Troubleshooting Tips

First steps

Pretty much any issue you encounter will ultimately be explained by a missing solder joint, an unwanted solder bridge (especially between fine pitch pins), or a part that's in the wrong orientation. So spend time checking over all the parts and making sure they're in the right way (if they are polarized, there will be a pin 1 indicator on the board, usually a small triangle on the silkscreen) and check all solder joints. Even if a joint doesn't look problematic, it could have a hidden bridge or a hidden missing connection, so reflowing joints with lots of flux is usually a good idea.

My game does not allow the Game Boy to turn on at all (no power LED)

This means there is a short circuit caused by the cartridge.

Try taking the cartridge out and putting it back in. I mention in the repositories that sometimes the cart edge can become misaligned, and the tabs on the sides of the PCB are there to prevent that, but the issue can still happen occasionally especially with aftermarket shells.

If this does not fix the issue, then refer to the first step. You likely have a solder bridge or a part in the wrong orientation.

My game shows a black bar instead of the "Nintendo" logo on the start-up screen

You likely have not programmed your cart correctly. Try reprogramming it.

My game shows a garbled "Nintendo" logo on the start-up screen

Your cartridge connector inside your Game Boy may be dirty. Try the cartridge on another Game Boy if possible, or try another game in your Game Boy. You can also try taking the game out and putting it back in (do not blow on the cartridge).

If this is not the case, and before you go cleaning the cart edge, refer to the first step. You may also have programmed it incorrectly, or with a corrupt ROM file.

My game won't hold a save

If they're on your board, check to make sure you have the switches/jumpers in the correct position to get your game the correct amount of RAM space.

Check your coin cell battery voltage - it should read 3V or higher if it's fully charged. Sometimes, off-brand coin cell batteries will arrive nearly or completely dead. This has been the case for me in the past. I recommend only buying new parts from reputable sellers to reduce headaches.

Also check the current coming out of the battery by measuring the voltage across the battery-series resistor.

The current coming out of my battery is high AND/OR the voltage on the SRAM is measuring very low

As with the previous issue, make sure the save battery actually has a proper voltage and isn't actually dead.

Next thing is to make sure you've powered on your cartridge at least once. This can be done in a Game Boy, or in a cart programmer. The battery management IC may need to be initialized by applying main power at least once.

If this does not fix it, then go back and check to make sure everything is soldered properly and in the correct orientation, and are the proper values.