Ways to play Famicom games on an NES

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Bregalad
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Re: Ways to play Famicom games on an NES

Post by Bregalad » Mon Jan 08, 2018 6:19 am

GreyRogue wrote: I took some pictures of this several weeks ago and never got around to replying to this like I meant to. In case you're still curious:[...]
So, yes, it does have a defeat mechanism. It looks like it also has all the traces in place for an official lockout chip (or pin equivalent), which would be preferable, but I've been loathe to cannibalize a cart to do so. I believe it has all the signals pass thru except for audio, so this one could be modded pretty easily to be ideal. However, I'll probably wait to see what the INL one looks like before modding this one.
That's like exacly the same converter my brother-in-law had and whose I tried to draw the schematic back in 2005 here. I however never understood at all how it works.
As an aside, does anyone know if it matters that the audio pin going from the Famicom to the cart is left floating? Should this be terminated in some way or does it matter? I'm unfamiliar with how the carts mix in this audio, or how an audio modded NES would would mix it in for the famicom carts that just pass it through. Do either of these cases amplify the floating noise signal somehow, where terminating the input would improve it? As I said, I haven't looked at the circuits at all.
I could be mistaken, but from what I remember : It shouldn't matter that the audio pin is not terminated, famicom carts typically have just a bridge on an already amplified audio. Famicom carts with expansion audio mix their own amplified audio into it. The signal is not amplified by the famicom after leaving the cart and goes straight to the output or RF modulator.

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rainwarrior
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Re: Ways to play Famicom games on an NES

Post by rainwarrior » Mon Jan 08, 2018 6:35 pm

Yes, all the expansion carts I have will output their audio fine without the audio input in being connected to anything.
lidnariq wrote:The Famicom-to-NES adapter often connects the famicom cart edge AUDIO TO MODULATOR pin to a random one of the NES EXP pins. Usually people just put a resistor between that random EXP pins on the NES cart connector and NES expansion port pin 3.
I thought most Famicom to NES adapters don't connect the audio loop at all? Why would they connect to any EXP pin? (And why 3?)

The PowerPak and Everdrive use EXP 6 for output. I would imagine that INL's prospective converted will connect it there as well. (That is of course how I modded my own JOINT converter, since I already had the mod in place for my powerpak.)

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Re: Ways to play Famicom games on an NES

Post by lidnariq » Mon Jan 08, 2018 7:20 pm

rainwarrior wrote:I thought most Famicom to NES adapters don't connect the audio loop at all?
I'd been given the impression that a substantial minority of converters did connect them, per the wiki:
nesdevwiki:Cartridge connector wrote:EXP 2 : Used by some Famicom to NES converters as audio input, because this pin is just straight ahead of the Audio In pin.
Why would they connect to any EXP pin? (And why 3?)
Not EXP. Expansion. The connector on the bottom.

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rainwarrior
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Re: Ways to play Famicom games on an NES

Post by rainwarrior » Mon Jan 08, 2018 7:36 pm

Ah, okay.

Yeah, I'm really surprised to see that note about EXP 2 on the Wiki. I guess it's been there since 2009.

I just wouldn't have assumed any converters would do anything at all with an EXP pin prior to the popularity of the "PowerPak audio mod" with EXP 6. Would be really curious to actually see one that does this!

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Re: Ways to play Famicom games on an NES

Post by GreyRogue » Mon Jan 08, 2018 8:56 pm

rainwarrior wrote:Yes, all the expansion carts I have will output their audio fine without the audio input in being connected to anything.
It wasn't really a question of whether or not it works with it floating, so much as if it was adding noise, as I was concerned the floating pin might be mixing in extra noise (On the actual Famicom, it isn't floating). I was thinking like how if you ever have powered speakers unplugged, they can hum or buzz if the input cable isn't hooked up to anything. I believe this should only happen if the line is amplified without any signal at an amplification stage (either in the cart or in the NES). Sounds like others have looked at this, though, and this isn't an issue.

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