Can the video signal of all Nintendo games be deinverted on the board itself?

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Can the video signal of all Nintendo games be deinverted on the board itself?

I've seen people offering ROMs or something for Donkey Kong boards that you could use to replace the original ROMs and the board would output normal video for use with a normal monitor, rather than inverted video for use with a Nintendo Sanyo or Sharp monitor.

Can this be done for any Nintendo board, specifically Punch-Out and Super Punch-Out? Would it be a matter of changing the code for the color PROMs and burning new ones, or is it more involved than that?

I know that you can use inverter boards with normal monitors, but that is an analog inversion, right? And as such, wouldn't it introduce some loss? I would think it would be better to have the problem corrected in the digital domain in the first place, and skip extra analog processing hardware.

If this can be done, I'm pretty sure that folks like Jrok, Spaeth, or 2600 (and probably others around here) could do it (it isn't something I could do, plus I don't have a burner). I'd be willing to pay if someone could do it. I want to put new monitors in my SPO machine.
 
You will still need an audio amp if your using a different monitor. But I would think you could change the values of the colors in the related ROMS to their inverted color equivalent. That should be the same as inverting colors (But a lot of work). The Sanyo inverter does a pretty good job of inverting and the monitor chassis can also me modified to invert, (If I remember correctly). To use a different brand monitor you can also buy an inverter and amp combo board from Mike's arcade, but I've heard mixed reviews on it. I wouldn't think altering the data before it was processed for display would produce any visual noticeable differences as far as quality is concerned
 
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You will still need an audio amp if your using a different monitor. But I would think you could change the values of the colors in the related ROMS to their inverted color equivalent. That should be the same as inverting colors (But a lot of work). The Sanyo inverter does a pretty good job of inverting and the monitor chassis can also me modified to invert, (If I remember correctly). To use a different brand monitor you can also buy an inverter and amp combo board from Mike's arcade, but I've heard mixed reviews on it. I wouldn't think altering the data before it was processed for display would produce any visual noticeable differences as far as quality is concerned

Yes, I know about the Mike's Arcade audio amp/inverter board, but I'd rather have Nintendo's broken-by-design gameboard fixed. Any extra processing in the video signal will inevitably introduce loss (maybe not enough to notice, but loss nonetheless).

I haven't decided what I want to do about an audio amp yet, but there are many options; and all of them are better options than Sanyo's little ultra-crappy monitor-mounted amps, which are solely responsible for the infamous "Nintendo hum" (which gets doubled in volume in a PO or SPO machine).
 
Yes, I know about the Mike's Arcade audio amp/inverter board, but I'd rather have Nintendo's broken-by-design gameboard fixed. Any extra processing in the video signal will inevitably introduce loss (maybe not enough to notice, but loss nonetheless).

I haven't decided what I want to do about an audio amp yet, but there are many options; and all of them are better options than Sanyo's little ultra-crappy monitor-mounted amps, which are solely responsible for the infamous "Nintendo hum" (which gets doubled in volume in a PO or SPO machine).

Spaeth was working on a Nintendo hum eliminator, but, well... As of the moment he is MIA
My Punch out doesn't really hum that bad at all, Not really even noticeable. Have you tried re routing the monitor power cords from the chassis away from the audio lines? Sometimes that helps. (I don't know why Nintendo did that). You probably already know this but recapping those amps can work wonders.
 
Spaeth was working on a Nintendo hum eliminator, but, well... As of the moment he is MIA
My Punch out doesn't really hum that bad at all, Not really even noticeable. Have you tried re routing the monitor power cords from the chassis away from the audio lines? Sometimes that helps. (I don't know why Nintendo did that). You probably already know this but recapping those amps can work wonders.
Recapping did nothing, and if you search this site or RGVAC for "Nintendo hum" you'll find that recapping did nothing for quite a few people (for some people it does help; there seems to be no rhyme or reason to it). The best Nintendo hum eliminator is a different amp. I've run the SPO board's audio through a pair of powered PC speakers before and the audio was perfect with not the slightest hint of hum.

I don't notice the hum when playing the game because the constant audio coming from the game drowns it out, but I hear it when the machine is on and idle; from a couple of feet away anyway. It is not a big deal; but it doesn't change the fact that the stock Sanyo monitor amp is crappy as the day is long; and there are far better alternatives out there.
 
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Recapping did nothing, and if you search this site or RGVAC for "Nintendo hum" you'll find that recapping did nothing for quite a few people (for some people it does help; there seems to be no rhyme or reason to it). The best Nintendo hum eliminator is a different amp. I've run the SPO board's audio through a pair of powered PC speakers before and the audio was perfect with not the slightest hint of hum.

I don't notice the hum when playing the game because the constant audio coming from the game drowns it out, but I hear it when the machine is on and idle; from a couple of feet away anyway. It is not a big deal; but it doesn't change the fact that the stock Sanyo monitor amp is crappy as the day is long; and there are far better alternatives out there.

Yeah, I see your point. I am biased though because I actually like the hum.
It reminds me that these games are from a time when the electronics in these games were not perfect and had hum, glitches, bad engineering etc. In short I have accepted all of my games' flaws and wouldn't have them any other way :) Back to the subject though. If you do decide to get those ROMs keep us posted. It would be interesting to see that in action.
And sorry I wasn't of any help.
 
Arcades were noisy places, so I never noticed the Nintendo hum in the '80s, so I'm not nostalgic for it at all. Plus it is pretty much only a Nintendo thing; my other machines don't hum.

