JAMMAfying another console, having video issues - This time, the JAMMA SNES!

[Lemony Vengeance]

Hey all,

I'm working on another JAMMAfied console, The SNES. When I'm done, I plan on putting together a HOW TO and putting it up here. RIGHT NOW, I'm stuck. Yep, RGB issues. AGAIN.

Here's what it looks like when I pull the video from the AV out, nothing in between:



Dark.

I tried the N64 RGB amp from the MMMonkey site, it's DIM, but super saturated, but then slowly gets darker over time.

I then tried the PCE RGB amp (I had a spare kicking around). No change.

THEN, I tried 220uf caps on the RGB lines (negative toward the edge) and it looked a bit more colorful, but not bright. I added 75 ohm resistors before the caps (but not between the caps and the edge) and.. well, this is what it looks like, compared to my PVM. I have two SNES consoles and two SF2 carts so they were taken nearly at the same time:

I did a bit of research and found out there's a few revisions of the SNES. I have the SNS-CPU-GPM-01 motherboard with the S-ENC A encoder, which is the ROHM BA6592F. Pins 20, 21 and 22 are R, G, and B respectively, but according to the schematics, the RGB lines split before they hit the encoder. One goes to the encoder, and the other goes directly to the AV socket on the back. Here's a link to the schematic of the encoder, and the SNES in general:

http://www.mediafire.com/?2x9erpy79q69o8t

I found this post on the Sega 16 forum that talks about an amp:

**EDIT**

after looking through the schematics, the above circuit it built into the SNES:

That's all I've found. Am I off the beaten path? Is there an easier way? I'd rather not venture out of this forum since a specific someone, who just happens to be the most vague guidance giver (and just so happens to love hot glue) frequents the other places and I really don't want to interact with him.

Any additional information or guidance or anything else would be most appreciated.

 

[dipindods]

omg make me one!!!!!!! i wish i was good like you i could never do this

 

[Kid Panda]

omg make me one!!!!!!! i wish i was good like you i could never do this

Never believe that, you have to practice and start somewhere brotha!

 

[Lemony Vengeance]

soo, I just looked over that RGB circuit I posted.. turns out, this circuit was built into the SNES in the first place:

from the schematics:

according to this, the RGB lines split before they hit the encoder. One goes to a .1uf cap then to the encoder, and the other goes directly to the AV socket on the back for each color. this explains why the color is much more dim when pulling it directly off the encoder..

 

[Lemony Vengeance]

so I just talked to the guy that started this thread (via twitter.. of all places):

http://nfggames.com/forum2/index.php?topic=4878.0

and he told me the Amp he posted in there worked just fine for him:

I'll make this up tomorrow and test it on my MS9

 

[Lemony Vengeance]

ok, tried this amp. didn't work.


officially out of ideas.

 

[skate323k137]

I know with my SNES on a PVM I just use 220uf caps, then straight to the monitor.

Maybe try a 220uf cap on each color right before that new amp?

Good luck man, wish I could be of more help.

 

[Xian Xi]

You don't even need an amp. Just put a switch on the +5v leg of the video encoder to prevent it from pulling when using RGB.

 

[Lemony Vengeance]

You don't even need an amp. Just put a switch on the +5v leg of the video encoder to prevent it from pulling when using RGB.

or I could pull the encoder off completely since it's not being used. OOR cut the trace to the VCC leg of the encoder.

 

[trenog]

or I could pull the encoder off completely since it's not being used. OOR cut the trace to the VCC leg of the encoder.

Did you look at that amp I posted to chat earlier?



Except that the large resistors are supposed to be 5.1M

 

[Xian Xi]

Did you look at that amp I posted to chat earlier?

View attachment 8718

Except that the large resistors are supposed to be 5.1M

Pull up resistors pre-amp?

I've used this amp before and it works well.

 

[Lemony Vengeance]

minus the resistors and caps PRE AMP, this amplifier does not work well for this application.

I will need to pick up resistors and such later on when I get more of this IC in my hands.

 

[Terot]

I rarely drink but have been tonight so here is my drunk question: "4 Y U do dis bro? I can makz U IKEa tbl 4 da cheapz & put a TV & SNES turbo arcade stick on it! Save youz $ for da real shit!"

Please feel free to disregard my drunken ramblings.

 

[Lemony Vengeance]

I rarely drink but have been tonight so here is my drunk question: "4 Y U do dis bro? I can makz U IKEa tbl 4 da cheapz & put a TV & SNES turbo arcade stick on it! Save youz $ for da real shit!"

Please feel free to disregard my drunken ramblings.

many people ask me why I do shit. I look back at them and say, "Why not?"

 

[Lemony Vengeance]

or I could pull the encoder off completely since it's not being used. OOR cut the trace to the VCC leg of the encoder.

did both. no change. :/

 

[shadows]

Have you tried on another cab?

 

[Lemony Vengeance]

neo 29, NAC and blast (MS-2933)

 

[shadows]

So I guess everyone before hand were fine with the overly saturated and dark colors. As all guides Ive seen on hooking up an SNES to a cab never used any amps of any kind.
Ill do some testing of my own later today and see what I get.

 

[Lemony Vengeance]

So I guess everyone before hand were fine with the overly saturated and dark colors. As all guides Ive seen on hooking up an SNES to a cab never used any amps of any kind.
Ill do some testing of my own later today and see what I get.

I asked airthrow (the last guy to make and sell them here) and he had no idea what I was talking about.. even told me I needed the sync separator circuit (you don't. NTSC SNES have C-sync out of the gate) and that's why video was dim.

Proved him wrong.

Talked with the guy who gave me the transistor amp above.. didn't work. thanks for your assistance in this man. The plan is to put this out on the forum as a HOW TO so people can make their own.

 

[shadows]

Yea an LM1881 isn't needed in theory, and it sure wouldn't do anything to the colors even if one was used.

 

[leonk]

Let me try and take a stab at it. A lot of console users that dabble with RGB output 15k RGB to a Pro broadcast monitor (like Sony PVM) which can be had for a song and put out the best picture out there in CRT-land. Better than any Trinitron and def better than any arcade monitor. Lots of info out there for that but you have to compensate for the differences.

I think the main difference is voltage of input (<1v for TV and 5v for arcade monitor) but some arcade monitors do support the lower voltages. The other thing to keep in mind is that Nintendo really messed things up with the SNES. Unlike other systems, depending where in the world you are, the RGB cable you need to make differs!

So, if it was up to me, I would tackle it this way:

1) pretend the arcade monitor is a PVM and try to feed it signal as such. Here are cable schematics for the SNES (as well as other consoles): http://members.optusnet.com.au/eviltim/gamescart/gamescart.htm#snes

2) If that fails, then use a professionally made product to acheive what you want. This comes to mind: http://members.optusnet.com.au/eviltim/vga2arc/vga2arc.htm

Version 2 with ability to purchase: http://etim.net.au/scart2arcV20/scart2arc2.htm

 

[leonk]

One for sale in USA:

http://shmups.system11.org/viewtopic.php?f=4&t=48220

 

[shadows]

With just 220uF caps and 75ohm resistors on the lines. Colors are fine, but of course not as bright/vibrant as it could be.

And thats off the encoder in a mini/Jr.

Gonna give it a go with an amp I have.

 

[leonk]

The 75 ohm resistors are needed in the snes jr to add the missing RGB circuit. If you have the original SNES, all you need is the caps.

Don't you control color and brightness using remote board on arcade monitor?

 

[dipindods]

yeah just sell it to me

such a awesome idea nice work!!!!!!!