Parts required:
[1] EPROM programmer
[2] 3.8mm Gamebit
[3] Soldering iron
[4] 49f040 or similar Flash Chip - PLCC style
[5] ROM image
[6] 30 Gauge wire
[7] Donor Cartridge
Notes: Before choosing a donor cartridge to gut, you must first understand that the GameGear frequently used proprietary ROM chips that had custom mappers built in! What that means is that a donor which may have held a game of 128KBs, 322KBs, etc., is only going to be able to hold a 64KB ROM once you slap a flash chip in it. There is however a solution to this troubling news; you must locate a donor cartridge that had a separate mapper chip. The list is very short, but here they are:
Download Links:
Links are hidden from guests. Please register to be able to view these links.
Alternatively you may locate a mapper chip from inside a Master System cartridge, but they are in the DIP package so they are very large compared to the SMT chips found in the few GameGear carts. I also do not know which carts you can find these in. They will most likely be found in larger games, so have a look at the complete ROM-sets for sizes.
Step 0.
DIY:
If you think you can skip my step by step tutorial, here is the final schematic. Have at it.
Otherwise, move to Step 1.
Step 1.
Program your Flash chip:
Place the chip in your programmer and always check for empty before programming.
If it is used, erase it.
Once empty, load your ROM file and press program.
Step 2.
Prepare the chip:
For the chip to comfortably fit on the board and for the shell to close, you will have to bend and cut the pins. This is a difficult process and too many bends will break off the pins. First, bend the top and bottom pins straight out using a razor and needle nose pliers. Then, bend the side pins up only partially and then straighten them with your pliers. Next, bend the same pins against the chip and out, as shown in the picture below. Cutting them at an angle like in the photo may also help.
Step 3.
Locate a donor cartridge.
If you want to put a game that saves on it, then you need to find a donor cartridge with a save battery. 49f040 flash chips can hold ROMs up to 512KBs but the limit of pcb's without mapper chips is a sad 64KBs. I will soon do a tutorial on pcb's with mapper chips.
Step 4.
Cartridge PCB revealed:
Open the cartridge with your 3.8mm gamebit.
Step 5.
Donor Cart prepared:
Carefully remove the Mask rom by cutting the pins with a razor. Then slide your soldering iron across the board to smooth out the pads you cut from and to remove bits of the pins that were left behind. If there is a mapper chip, do not remove it. These may be labeled "315-5912."
Step 6.
Wires Placed:
Now, place the wires to the pads that do not make direct contact with the flash chip.
Step 7.
Flash ROM Placed:
Line up the Flash Rom as carefully as possible. The chip will not be perfectly straight because of the pin placement, so before soldering, check it again!
My parallel cable has been misplaced while moving out for the summer, so I cannot program any chips until I find it. I obviously do not want to bend the pins with them un-programmed. Step 10 will remedy this setback once I finish it.
pic coming soon.
Step 8.
Wires Attached:
Now, curl the wires toward the chip and attach them one-by-one to their appropriate locations. Refer to the schematic at the top of the post. Be careful!
pic coming soon.
Step 9.
Finished:
[Close up your cartridge and test it out in your Sega Game Gear.