Okay, first I take no responsibility for you hurting yourself or others or destroying your game. YOU DO THIS PROJECT AT YOUR OWN RISK!!!! This is what I know to be easy for someone who has little knowledge but it does involve tools and heat and/or flame so BE CAREFUL!!!!! and work in a fire safe environment on a table or work bench and do not wear loose clothing and clear any paper products and anything flammable from your working area. It is a good idea to wear goggles as well to protect your eyes just in case. Finally, read these instructions in totality and carefully before starting the project. If you have any questions or need clarification, ask me! Alright, here is what you have to do:
Step 1:
If it is a Genesis cart and you have no gamebit to open it with, here is a little trick to make a homemade screwdriver. Buy some of those really cheap (only a couple cents each) clear plastic Bic pens that have only three parts to them: the outer shaft, stopper, and ink/roller ball. Here is what I'm talking about:
www.bicworld.com/inter_en/bdd/product_writing.asp?product_id=41Alright, now you have to take out the stopper and ink/roller ball so that you only have the clear plastic shaft. Alright now heat with a lighter around the hole of the outer shaft that used to lead to the roller ball until it melts a tiny bit. DO NOT BURN IT! Just heat it until you can easily shape the plastic. Now while the plastic is still pliable, put the pliable shell hole to the head of one of the screws and let it cool. Once a couple minutes have passed, pull the pen shaft off of the screw and it should have taken the shape of the screw head. Make sure that the pen shaft is completely cool and intact. Congratulations you now have your own homemade gamebit! Now try to unscrew the two screws on the back. If your pen shaft breaks or becomes stripped, try the process again. The beauty of this trick is that it is so cheap and quick so you can restart!
Warning: resist the temptation for sexual jokes in this past Step.....hehe shaft....hehe shaft hole....dammit!
I got this idea from here if you need a better description and pics:
www.mmmonkey.co.uk/console/other/diy-gamebit.htmStep 2:
Once you have the screws out it is easy to open a Genesis game. Just separate the two plastic halves. Alright, you should see the circuit board now. This can be mystifying if you've never seen the insides of a cart before but don't panic! You can ignore everything on this circuit board except the battery. Here is how to identify it. If you've ever seen a watch battery or Dreamcast VMU battery you know what this looks like. It is a circular metal disc about the size of nickel and is probably the biggest object connected to the board. Take note of which contacts are touching the positive and negative sides. The side with the writing is the positive side and the side without writing is negative. Alright, you know what the battery is now. It should have a metal contact strip on the top that you can see and a contact on the bottom that you can't see. It should also have a 4-digit battery number (usually CR2032 but it may vary depending on the system) on the positive side. Copy this down because you will need it so you can buy a new one to replace it with. They can usually be found at drug stores, jewelery stores, and grocery stores without too much problem.
Step 3:
This Step is the hardest. Alright, you need to separate the battery and the contacts. Remove the top one first. Alright, you can try to do this without a soldering iron but it is not recommended but you can try to pry the contact off with a really thin, small bladed flathead screwdriver. Now this is difficult to do without the heat from the iron because you risk breaking the contact if you are not patient, slow, and precise. It is okay to bend the contact but if you break it the cart is pretty much dead so just throw it out at this point. If you do have a soldering iron, heat the contact a LITTLE as well as the area on the battery around the contact. DO NOT HEAT THE BATTERY OTHER THAN TINY BIT OR YOU COULD EXPLODE THE BATTERY AND HURT YOURSELF!! PLEASE KNOW WHAT YOU ARE DOING!!! The idea is to just loosen the factory solder on the battery just enough to loosen it so you can pry the contact off the battery. Alright once this is done, bend the bottom contact away from where it leads so you can get a good look at it. Repeat what you did with the first contact. Now you should have the battery in hand and a circuit board that has to contacts that have nothing in-between.
