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Help to restore a Sonic 3 cartridge [Solved]
http://forums.nesdev.com/viewtopic.php?f=23&t=17089
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Author:  lidnariq [ Mon Feb 26, 2018 1:30 pm ]
Post subject:  Re: Help to restore a Sonic 3 cartridge

Fisher wrote:
By the markings and format of the other parts, I suppose they're resistor bars. (is this name correct?)
"SIP Resistor network" is probably the most horrifically verbose technical way of describing it.

Author:  Fisher [ Mon Feb 26, 2018 5:04 pm ]
Post subject:  Re: Help to restore a Sonic 3 cartridge

Looks like I'm stuck with SRAM. :cry:
In no way I could make the FeRAM save again :-(.
I think I'll use a battery circuit like this one.
How good/bad it is?
Should I add an elctrolytic capacitor?
If so, where and what voltage/value?

lidnariq wrote:
"SIP Resistor network" is probably the most horrifically verbose technical way of describing it.

Yes, this sounds kind of weird, but if it's the correct way, I'll stick with it.
Thanks for clarifying.

Talking about technical correctness, the MegaDrive schematics I'm using as reference don't shows A0 on the cartridge or the expansion slot. Heck! it don't shows it even on the 68k!!
Is it correct? Is the A0 line internal to the 68k processor only or it's drawn using some kind of different notation?

Anyway, thanks guys!!
I'm almost finishing this thanks to you!!
You're all great!!

Author:  lidnariq [ Mon Feb 26, 2018 5:16 pm ]
Post subject:  Re: Help to restore a Sonic 3 cartridge

"SIP resistor" or "resistor network" are both mostly correct, too.

68k uses 8-bit byte addresses, but has a 16-bit word bus. So A0 is hidden inside the /UDS and /LDS strobes, which are ultimately only pertinent for writes- hence why there are /UWR and /LWR signals on the Genesis's card edge.

Author:  Fisher [ Tue Mar 06, 2018 5:57 am ]
Post subject:  Re: Help to restore a Sonic 3 cartridge [Solved]

Thanks guys. That's it!!
It's working fine for about a week and the kids ara very happy. :-)
I used an SRAM and that circuit do plug the battery.
I could get an small battery support from an old notebook motherboard.
This is the end result:
Attachment:
File comment: S3 Front
d54ca08c-b6ef-44c5-bfaa-f6e1f471304b.jpg
d54ca08c-b6ef-44c5-bfaa-f6e1f471304b.jpg [ 125.03 KiB | Viewed 405 times ]

Attachment:
File comment: S3 Back
897937c0-ce29-4f93-aa75-16806a8eecd0.jpg
897937c0-ce29-4f93-aa75-16806a8eecd0.jpg [ 150.27 KiB | Viewed 405 times ]

I could avoid using that blue wire if I removed th SRAM and put that small resistor soldered right above th IC, but the kids were very impacient to play and save in the game. :D

I have some other doubts related to the MegaDrive, but I think I should create another thread...
A big thank you!!

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