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 Post subject: Re: Decode MMC3 PRG A16
PostPosted: Fri Oct 07, 2016 6:22 pm 
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Quote:
Is this repeatable with other games?

No, it happens only with this one.
That's why I'm thinking in put some solder on the contacts.
How do I say that in english? To foliate? To tin?? To stain?? :roll:

Quote:
If you have a conventional NES front-loader

No, it's a brazilian clone, just like this one.

I made some little modifications to get a better sound and image:
In the audio section I just made the circuit be mostly like the original NES, adding some resistors, capacitors and the inductor .
In the video section, I just took the transistor out of the board and soldered it straight to the PPU.
It's almost jailbar free and has no perceptible noise on the audio.
The audio is quieter, but not a big deal.
All the info for these mods are from here.
You guys are really great!! :wink:


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 Post subject: Re: Decode MMC3 PRG A16
PostPosted: Fri Oct 07, 2016 6:50 pm 
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You certainly could put a little solder on the contact, but I'd be worried that'd eventually bend the contacts and make them worse for other games.

"to tin" wouldn't be wrong, but I'd probably just explain it long-form to prevent confusion.

Do you have a microscope or something to get a good look at the contact? I'd think you'd be able to see a difference that would cause it to fail to make contact. Maybe a cold solder joint on the ROM? Sometimes just touching things with a multimeter moves things enough to make electrical contact again.


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 Post subject: Re: Decode MMC3 PRG A16
PostPosted: Fri Oct 07, 2016 8:20 pm 
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Well I got a magnifier similar to this one as a gift (weird history, maybe I tell later...), but I couldn't see any differences on the contacts.
Maybe I can try to take a look with a webcam.

That contact has really bitten me!!
I tested with the multimeter a dozen of times. I even plugged the board on a deactivated clone to do continuity tests.
A small piece of UTP wire behind the connector seemed to solve the issue, at least for now.
Looks like 22AWG gauge. I think I should try a thinner one, 28 maybe? A piece of 80 wire IDE cable?
I really would like a more definitive solution...

The contacts seem a little wear. Shouldn't they be golden?
They're mostly silver, I can see a little golden on them.
Maybe if I can find some conductive ink... how well would it resist to wear?

Anyway, thanks again for the help.
I was on it for a couple of days... Just felt like walking in circles.
I still need to finish that portuguese Zelda repro...
But that is the great thing to do things to yourself: no deadlines!!
The thing will be done when it's done, if done. :lol:


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 Post subject: Re: Decode MMC3 PRG A16
PostPosted: Fri Oct 07, 2016 10:00 pm 
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Location: Seattle
Fisher wrote:
I think I should try a thinner one, 28 maybe? A piece of 80 wire IDE cable?
I'd probably play around the 30-40ga range. But reflowing solder onto the contact isn't particularly wrong. Just be careful to not do too much.

Quote:
The contacts seem a little wear. Shouldn't they be golden?
They're mostly silver, I can see a little golden on them.
Yeah, that's a little worn. "hard" gold (30µ or so thickness) isn't directly attached to the copper PCB but instead to a layer of nickel.

Quote:
Maybe if I can find some conductive ink... how well would it resist to wear?
Abysmally, unfortunately.


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 Post subject: Re: Decode MMC3 PRG A16
PostPosted: Tue Oct 11, 2016 5:43 am 
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Well... even putting a gross layer of soldering did not help.
But it works fine if I put a piece of wire behind the edge connector.
Maybe I should change the connector, but for now only this game gives me this problem. Weird!!

I have patched it to have debug functions enabled.
The GameGenieGuy's program did give me some problems, so I searched a bit and figured out how to patch the code manually.
I'm posting the ips file here, in case someone is interested. It was only a single byte patched.
I used the PRG0 version, by the way.

Thanks. :beer:

Edit: It works fine with the GameGenie. I had removed the 220pf capacitor, it gave me no problem without the genie, but with it I had a strange status bar jumping problem. It was solved when I put the capacitor back. :roll:


Attachments:
File comment: Double Dragon II (PRG0) - Debug mode patch
DD2_Dbug.ips [14 Bytes]
Downloaded 27 times
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