Nintendo Game Boy Color

The Nintendo Game Boy Color is the second revision of the Game Boy Pocket released in 1998, following the Game Boy Light. It features a smaller but fully-colored screen, a faster CPU and more RAM. To open a Game Boy Color, both a triwing and a phillips screwdriver are needed. To open a game cartridge, a Gamebit screwdriver is needed.

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Gameboy Color CGB-CPU-02 motherboard front

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Gameboy Color CGB-CPU-02 motherboard back

Problems and solutions

Problem	Solution
Console doesn't power on	There's multiple reasons why the console may not turn on. One of them is that the power switch may be corroded or dirty. This requires thoroughly cleaning the internal switch with isopropyl alcohol. If this doesn't solve it, probably the F1 fuse over the headphone jack needs replacement. This is a 1000mA 84Ω fuse. If the fuse is fine, then check for continuity between the F1 fuse and the power switch. If there's none, then the via that connects both is damaged. You need to solder a jumper wire between both to solve this. Check video below for reference.
Saved games are being deleted	This could have 2 causes: either the coin battery inside the cartridge (providing energy to the SRAM chip) has died and needs to be replaced, or the C32 capacitor connected to DC-DC converter board is faulty or dead. To repair either: If the cartridge's internal battery is dead, the cartridge needs to be opened with a Gamebit screwdriver. Then, the battery needs to be removed and replaced with an equivalent coin battery (often times a CR2025). Any compatible battery will do if you keep the original battery leads in the cartridge. If your replacement battery has its leads attached to it already, you can solder them into the board. See video below for reference. If the C32 capacitor is dead, it needs to be replaced with a 100μF 6V. Also see video below for reference. To determine which is the cause of the problem, you can try booting up a game, saving, and then turning the console off, and removing the cartridge. Try inserting the cartridge into another compatible system (if you have one, if not, try reinserting the game into the Gameboy Color), and see if the save file was created. If it wasn't, the cartridge needs to be opened and have its battery replaced. If the game did create a save file, it means the capacitors are faulty. Often times, faulty capacitors will cause the Nintendo logo at boot appear corrupted in the same manner when there's dirt in the cartridge slot. This is, however, unrelated, as it means the cartridge is unable to pull the 5 volts it needs to operate, and the console is attempting to pull battery power from the cartridge itself, causing the game to fail to boot and erasing the contents of SRAM in the process. This issue can also manifest in the logo showing up correctly, but then the console crashing to a white screen.
The console has no sound	Check continuity between pins 4 and 5 on the 3.5mm jack. When headphones aren't plugged in, these 2 pins should be connected. When the headphones are plugged in, it breaks the connection so the sound doesn't travel to the speakers. If there is no connection when headphones aren't plugged in, the 3.5mm jack may be corroded or broken. You can try cleaning it with IPA. If the 3.5mm jack works, check to see if audio plays through the headphones. If there is audio playing through the headphones, then the speaker most likely needs to be replaced. If the speaker is quiet on max volume, the speaker most likely needs to be replaced. If there is no sound in the headphones either, it means the C38 capacitor is dead. A 100μF 4V capacitor is needed to replace this. See the videos below for reference. If none of these work, try checking if the audio controller is shorted. The audio controller is right above the cartridge slot, labeled "AMP MGB IR3R53N" (if the motherboard is model CGB-CPU-02), or "AMP MGB IR3R56N" (in every other model). Pins 1, 2, 9, 10, 11 and 18 are ground pins, so these will be read as bridged by a multimeter. This is normal. If any other pins are bridged, try cleaning them with IPA and a Q-Tip. If nothing changes, the audio controller is probably damaged and needs to be replaced. This audio controller has been reverse-engineered by Ken Shirriff, and it's open source. Links for a store that manufactures these audio controllers can be found in the "replacement parts" section below.
Buttons don't work	Button test points The most common fix is to clean the contacts on the board and the rubber button pads with IPA. If this doesn't work, connect the button contact to ground with a tweezer to see if it presses the button. If it does, then the rubber button pad is dirty or defective. If it doesn't, check to see with a multimeter if the button contact has continuity to ground. If it does, then something on that line is connecting that trace to ground. Visually inspect the traces, test points, and vias for any corrosion or excess solder potentially connecting that line to ground. If it's not, then the trace is most likely broken somewhere on that line. Visually inspect the traces, test points, and vias for any signs of corrosion or damage. Test with a multimeter to make sure the traces are making a good connection. If there is a break in the line, repair it with a jumper wire. If a via is corroded, run the jumper wire through the hole to the other side of the board to fix the connection. See photo for reference.

Identifying damaged components

Sometimes (not always), it's possible to detect if a capacitor needs replacement by looking at it. The capacitors in the board don't tend to swell enough to be recognizable to the naked eye, but it's still enough for a small crack in the paint to appear. See example:

The black portion (corresponding to the negative side of the capacitor) should be uniform like in C35 to the left, but it has a silvery crack across it, meaning the capacitor has swollen.

Usually, if there is rust in the speaker, it's a sign that this capacitor needs to be replaced. See pictures for examples:

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Repair videos

Troubleshooting power issues and soldering jumper wire

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Troubleshooting audio problems and replacing capacitors

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Replacing speaker

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Replacing game cartridge battery

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Replacement parts

Part	Store link
Audio controller	IR3R56N