Xref: utzoo sci.electronics:16189 rec.games.video:11334
Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!usc!julius.cs.uiuc.edu!news.cs.indiana.edu!iuvax!bsu-cs!bsu-ucs!00nacooper
From: 00nacooper@bsu-ucs.uucp (Ho Ho Ho. Merry Christmas from SocrateS)
Newsgroups: sci.electronics,rec.games.video
Subject: Re: Nintendo Cartridge Internals
Message-ID: <52032@bsu-ucs.uucp>
Date: 10 Dec 90 17:58:52 GMT
References: <1990Dec10.172238.18313@msuinfo.cl.msu.edu>
Organization: Ball State University, Muncie, In - Univ. Computing Svc's
Lines: 78

In article <1990Dec10.172238.18313@msuinfo.cl.msu.edu>, gurney@eecae.msu.edu (Eddy J. Gurney) writes:
> Last weekend I was at a local Swap'N'Shop (Amateur Radio related) and I
> bought three "non guaranteed to work" Nintendo carts for $20.00.  They
> apparently were from a video store that rented the things, and had gotten
> trashed somehow.  I took three of the nine or ten the guy had, figuring it
> wouldn't be too hard to clean the contacts or whatever, assuming it was 
> something simple like that. =)  Anyway, two out of the three don't work
> at all; one of them is screwed up - the graphics are all "trashed" - kind
> of like what happens when your programs accidentally starts storing stuff`
> where the video memory is mapped. :-)  Anyway, SOMETIMES, the last game is
> playable, and the characters are just slightly skewed, other times it's
> hopeless.
> 
> I took apart one of the non-working cartridges, and inside there was a
> VERY tiny circuit board - which surprised me from the size of the plastic
> case.  First question: Are all the circuit boards for Nintendo cartridges
> the same?  This one says (C)1987 Nintendo on it, and has four ICs, two
> resistors, and a capacitor.  It also has two "jumpers", one labeled "H"
> the other "V".  The "H" jumper is connected while the "V" jumper is open.
> Second question: What does this select?
> 
> The four chips are as follows:
>  . 74HC161 - which is a 4-bit binary counter with asynch reset.  It is
>              capable of being loaded also.  Third question:  Any idea what
>              they do with this?  Is it used to divide the clock from the
>              main NES box?  This one is easy to replace if it's the
>              problem (although I doubt it... the easy ones never are the
>              cause of problems!)
>  . One labeled (C)1989 Nintendo (16 pin DIP)
>              I assume this is a PLA; probably something to do with their
>              monopoly on requiring something special in the cartridge for
>              it to work in the NES.  Fourth question: Anyone know any
>              specifics about this chip?  (Or maybe references to other
>              articles on it?)  If this chip is the bad one, I presume it's
>              impossible to get, and I'm SOL.
>  Finally, there are two 28 pin DIPs that appear to be ROM's.  One is labeled
>  as PRG, the other as CHR.  The PRG chip says "M38128B-13" on the second line.
>  The CHR chip has six numbers on the second line; unfortunately, I'm doing
>  this from memory and I can't remember what it says.  I suppose it's
>  conceivable the ROM's are fried from a static zap to the connector.  Anyway
>  to tell?
> 
>  The cap appears to be a bypass cap from the top of the circuit board to the
>  bottom.
> 
> Anyway, anybody have any info on what all this stuff is?  Maybe pinouts on
> the ROM's (if that's what they are?)  Anybody else take apart any other
> cartridges?  Are they similar to this, or does each manufacturer use their
> own boards?  I haven't taken apart the other two yet; I pretty much hacked
> the first case, thinking the circuit board was going to be big.  If they're
> all this small, it's a simple matter of sticking a screwdriver to pry the
> case open near either of the screws at the connector end.  Slowly push in the 
> screwdriver til the case pops - this allows enough room to let the cartridge
> slip out, and the only damage to the case is that one of the screws is
> missing.
> 
> Any information or references would be greatly appreciated;  I'll post a
> summary to the net if I receive any replies.
> 
> aTdHvAaNnKcSe,
> Eddy J. Gurney, N8FPW
> 
> --
>       Eddy J. Gurney, N8FPW           THE ECCENTRICITY GROUP
> eddy@jafus.mi.org -- gurney@frith.egr.msu.edu -- 17158EJG@MSU.BITNET
> (Preferred)          (But this is OK too)     (Only if you have to :-)

I'm not sure about the technical side of things, but as for the size of the 
chips, i have opened up a couple, and they are all small(at least the 
Nintendo, I don't know about Tengen games) There is a way to take out a chip 
without doing ANY damage to the chip: on the reverse of the game, there are 
screws(on the older games) or another kind of screw(on the newer ones). I'm 
not sure how to do this on the newer games, but you can use a very small
screwdriver to take apart the older games. The newer ones may have rivets
instead of screws, I'm not sure about this. Well, I hope this helps a little.


						Nathan Cooper