GBC-101 Tutorial

DIFFICULTY: 8 / 10

UPDATE APRIL 2019: When I made the GBC-101 in January of 2017, there was no easy method of having a backlit GBC. This has changed since. BennVenn Electronics designed and created both an adapter ribbon to connect a 101 screen to a GBC board, and later an actual drop-in LCD which fits the GBC case. Therefore, this is no longer a recommended way of building a backlit GBC. If however, you enjoy pain or a challenge, read along :)

Needed:

  • GBA SP 101
  • GBC
  • Micro USB charging board
  • 2000mAh LiPo battery
  • 2 color LED
  • Copper tape
  • Kapton tape
  • 2-side tape
  • Liquid tape
  • Magnet wire (I used AWG 32 [0.2 mm])
  • Epoxy
  • Krazy glue

Optional:

  • Glass screen lens
  • Button set
  • New shell
  • 2-position switch (for the brightness switch)

Tools:

  • Dremel + drill bits
  • Soldering iron
  • Triwing screwdriver
  • File set
  • Craft knife
  • Set of pliers
  • Multimeter

Note on fuses: At some point during your modding adventure, you might find that the 101 suddenly stops turning on. If you had power plugged to the board, chances are something has grounded and a fuse has burnt. There are two fuses on the 101 board. I found that I only always burnt F2, never F1. So you can usually check that one first. If the fuse has burnt, you SHOULD replace it. Bridging it will make the board turn on, but if there is some problem with your wiring, something else might burn on the board, and you don’t want that. In my case I probably burnt the fuse about 6 times. I kept pulling fuses from old SP boards I had laying around (the fuse is the same on all SPs). I understand the GBC also has at least one fuse, so that might also be a good replacement in a pinch (I am not however sure if it has the same current rating as the ones on the SP). In the end though, if you are careful when soldering and always double check that nothing is grounding (with your tester) before turning the power on, you should be fine.

The first step involves opening up the SP and the GBC. Save all screws and loose bits in a bag so you don’t lose them. This is where you will need the triwing screwdriver.

The next step involves trimming the SP board so that we can fit it in the GBC shell. First of all, all unnecessary bits should be unsoldered from the board. This includes the L/R switches, the charging and EXT ports, the battery connector, the volume slider, the power switch, the cart connector and the GBC/GBA switch. On the front side of the board, the LEDs on the right and components EM1 and EM2 can also be removed (these are no longer needed since we will not have the EXT port). Also, the button pads can be removed to expose the contact pads underneath. This can easily be done by scraping away at the film over the little dome until the dome comes free.

Now comes the first of many fun parts: cutting the SP board. This basically involves studying the board to see what can be cut off from every side of it. It’s really just a matter of seeing what is empty space or thick ground traces and thinking about how much would be safe to trim without fully cutting any traces. It is not that difficult if you know what you are looking for. Here’s an image of what I managed to safely trim:

Since I installed the board in the same orientation it had originally, this was enough trimming to get the board to fit. You might notice I chose to cut around the volume solder points: even though I could have trimmed them and tapped somewhere else, I wanted to make soldering a bit easier later on, so instead, I chose to trim the inside of the GBC shell in those two points. As an added bonus, this served as a bit of an anchor for test fitting the board later on.

You might also notice I cut some components belonging to the EXT port. Sadly, I was unable to fit the port in this build, so the port you see in the pictures is just there for aesthetic reasons. Maybe in a future build I will try to also have a working EXT port.

The next step involves trimming the GBC board. This is much, much simpler since all we want it to reuse the button pads. First off, desolder the bits we will be reusing: the headphone jack, volume wheel and power switch. Then, go ahead and cut the board. This cut worked for me:

After trimming the GBC board, you should make it as lean as possible by unsoldering all the bits on the back of it.

At this point it’s time to trim the GBC shell. The parts you will need to trim for sure are everything in the screen area (since the 101 screen goes from end to end of the shell) and the battery compartment. Here’s what my shell looks like after trimming:

I also had to make a notch for the solder points I didn’t trim earlier. You might or might not need to do this based on how much you trimmed off the board.

Some other minor adjustments need to be made to the shell. First off, I needed to cut a piece of the speaker “wall” off, so the SP speaker’s notch could fit. I also had to make the headphone hole a bit deeper, since the headphone port sits a bit lower now than it originally did on the GBC. Finally, a hole needs to be cut for the micro USB port. What I did was to find a drill bit of the same size as the existing DC jack hole, drill a few mm to the side of it, then use a flat file to even out the space between both holes. In this way, a fairly even oval hole can be cut. If measured right, it should be the same size as the micro USB port on the charger.

At this point, it would be wise to attempt a fit test. Try to fit all components into the shell and hold them together with a rubber band. This will give you a good idea of progress, and if anything still needs to be trimmed or not.

