With a few simple modifications, you can convert your standard GBA SP from a regular, front-lit AGS-001 to a Backlit AGS-101. Also, a benefit of the modification is the backlit screen is actually slightly brighter than a stock AGS-101.
So, how do you modify a Game Boy Advance SP to have a backlit screen? To modify your AGS 001 to a backlit AGS 101 we need to cut a trace on the motherboard and connect a 12v regulator.
How to Convert GBA SP AGS-001 to AGS-101
Accessing the motherboard
Accessing the motherboard on a Game Boy Advance SP is quite easy. To gain access, you will need a Tri-wing screwdriver and a Philips head screwdriver.
I’ve actually written a more in-depth guide into reshelling the GBA SP for those who are interested where I got a little more into detail about the disassembly.
With the GBA SP sticker side up, use your Philips head screwdriver to remove the battery compartment and set it aside along with the battery itself (The battery just lifts up). Next, we will need to remove the 6 x Tri-wing screws around the edge of the console. One of the screws is slightly hidden in the battery compartment. Keep a note of where all the screws come from as two of them are slightly shorter then the other 4.
With the screws all out, we can now lift off the back of the housing and set aside. At this point, you may dislodge the volume slider or power switch, if you do set them aside and you can reattach before putting the housing back together.
With the motherboard exposed, we will be removing the 3 x Philips head screws holding down the board.
Please note, If your motherboard is a type C/AGS-CPU-01 like my original below then this mod cannot be performed! (Well, not easily at least for reasons I will get on to shortly!). Luckily, I have a lot of spares and all other motherboards do work. CPU-10 & CPU-11 seem the most common. With this, I switched to my AGS-CPU-10 board.
Gently lifting up the motherboard will expose the ribbon cable. We need to pull down on the brown tabs either side of the brown ribbon cable keeping it locked into place. This will allow us to remove the cable and free the motherboard.
With the motherboard free, we can now find the 1st area we need to modify. We need to cut the trace from the 1st pin of the display connector. This is the reason we cannot use the CPU-01 boards as the trace is actually underneath the connector.
Use a craft knife to cut the trace as pictured below.
This is our voltage regulator. I’ve opted to use the Pololu 12V Step-Up voltage regulator as this is the smallest I have found and very inexpensive.
We will be connecting the wires from the motherboard to the regulator.
The first wire we need to solder is from the 1st pin of the display connector. Fix the wire to pin one and feed the wire through the hole on the motherboard near VR23 and flip over the board as pictured below.
Next, we will be solder a wire to the pad just above the CPU as pictured below. Make sure not to bridge any of the pins of the CPU.
*Be careful when soldering your wire, especially above the CPU. It would be very easy to accidentally slip & remove some of the surface mounted components like the capacitor at C54*
Locate C1 on the power switch and solder a wire to it. make sure the wire has enough length to reach across the board.
With the wiring to the motherboard finished we will now move onto soldering the voltage regulator in place.
The 1st wire from the display pin will be soldered to VOUT
The 2nd wire from the pad above the CPU will be soldered to GND
Lastly, the 3rd wire from C1 will be soldered to VIN
Once connected, I recommend wrapping the regulator in some electrical tape to stop anything shorting when everything is reassembled.