First off, there are a few tutorials about making one of these floating around on the internet however, I felt they did no justice at proving what goes where. This is why I decided to tackle this obstacle myself and provide details step-by-step of how this was accomplished.
An XBox eeprom reader can be a very useful tool to keep handy. With your eeprom you can build a hard drive within your pc and just pop it in your XBox with the correct files to make it boot again or to even throw in an already softmodded configuration. There are many more possibilities and I won't go into detail on all of that, let's get strait into the build!
Tools You'll Need:
1. Wire Strippers
3. Soldering Iron
Step 1: Components You'll Need
1. Female Serial Connector
2. (2) 5volt Zener Diodes
3. (2) 4.7k Ohm Resistors
4. Alligator Clip (Optional)
5. Pin Header (Optional)
6. Electrical Tape
7. Some Wire
Note that these resistors are stackable. What I mean is say you only have half of the required ohms, you may twist two together to get the desired amount. I believe you may use anywhere from 3.9k ohms to 4.7k. I myself have built one of these cables with four (2 twisted together separately) 2.2k ohn resistors without running into any problems. If unsure of the resistance, there's a free app on the Google Play Store called ElectroDroid that will assist you with the resistance according to colored bands for your convenience. The 4.7k ohn resistors I've used here consists of four bands, Yellow, Purple, Red & Gold.
Step 2: Getting Started
Strip your wires on the opposite side of the serial connector. Use a multimeter to find which wire goes to which pin. For this project we will only need pins 4, 5, 6, 7 & 8. It's best to write these wire colors down, don't be a hero! Also, depending on the cord manufacturer, etc. your colors may vary. Keep this in mind. Next cut off excess wires and we're ready to begin the operation.
Step 3: Resistors
We start off by soldering together (in my case) the blue and purple wires and also adding one side of a resistor to it. We'll want to do the same with the yellow wire as well. I wrapped the wires around one leg and began soldering first then cut off the remainder. Next we'll solder the other side of the resistor on the yellow wire to the gray wire without removing the rest of the leg.
Step 4: Diodes
Now we'll get started with the diodes. If you've never used these before you'll notice there is a black line on one side of these things. We'll want this facing upward as we twist the bottom legs together. Do note that we are planning to be stuffing these into a single cord so we will not want to stack them directly side-by-side. Instead, just position one slightly lower than the other and solder them to the green wire. Again with the Black line facing away from the solder point.
Step 5: Our Ground Wire.
Now is probably the best time to get our first wire into place. Below both diodes we'll want to solder our black wire and put some of that trusty electrical tape to use (on the undersides of our resistors as well).
Here is where things start to get interesting- solder the resistor from the yellow & gray to one of the diodes.
Step 6: Moving Right Along..
Between our gray/yellow wires and diode (black line side) we'll now solder our red wire. After this, solder the blue/purple wire to the other diode and connect the green wire between the wires and the black line of the diode. Now we may again snip the excess and tape our exposed points. Congratulations, you may now set down your soldering iron and slide the heat tube up!
Step 7: Wouldn't Wanna Get My Fingah Caught in Thay'uh.
Slice a small amount of heat tube and slide it down over the ground wire before getting started with putting the alligator clip into place. Slide the ground wire up through the clamp and use a flathead screwdriver to lock it into place before sliding the heat tube up over the surface.
Step 8: Final Steps.
Possibly an optional step here would be to grab a pinheader (either off the shelf or out of an old desktop computer) and a razor blade, chop straight down where it bevels so you're left with two pins aligned with plastic. Remove the two pins and solder them separately to the remaining red and green wires then place them back in the plastic.
Step 9: Lastly..
Grab your heat gun and start shrinking some tube! In my build, I felt the red and green wires looked a little chincey so I decided to put some heat tube over those as well, all the way up to the pinheader. When testing it out I found the pins to push themselves out of their sleeves so I eventually added a zip tie directly after them. This also allowed me to visually identify which pin was which being that they were now covered. Now head on over to Lancos, download a copy of PonyProg and get reading/writing!
Step 10: Final Notes.
To set up PonyProg, choose 'Setup' at the top of the screen and 'Interface Setup...'. At this point, choose which COM port has your serial cable attached to it. If you're unsure, (on a Windows OS) right now press the Windows key + R and type devmgmt.msc. In the list should say "Ports (COM & LPT)", the underneath, "Communications Port (COM'#')". After verifying, hit 'ok' in PonyProg and 'Setup' again, "Calibrate" (if it doesn't automatically insist). Now you're ready for your first reading!
The picture provided shows the SDA & SDL locations on the 1.6 LPC however I am unsure of the locations for other versions. To be safe, connect to the pins listed on the eeprom chip itself or do a quick search based on the version you're working with. Note the yellow marker in the picture is to verify where the dot on the eeprom chip is, use this as a guide for all other models.
Before taking a reading you'll first have to understand how to take a reading, of course. First disconnect the DVD-Rom & hard drive from the motherboard. Plug power cable as well as the video cable into the XBox (otherwise you'll be stuck with a solid yellow light). Now power it up and just wait for it to start flashing red. You may now take a reading. Place the prongs onto the pins of the eeprom and hold them there. While still holding them there hit the 'read' button located in the far-left corner of the PonyProg window. It will notify you of success and give a long, strange code of what seems like gibberish. Now file, save as.. Be sure to save it as a .bin then Google 'Liveinfo Beta 3' to read your eeprom easily. That's it! Now you may use this key to repair your XBox, softmod, upgrade to a bigger hard drive, etc.
If you found this guide helpful, please leave a 'thanks' in the comment section. I hope this helped more than the other guides out there on the subject. I'm sure I'd have been more grateful to have this than what I found. Thanks for checking out my guide and if you've yet to try it, good luck! I hope this makes it seem less intimidating as well.