After the body modifications are done, its time to start with the electronic ones. To start off, I installed the red and green LEDs, which indicate battery life. For this, I used a 2 color, 1.9v LED (link at the top of the page). I set the screen in its place in the shell (make sure to actually turn it on and set the screen cover on top to ensure its centered) and then I marked the spot where the LED should sit on the screen. I used copper tape to make three traces for ground, green and red, and made the tape go all the way around the screen so I could have some easy solder points on the back of it. Make sure to put Kapton tape under the copper tape so the metallic back does not touch the copper and short it out. With that you will have working battery LEDs.

At this point I decided to fit the screen in place since it will not be moved anymore. I put some two-sided tape on the sides of the screen and fit it in place. Again, make sure to turn it on so you can ensure it’s centered. The screen should stay in place as long as you did a good job of trimming, sanding and evening out the inside of the shell.

Its time to fit the GBC’s volume wheel and power switch. For this, I found the right spot for both by means of trial and error, and once I was happy with the location I fixed them to the back of the screen. To do this, I set a layer of Kapton tape on the back of the screen, and then on top of that I put a strip of copper tape. I then put some solder on the tape, and soldered the components to the tape. I wasn’t sure how good the grip would be, but it turned out to be excellent. Just make sure your Kapton and copper strips go from end to end of the screen for maximum grip.

Now that those components are set in place, its time to start working on the 101 board. To start off, solder the GBC/GBA switch so that it’s permanently closed. That way the board will always work in GBC mode, even with no game in.

Then, time to fit the cart connector in place. I found that the GBC connector was just too big and didn’t fit in with everything else. However, the connector from the SP is just the perfect size. To fit it in place, I used epoxy paste. I set some epoxy on the 101 board, then I put a game cart in the shell’s slot, and put the cart connector in the cart. After ensuring the cart was properly aligned and as far down the slot as possible, I put the 101 board in place so that the epoxy will stick to the connector. I left it like this for a few hours until the epoxy dried (made sure to move the cart a few times though in case some epoxy had gotten on it). In this way, the cart connector is now attached to the 101 board in the right place.

Time to do the same thing with the headphone jack and the charging board. Again, fit them in place, then use epoxy paste to attach them to the 101 board. Before fitting the headphone jack however, I had to sand some of the plastic off so that it would fit. Again, your particular build might be a bit different, so just see what is needed as you go on.

Once you have all those components in place, the last component to fit is the brightness switch. I set this one inside the battery compartment, right next to the LiPo battery. Again, epoxy is your friend. If you’re not planning on having a brightness switch, you can skip this step.

Now for what is arguably the most tedious part of the build: soldering the cart connector. Since the connector is already fixed in its final position, it should be safe to solder all of its lines. Pay close attention to how the connector was oriented before you removed it - I didn’t the first time and soldered ALL LINES BACKWARDS (I was tired and not thinking straight, don’t judge me). So I had to do the work twice. Surprisingly the 101 board survived with minor damage (just blown fuse). But don’t do that, double check and do it right the first time. I used magnet wire for the lines, so that it would take up as little space as possible, especially considering that the lines would all have to cross over each other.

After you have soldered all lines and TRIPLE CHECKED all your connections, as well as made sure there are no shorts, go ahead and test plugging in a cart and turning the power on (for testing you can just solder the battery to the power points on the board, or even better, solder a couple wires to the power points and connect your battery to that, so that you can test whenever needed). If all is well and your games run, saves load and save, etc., then you can cover the wire with liquid tape so that is firmly attached and does not move around. Nothing worse than having a trace lift on the board from one of your wires getting caught on something.

Since we have the soldering iron out, might as well do the headphone jack and charging board. The board I used has two “output” pads, so I soldered from there to the battery contacts on the 101 board. If your charging board doesn’t have those, you can solder directly to the same pads that you will solder the battery to.

Regarding the headphone jack, I spent a long time trying to come up with a way of getting audio out of it without having to sacrifice the speaker. The problem with SPs is that, to get headphone level, stereo sound, you need to ground a particular pin on the sound chip. This however turns the speaker off. When the speaker is on, no audio comes out of the headphone lines. Plugging in the SPs headphone adapter normally does this switch. I was unable to find a way of emulating this with the GBCs headphone jack, since the switch on the SP works as a normally open, and the switch on the GBC jack is normally closed.

What I ended up settling on is using the same speaker line as output for the headphones. Now bear with me for a second. Normally this would be crazy, as a speaker line is amplified and a headphone line isn’t. However, the speaker on the Game Boy is so tiny, this actually works. With the volume wheel about half way, the volume is pleasant and there is no distortion whatsoever. An upside of using the speaker line is that the volume can get pretty loud on the headphones, louder than it normally would be. Of course, if you max out the volume, there will be some distortion, but not so much that it would blow up your headphones or anything. The main downside of this method is that the audio is mono :/ This was the main thing holding me back at first from using this method, but I ended up deciding that it was better than no headphones, and besides, the audio on the speaker is mono and I’m fine with that. So I felt that the benefits outweighed the disadvantages. Of course, you are free to not use this method if this bothers you :)

The wiring for my method is as follows:

Once you have the headphone jack wired in, measure the amount of cable needed for the speaker, and wire it to the front of the board, making sure it will fit in place when everything is put back together.