I won't fault you for being a purist though; as I'm sort of the same way; though not to the extent of wanting to preserve the Nintendo hum, or the broken-by-design color inversion which was just the result of Nintendo being jerks (trying to corner the market on replacement parts, rather than complying with de facto industry standards like most other arcade companies did).

Nintendo is lucky that they had some monster hits in their catalog, or operators probably would have told them to go pound sand, rather than put up with their 100 volt, undersized buttons, color inversion, weird marquee lamp, outboard audio amplifier, weird undersized T-molding foolishness.
 
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though not to the extent of wanting to preserve the Nintendo hum, or the broken-by-design color inversion which was just the result of Nintendo being jerks (trying to corner the market on replacement parts, rather than complying with de facto industry standards like most other arcade companies did).

Nintendo is lucky that they had some monster hits in their catalog, or operators probably would have told them to go pound sand, rather than put up with their 100 volt, undersized buttons, color inversion, weird marquee lamp, outboard audio amplifier, weird undersized T-molding foolishness.

Very true sir, And dont forget the 5/8" offset T-molding on the USA built cabs and the special pushbutton switch holders. Still though, you gotta love Nintendo. They did do things their own way and got away with it. I think they are still of the same mind set with things like the Wii. :)
 
On PO(and SPO, Arm Wrestling, Playchoice, Vs) invert the signal on the PCB. They natively output a non-inverted signal, then it goes through an inverter and then an amp, IIRC. So, yes you can modify the PCB to output a non inverted signal. I don't recall there being a special pad or anything that automatically did this like there are on some of the previous Nintend boards.

You could probably also swap the proms with inverted data.
 
On PO(and SPO, Arm Wrestling, Playchoice, Vs) invert the signal on the PCB. They natively output a non-inverted signal, then it goes through an inverter and then an amp, IIRC. So, yes you can modify the PCB to output a non inverted signal. I don't recall there being a special pad or anything that automatically did this like there are on some of the previous Nintend boards.

You could probably also swap the proms with inverted data.
How does MAME display the correct colors to an ordinary monitor? If I understand correctly, the colors are correct in the PROMs, then inverted before leaving the board, then inverted again back to correct in the Sanyo monitor's circuitry. So shouldn't MAME be outputting inverted colors since it doesn't include emulation of the Sanyo monitor's circuitry? Did they do some sort of workaround?

And how hard would it be to burn some color PROMs with inverted color data? I wouldn't want to make any permanent changes to the board; but I wouldn't mind swapping some socketed chips around.
 
This is a very summarized so it's easier to understand, not to be used for anything else.

Proms -> inverter -> Sanyo
The Sanyo uses inverted video. There are acutally spots directly on the Sanyo board the you could populate so that it could take non inverted video.

MAME uses the data before the inverter.

It wouldn't be too hard to burn the inverted data. You just need someone to take the time to invert the data in the proms and then test it. I was going to add this option on my prom converter board, but didn't think it would really be used so opted not too.

It's also possible that you could just swap a component or two (for each color) in the inverter section to get the correct output.
 
Now.. if I remember correctly. I think it was Spike @ lupine systems who made a PROM inverter board. It was a board that plugged into the PROM sockets, the PROMs plugged into the the board and the outputs of the PROM's went through a 74LS04 inverter then to the normal PROM output pins. So it inverted the digital PROM output before it went to the color output resistors. I have no idea how well that worked tho'. But looking at it... there's a pull up on the PROMs outputs for RGB so when the PROMs are deselected the output goes high ( full on ) ! So I'm not sure just how well that'd work without also replacing those resistors too.

- James
 
Now.. if I remember correctly. I think it was Spike @ lupine systems who made a PROM inverter board. It was a board that plugged into the PROM sockets, the PROMs plugged into the the board and the outputs of the PROM's went through a 74LS04 inverter then to the normal PROM output pins. So it inverted the digital PROM output before it went to the color output resistors. I have no idea how well that worked tho'. But looking at it... there's a pull up on the PROMs outputs for RGB so when the PROMs are deselected the output goes high ( full on ) ! So I'm not sure just how well that'd work without also replacing those resistors too.

- James

That was for DK. Similar circuit, but not plug and play. I'm not sure I follow you on replacing those resistors though. You need those for the different shades of the color.

Hopefully, you remember basic transistors better then me. What if you replace the PNP at the end with a NPN transistor?
 
That was for DK. Similar circuit, but not plug and play. I'm not sure I follow you on replacing those resistors though. You need those for the different shades of the color.

I don't mean the color resistors themselves, but the pull-up after the color output, R72, R76 & R78. When the prom is disabled these will force the output to high. These would need to be replaced with pull downs.

Hopefully, you remember basic transistors better then me. What if you replace the PNP at the end with a NPN transistor?

That makes me think.... just drive the RGB output directly form the digitally inverted color PROM with the addition of the pulldown ;) Remove the transistors completely.

This of course means board mods....

- James
 
Actually.. thinking about it some more...

Something like this should work ;)

Invert the color PROM output with the 74LS04, and ensure there's a pull-up on the input, so when the PROM is de-selected the input to the LS04 is pulled high and the output then goes low. It would then only have to fit in the socket.

- James
 

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Actually.. thinking about it some more...

Something like this should work ;)

Invert the color PROM output with the 74LS04, and ensure there's a pull-up on the input, so when the PROM is de-selected the input to the LS04 is pulled high and the output then goes low. It would then only have to fit in the socket.

- James

You wouldn't want to build something like that would you?

In any event, thanks for the information.
 
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