Step 4:
Alright, now take your new battery out. Make sure you know which side/polarity of the battery goes with which contact. If you are new at soldering and wish to solder the battery for a more permanent connection, here is a few tips. When soldering this battery you are going to have to use a small gauge solder for ease of use. Make sure the iron is heated up before starting. You want to first do the bottom contact and its respective battery side. Make sure the When soldering two pieces of metal (in this case the bottom contact and the battery) you need to first heat the part of the metal on each piece that will get solder on it. This will help the solder bind to the material better. REMEMBER DO NOT HEAT THE BATTERY MORE THAN A COUPLE SECONDS!!!!! Alright, now heat the very tip of the solder wire. You may want to heat this first over a piece of wood to see how much drips off and how it drips off so you can get a feel for how to deal with melted solder. Okay, you need to do this swiftly so both the contact and the battery do not cool but do not rush because you can always reheat the metal. Put a tiny drop of solder towards the end of the top of the bottom contact and place the battery's corresponding side on the solder before it solidifies. THIS IS IMPORTANT!!! DO NOT MISS THE CONTACT WHEN SOLDERING OR YOU COLD HAVE SOLDER DROP ONTO THE CIRCUIT BOARD AND DO DAMAGE TO YOUR GAME!!!! YOU ONLY NEED A TINY DROP!!!!! Now, let the solder cool for a couple of minutes. When you come back the battery should be fused to the contact firmly. Now bend the battery and bottom contact to the position you found the contact and its original battery when you first opened the cart if you have not already done so. Now you are going to do the same thing with the other side of the battery and the top contact but you are going to apply the solder to the battery instead of the contact. Alright now let it sit to cool. The battery should be firmly attached to both contacts now.
Alternate Step 4:
If you don't like soldering here is another option. Take an inch-long strip of Scotch or electrical tape. Take one of the ends of the tape and stick it to the bottom the bottom contact with the sticky side up. Make sure to leave a little bit more of the end of the tape on the contact so that there is tape hanging off 3 sides of the contact (the fourth side is going to lead down to the circuit board). You also want most of the tape still hanging off not being stuck to anything. Basically you want enough tape to "blanket" the contact so that the tape will have enough sticky area on it. Now, take your battery and stick its respective side/polarity to that same end of the tape so that the contact and the battery are connecting and are held together by the tape. Bend the battery and contact (with one end of tape still hanging off) back to where you found the original battery and bottom contact if you have not already done so. Now take the other end of tape and wrap it around to the top of the battery and attach the battery to the top contact using the same method as the bottom one. Make sure that there is no tape in-between the contacts and the battery as you want them to connect and make an electrical current. Now you have successfully attached your contacts to the battery with a mere single piece of tape!!! This should hold for a very, very long time if you taped everything securely. It should hold at least until you need a new battery.
Step 5:
Put circuit board back in the plastic housing the way you found it. Do not put the screws back in yet. Test the cart first by creating a save file and save at a checkpoint/ beat a level. Now turn off your system (not reset) and turn it back on after a couple seconds.
If your save file is still there: Congratulations! You have successfully changed your cartridge battery!!! Put your screws back in by hand so you do not strip them and tighten them with your pen shaft (hehe....shaft).
If your save file is not there: open the cart again and take a look to see where the battery and contacts are not connecting correctly.
If you soldered: make sure you didn't use too much solder to make the connection. You should have only used a tiny drop. If the soldering is botched (ie not straight or making a good connection or wrong polarities are touching the wrong contacts) you are going to have to undo your solder by heating and prying as in Step 3. If it is messed up beyond remedy I am sorry for your dearly departed game but I warned you of the risk.
If you taped: just re-tape as described in Alternate Step 4. The good thing about this is that the process is easy to fix, fast, and cheap though not as permanent and secure as soldering. Just makes sure the polarities of the battery are touching the correct contact and make sure they have a good connection.
Alright, I'll make alterations to these instructions as needed if you guys have any problems. Some of what I had to so is hard to describe without pics but I don't have my carts with me to show you so I may revise how I describe some steps. Ask for clarification as needed. Do not try before making sure and DO MAKE SURE TO HEED MY WARNINGS AT THE BEGINNING OF THE INSTRUCTIONS AS THEY ARE VERY IMPORTANT AND I DO NOT WANT HARD FEELINGS OR HURT FRIENDS ON MY HANDS. BE SAFE AND LEARN IN THE PROCESS.