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PostPosted: Sat Oct 08, 2016 5:07 am 

Joined: Sun Sep 19, 2004 11:12 pm
Posts: 21212
Location: NE Indiana, USA (NTSC)
As I understand it, the NES Game Pak connector pitch is 2.50 mm from the center of one pin to another, while post-patent clone consoles and cart programmers (e.g. Kazzo) are more likely to have a connector with the more common 2.54 mm (0.100 inch) pitch. From the center to the edge of a 36-pin-per-side connector, this error accumulates 0.04 mm * 18 = 0.72 mm.

One solution that I've suggested a few times is to cut 0.7 mm out of the middle of a 2.54 mm connector, where the otherwise unused expansion pins go, so that the error accumulates only across the CPU half or across the PPU/CIC half. With less distance over which to accumulate, the error would reach only 0.36 mm. But that's not the solution I was planning to discuss in this topic.

Another solution that I thought of this morning is to make cartridge boards using a 2.52 mm pitch, splitting the difference between an authentic NES connector and a clone connector. How practical is it to design a board with 2.52 mm pitch?

PostPosted: Sat Oct 08, 2016 6:10 am 
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Joined: Fri Nov 12, 2004 2:49 pm
Posts: 7678
Location: Chexbres, VD, Switzerland
tepples wrote:
How practical is it to design a board with 2.52 mm pitch?

It is just as practical as any other pitch. Since the pins are drawn as copper on the PCB directly, there is no limitations when it comes to it when designing the board. However what is hard is designing the connector on console side.

PostPosted: Sat Oct 08, 2016 2:12 pm 
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Joined: Mon Sep 20, 2004 6:04 am
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Location: Indianapolis
Interesting idea, but I don't think the 2.54mm connectors have been a problem yet. I suppose it could if the connector people are using went away and was replaced by one with wider pins. I modified my NES to use a 2.54mm pitch connector and I haven't had a problem playing Nintendo boards and testing hundreds of my own GTROM boards (edit: well OK, that's through a Game Genie so that only says the GG works reliably). And I'm pretty sure the Analogue NT uses a 2.54mm pitch, with how expensive that was I'm sure people would have raised a stink if they had problems with carts not working on it.

I remember I was able to make some carts not work by sliding it to one side, but it seems like in practice (just inserting it normally) this simply never happens.

The AVS uses a 2.5mm pitch connector, but it has trouble with some carts because the insertion depth isn't enough. If it's not one thing, it's another. :| That sucks, but at least in that case the connector is user-replaceable.

You could also reduce the chance of shorting by making the pins on the cart more narrow. But I'm still taking the "if it ain't broke, don't fix it" approach.

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