genesis can get any of a cleaner picture than this. My capture card is EXTREMELY sensitive to interference so getting a picture this good means a lot.

[vlame]

How much time and money did these cost excluding systems? And why did you part out the av fc? Was it borked?

[Drakon]

How much time and money did these cost excluding systems? And why did you part out the av fc? Was it borked?

uhm I don't know how much time and money. I didn't "part out" anything the av famicom still works fine it just has no back plate. I have four av famicoms. The back plate from the av famicom has no damage I can always re-install it back into the av famicom if I like.

[Jamisonia]

What version of the genesis s-video mod are you using. I just did the Master System last night, which uses the same chip, and it look great, no interference whatsoever. I heard there are two versions, and one of them isn't that good.

[Drakon]

What version of the genesis s-video mod are you using. I just did the Master System last night, which uses the same chip, and it look great, no interference whatsoever. I heard there are two versions, and one of them isn't that good.

I did both s-video mods both had interference. These screenshots were taken from the better one. I'm pretty sure this interference is only found in the genesis (might also be in the aes).

[Ziggy]

I have done the S-Video mod to four different Genesis consoles in the last month. I was able to get them all looking the same. My model 1 and 2 with the CXA1145 looks just like my model 2 with the CXA1645 (and another model 2 with the MB3514) though I used two different circuits for them. They all look perfect though, no interference.

For the model 2 with the CXA1645, this is what I did for both Y and C:


http://www.gamesx.com/rgbadd/genesis3.htm

If you look in the datasheet for the CXA1645, this is what it says to do. So in my mind, this is the only way to do it. I also used this for the MB3514 and the picture looks identical.

Then I got a model 2 with the CXA1145. The datasheet says to do wacky things, so I started out by trying the above method just to see where I was at. The picture looked the same, but all white screens (like the Sega screen at the start or when you get warped into bonus stages in Sonic 2) would cause my TV to lose the signal. So, I gave this one a try...



Well, I didn't do that exactly. First, I built that amp for the Luma only and kept the Chroma the way it was (75ohm resistor, 220uf cap). Actually, I think I had to switch the resistor and cap around for Chroma, or switch the polarity of the cap. Secondly, those first two caps (100uf and 0.1uf) I didn't have on hand so I used a 220uf cap instead. The NTE85 doesn't seem to exist anywhere, I used a BC184L. Anyway, the result of all this was more saturated colors. I don't think it looked any better or worse, mostly just different (though my memory of it is getting fuzzy). But the white screen problem still existed, so I scratched it.

This is what I ended up using for the CXA1145. I made a schematic of it so it'll be easier to read...



Again, the NTE85 is MIA. I used a BC184L, easily obtainable. Also, it calls for a 27ohm resistor, but I didn't have one on hand so I used a 33ohm.

Using this amp got the picture looking just like my CXA1645 and MB3514, and the white screens work perfectly now. I scored a HDG model 1 shortly after and used this same amp, perfect picture, identical to the other 3 consoles.



So I'm just curious, which ones did you guys use?

[Drakon]

Those two circuits you posted are the exact same ones I used. The interference you get won't show up on a tv my capture card picks up a lot of things my tv doesn't.

Anyway I've since built myself an entire cxa1645 circuit. It worked fine but in sonic 2 I could see the background dark blue sky sideways refreshing. I wired the av famicom kit back to the system and the refreshing problem went away. There's something about the av famicom kit circuit that fixes that problem. I'm too lazy to bother re-creating the circuit it's easier just ordering another kit.

I did make a cool discovery though. For some reason when I leave the cxa1145 in the system and tap the rgb + sync at the av out port and wire that into the cxa1645 circuit the picture looks even better than when it's just the cxa1645 on its own....strange...here's some screenshots....they look amazing compared to the other ones...



























Since my capture card picks up every tiny piece of interference to have an image this clean is really amazing. Here's a simple diagram of how I wired things up



Of course the kit I'm using actually has the video parts installed. The red box with an X through it is the audio circuit which you don't need to build for this mod.

You can purchase this kit from here:

http://homepage3.nifty.com/F-LABO/ProductsList.html

I used sutocorp.com to proxy the order.

■ ＮＥＷファミコン マルチＡＶ化キット２　(音声分離回路用部品なし)
　１キット　６０００円（送料・振替手数料は別途）　

That's the version of the kit with just the video circuit parts.

[Jamisonia]

This is what I ended up using for the CXA1145. I made a schematic of it so it'll be easier to read...



Again, the NTE85 is MIA. I used a BC184L, easily obtainable. Also, it calls for a 27ohm resistor, but I didn't have one on hand so I used a 33ohm.

Using this amp got the picture looking just like my CXA1645 and MB3514, and the white screens work perfectly now. I scored a HDG model 1 shortly after and used this same amp, perfect picture, identical to the other 3 consoles.



So I'm just curious, which ones did you guys use?

I used the second mod on a SMS, and recently a model 1 Genesis. I used a 470uf Cap on the Genny like Jamma Nation mentions, and didn't notice any difference. I also used a 2N3904 for both, since I have a ton of those, and 22Ohm resistor. It worked perfectly fine.



Drakon
The Genesis does look a lot better with the CXA1645. I have read a few threads about people replacing them, but not having the easiest time with it. Yours if the first success I've read about. I just bought me a couple of them to do 32x s-video mods with.

[Drakon]

yeah the 1645 needs its own circuit. I built my own circuit at first it worked fine but in some games like sonic 2 the blue background you could see it refreshing which drove me nuts. This kit fixes that problem...I have no idea why...I'm too lazy to figure it out