Hey there, guys. I have a copy of Sonic 3 made by Tec Toy (Brazil) that I got back when the game was first released, and it was never able to retain game saves. I didn't think much of that back in the day, I just assumed that saves were meant to be used during a single play session and were not supposed to survive a power cycle. Several years went by and after reading online that the game was actually supposed to keep saved games indefinitely, I decided to investigate. Once I opened the cartridge, I immediately noticed that a trace on the back of the board appeared to have been intentionally destroyed (the big red arrow is pointing to it): I didn't do anything about it at the time, and now several more years have gone by and I decided to try and fix it. I could just fix that trace and see what happens, but I'm kinda afraid to do it, since it appears that someone who knew what they were doing intentionally cut it, and they must have done it for a reason. I'm pretty sure we got the game new from the store, and I have no idea why Tec Toy would sell a cartridge like this. So before I try anything, I'd like to at least make sure that this is related to the save feature and could indeed be the responsible for saves not working. Following that trace back trough the hole to the front of the board, under the capacitors all the way to the edge connector, it looks like it's the /LWR signal (Write enable for lower byte of a word), which sounds like something you'd want to prevent going to the FRAM chip if your intention was to disable saving, but I can't really see if the other end of the trace really goes to the FRAM chip and to which pin, since it goes under some chips and I can't find my multimeter anywhere right now. Does anyone here have any advice regarding this? Is the wiring of Sonic 3 documented somewhere that I could check and see what the rest of the circuit is like? Do you have any idea why anyone would want to intentionally disable saves before selling a brand new Sonic 3 cartridge? Do you think it's safe for me just to fix the trace or could the board have a serious manufacturing flaw that restoring that trace could fry something? Thank you very much any information you might have! EDIT: Found my multimeter and the trace does indeed go to the FRAM's /WE pin, so fixing the connection should make the FRAM writable again. I might give this a try, but I can't get over how weird it is that someone would deliberately damage this trace at the factory... Unless this was actually an accident, maybe the board was in the wrong place when they were shutting the case and the screw did this to the board? I don't know, doesn't seem likely.
If anyone is curious, I did fix the broken connection and the cartridge finally started saving games, almost 30 years after it was manufactured! I initially intended to work only around the damaged area, but the solder points are too close to the hole where the screw goes, and anything I placed there would certainly prevent the plastic shell from closing property, so instead I connected a wire directly to the correct pin in the FRAM chip. I still can't get over how weird it is that a cartridge would come out of the factory damaged like that, specially if that was done on purpose, but it's cool to finally have a fully working cartridge after all this time!
This makes me wonder if there's anyone else on the forums that have the same version of Sonic 3 as you and have the same issue... I'm guessing not since no one has replied to your thread until now. That's quite odd, what was the point in destroying the trace? That's quite a huge mistake to be made, perhaps quality control didn't do a good job the day your cartridge was manufactured.
I'd definitely be interested in taking a look at other Tec Toy Sonic 3 cartridges if anyone here has any. I'm very much inclined to believe this is an isolated case... It'd be very weird if some worker at Tec Toy's factory was crushing PCB traces on purpose.