With this wiring, the speaker circuit is closed when there are no headphones plugged in, and it opens when plugged. The line we are cutting is the ground one, since the ground part of the male plug is what touches the metal part of the switch. That way you will not have any shorts.

I had to use the speaker from the SP since the GBC one was too thick to fit. Also, I understand that they sound better anyways, so I guess that’s another advantage of that.

Its time to start looking at how to work the inputs. To begin with, we need to see how we’re going to tap into the GBC button pads. I don’t particularly like soldering directly to the test points on the GBC board, since they’re very fragile and will break if you tug on the cable just a little too much. So instead, what I did is create “solder pads” of my own. First, I threaded a piece of magnet wire thru a hole near each test point. Then, I put a piece of copper tape on a bit of board without anything on it, and soldered the wire to it. Finally, I pull taut the wire and solder it to the test point. I did this for each input. In this way, I’m still tapping onto the test points but I have a separate spot for soldering the wires going to the 101 board. You can now if you wish install your buttons in place and the rubber pads, and screw the board in. We will not need to move it anymore since we can now solder to the back of it. Finally, using your file or a knife, scrape a bit of the mask off on the back of the board until you reach the copper. This is ground and can be used as the common for all the buttons.

Finally, wire the brightness switch. One end should go to the button pad on the original button, and the other can go to any ground spot you find nearby. If you are not putting in a brightness switch, leave the pads inside the button unsoldered for the lower brightness setting, or bridge them for permanent higher brightness.

Time to start wiring both halves of the project together.

To do this in the proper order, I first soldered wires to all the points on the back of the 101 board. I used three wires for the volume wheel, and three wires for the power switch, as follows:

With those wires nicely soldered and isolated with liquid tape, I proceeded to route them around to the other side of the board. I threaded them through the old screw post hole on the top corner of the board and twisted it around once so that pulling on the wires would not put any pressure on the solder points.

At this point, since there is nothing left to do on the back of the board, I decided to attach it to the back half of the shell. First off, I soldered the battery in. Then, I put some epoxy on the inside of the shell right where it touches the cart connector. I pressed the board in so that the epoxy holds the cart connector and therefore the whole board (on the other end of it, the microUSB port and headphone jack make sure the board sits where we want it). I now inserted a game and made sure everything was aligned properly, and left it sitting for a few hours with the game in until the epoxy dried up. Out 101 board is now permanently attached to the back board! #scary

Now, to work on the front of the 101 board. The things to solder here are the power LEDs and the buttons. For the LEDs, you just tap to the original points where the SPs LEDs used to sit. For the buttons, I removed the domes on each button and soldered directly to the points inside (each button has a contact point going to the CPU and one going to ground, make sure you are connecting to the CPU one, not ground. Use your tester in continuity mode for this, you want the point that is NOT connected to ground. You should know this by now).

And now to solder our wires to the other half. The input lines should be pretty clear, you should have one line between each button on the 101 board and pad on the GBC board, and one wire between the ground spot on the back of the GBC board and any ground spot on the 101.

The LEDs should be simple as well, just connect to the tracks we created with copper tape on the back of the LCD. The power switch and volume wheel should be wired like this:

We are finally done with soldering! Time to test. Cover every exposed bit on the back of the LCD, the inputs board, and the 101 board with Kapton or electrical tape. Double check for any ground leakage (the one that got me was the back of the LCD which was touching one of my wires going to the LEDs, this back plate is grounded through the LCD ribbon so it popped the fuse when I plugged it in). If you are satisfied with how it looks, carefully close both halves together and keep them together with a rubber band.

Go ahead and pop a game in. If it works, pat yourself on the shoulder! You just wasted a few days/weeks/months of your life, but man it feels good. If it doesn’t work, all I can say is go back and check your wiring. If any one particular thing doesn’t work it should be easy to find the problem (for example, if the UP arrow doesn’t work, check your wiring to it and from it, etc.) If the system refuses to turn on, check your power and check the fuse. If it is blown, something is probably grounding somewhere. Just work back little by little and you’ll eventually find it. You’re so close now, don’t give up!

At this point I recommend you keep the system held together with the rubber band for a few days. Play with it, make sure the LED turns red when the battery goes down, charge it, use headphones, and generally test that everything works. This way, if something doesn’t work, you can easily get back inside and fix it.

Once you are 100% positive everything works, its time to close the shell for good. Now, you might be able to put some screw posts somewhere and use that. In my case, I got lazy and wanted it finished, so I just attached both halves together with Krazy glue. I was worried the halves would come apart since I needed to press them together a bit to fully close it, but the Krazy glue has held remarkably well. What I did was, after gluing both halves together, I put some taut pieces of painters tape across them and then wrapped the whole thing tightly with more tape. Left it like that all night, and when I opened it next morning, everything was nice and stuck together. It has held remarkably well since.

Granted, it will be very hard to get back into the system if I ever need to, but I’m hoping that won’t be the case :)

And with this, you have reached the end of the tutorial! I hope by this point you also have a sweet, fully working, GBC-101.

If you have any questions or any section of the walkthrough is not clear enough, feel free to leave a comment below!

A few more pics of the finished product:

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