What is it?
This is a "Hi-Fi" Class D amplifier for Gameboy Color internal speaker.
How it started
I've got GBC and found rusted speaker with crackling noisy sound and it was barely hearable. Headphones is not the way out.
So I searched my parts bin for some tiny amp ic and found TI's Class D mono amp. Exactly what I need. I quickly designed and made small pcb to test it out with some random phone loud speaker. Sound was great and loud. You can read the full story at avrnoob.com
New in version 2
For the next version I selected other Class D amp from Analog Devices, it's even smaller. I pick smaller one so I can make pcb which fits in the speaker cutout in GBC, just on top of the speaker.
New in version 2s
In this one I used TI Class D amplifier ic again. Also mixing stereo signal to the speaker.
Benefits by using it
Main benefit is the sound volume, it's much louder than integrated amp, and takes no space inside.
Class D amp is very power efficient, this means longer battery life, significantly longer.
If you add additional capacitor on the power line you can get cleaner sound than stock (using line out connection). But with GBAmp 2s version you probably not need for additional capacitor, there are plenty fit on the pcb.
How to mod your GBC
You need basic soldering skills to solder 7 wires.
I will provide detailed step by step tutorial.
Open Source Hardware
GBAmp2s pcb is an Open Source Hardware.
Design available for free at: code.avrnoob.com/gbamp2s
Order Now at Tindie.com
Also available at kitsch-bent.com
WARNING If you connect PCB polarity wrong you will fry the amplifier IC, so be carefull.
Tools you need
1. First of all verify that you get the full kit. It should iclude:
2. Unscrew and open your Gameboy Color. Do not forget to remove batteries when you open the case.
3. Take out the speaker and desolder wires from the Gameboy PCB pads shown:
4. Take red wire from the speaker and solder it wire to S+ pad on GBAmp2s pcb. Then take black wire and solder it to S- pad. Solder wires from the back of pcb because speaker will go under GBAmp2s pcb.
5. Take 3 color wires which should be soldered to L, R and GND (unmarked pad) pads.
6. Put wires around so the case can close freely, take a look at finished unit:
7. Solder these 3 wires to the volume ptentiometer according to next picture. If you received presoldered wires, then GND = Brown or Purple or Black color wire. Does not matter which wire you use for L or R
8. Solder the rest 2 wires to the power pins, check GBAmp pcb for V+ and V- silkcreen. If you received presoldered wires, then V+ = probably Yellow color. Please double check GBamp pcb silkscreen.
10. Put speaker in the speaker cutout and push pcb over it.
12. Install back cover. Make sure V+ and V- connected corrctly before turning it on. Enjoy your new sound.
Optional. If you need GBC to switch off speaker when you plug in headphones jack, then you need to connect 3 wires (GND, L, R) to another place. There will be more speaker noise if you use this connection though, due to LCD noise coupling to gameboy amp chip. See next picture for details.
If you want to install GBAmp mod pcb into DMG-001 classic console, then solder wires as shown on the next pictures.
Desolder original wires from the speaker and DMG pcb first.
If you have a little distorted but loud sound on not max volume settings then swap speaker wires.
If you have the same after swapping, then probably volume control is rusty.
If you do not have sound check all connections and wires.
If you have very low volume and heavy distorted sound then amp is probably dead. Or speaker is dead, check with another speaker.
GBAmp pcb pinout: