Getting Started with Homebrew on Xbox 360

[littlestevie360]

there's no resistors to be used anymore in the JTAG part for any motherboard type.. just read the tutorial kk

those are the OLD xenon points.. which uses 330 ohm resistors. these are the NEW Xenon points...

if im running the old xenon points with the 330 ohm resistors is there any point in updating to the new method? i havent been following the change, just personally i dont want to change it if i dont have to

[jelle2503]

i guess both methods work.. but the newer must be the better, or else there would've been no point in releasing this new schematic for Xenon right ?

[Arakon]

the diode way is theoretically safer than the resistors. I've had no issues with the resistors, though.

[littlestevie360]

the diode way is theoretically safer than the resistors. I've had no issues with the resistors, though.

this is what im meaning :/ i grew up with the saying, if it aint broke dont fix, now if there is something wrong that we will see occurring in the future (such as blowing the GPU) then i want to prevent that from happening, if its nothing more than just a new method and a theoretical safety i dont see much point in changing,

[Blackaddr]

The issue is the fact that you are driving a 1.8V GPU I/O with 3.3V signalling from the SMC. 

The resistors in the original hack work as current limiters, they do not shift the voltage.  The idea is that the current limit prevents you from providing enough current to damage the GPU.  The problem here is that damage can be cumulative, you are driving the GPU EVERY time you boot the console, so one day the I/O could start getting flaky on the GPU and once that happens your will not be able to boot homebrew reliably anymore.

The new connections using diodes onlym make use of external pullups to 1.8V on the board to convert the signals to open-drain.  This means when the SMC drives a 3.3V logic high, the diode disconnects the line and the GPU sees 1.8V from the pullup.  When the SMC drives low, the diode turns on and the GPU see's 0V which is safe.

In summary, the diode method is 100% safe and the correct way to do this.

The resistor method *should* protect you because the current should never reach a high enough point to damage the GPU I/O.

It's really a personal choice whether you want to go to the effort or not to be guaranteed safe, or just very likely safe.

[Appl3Kork]

Thanks for this!  Be something to read up on so I can become familiar with it!

[littlestevie360]

The issue is the fact that you are driving a 1.8V GPU I/O with 3.3V signalling from the SMC. 

The resistors in the original hack work as current limiters, they do not shift the voltage.  The idea is that the current limit prevents you from providing enough current to damage the GPU.  The problem here is that damage can be cumulative, you are driving the GPU EVERY time you boot the console, so one day the I/O could start getting flaky on the GPU and once that happens your will not be able to boot homebrew reliably anymore.

The new connections using diodes onlym make use of external pullups to 1.8V on the board to convert the signals to open-drain.  This means when the SMC drives a 3.3V logic high, the diode disconnects the line and the GPU sees 1.8V from the pullup.  When the SMC drives low, the diode turns on and the GPU see's 0V which is safe.

In summary, the diode method is 100% safe and the correct way to do this.

The resistor method *should* protect you because the current should never reach a high enough point to damage the GPU I/O.

It's really a personal choice whether you want to go to the effort or not to be guaranteed safe, or just very likely safe.

thanks this explains it a bit better, i was under the impression that the current limiting should be enough, i might actually switch to the diode method now that i can see a big difference in how it works

[zillionare]

I didn't install diode's. I've had no problem seeing the right FlashConfig:01198010....So figured my wiring wasn't too bad.

Since I have read these added post....and I can't seem to get a matching dump in total commander. I will try the diode schematic posted here.

I have 1 question.......there's "a jumper going from J2D2-4 to J1F1-5 on another schematic with a 330 ohm resistor" and on this one it has nothing on J1F1-5 but ....J2D2-4 bridges to J2D2-7 with no resistor or diode. So whats the difference? and why the change on that connection?

I'm rebuilding my SPI LPT connector now....just trying to understand the differences and be more safe.

The issue is the fact that you are driving a 1.8V GPU I/O with 3.3V signalling from the SMC. 

The resistors in the original hack work as current limiters, they do not shift the voltage.  The idea is that the current limit prevents you from providing enough current to damage the GPU.  The problem here is that damage can be cumulative, you are driving the GPU EVERY time you boot the console, so one day the I/O could start getting flaky on the GPU and once that happens your will not be able to boot homebrew reliably anymore.

The new connections using diodes onlym make use of external pullups to 1.8V on the board to convert the signals to open-drain.  This means when the SMC drives a 3.3V logic high, the diode disconnects the line and the GPU sees 1.8V from the pullup.  When the SMC drives low, the diode turns on and the GPU see's 0V which is safe.

In summary, the diode method is 100% safe and the correct way to do this.

The resistor method *should* protect you because the current should never reach a high enough point to damage the GPU I/O.

It's really a personal choice whether you want to go to the effort or not to be guaranteed safe, or just very likely safe.

thanks for clearing up the need/change to diodes on the JTAG. Still unclear about the deletion of J1F1-5 being used and jumping from J2D2-4 to J2D2-7 with no resistor or diode.

I'm reading up more before any more dumping. I will use the new(est) diagram from this thread.

again many thanks!

peace, zil

[tommyv]

I didn't install diode's. I've had no problem seeing the right FlashConfig:01198010....So figured my wiring wasn't too bad.

Since I have read these added post....and I can't seem to get a matching dump in total commander. I will try the diode schematic posted here.

I have 1 question.......there's "a jumper going from J2D2-4 to J1F1-5 on another schematic with a 330 ohm resistor" and on this one it has nothing on J1F1-5 but ....J2D2-4 bridges to J2D2-7 with no resistor or diode. So whats the difference? and why the change on that connection?

I'm rebuilding my SPI LPT connector now....just trying to understand the differences and be more safe.

The issue is the fact that you are driving a 1.8V GPU I/O with 3.3V signalling from the SMC. 

The resistors in the original hack work as current limiters, they do not shift the voltage.  The idea is that the current limit prevents you from providing enough current to damage the GPU.  The problem here is that damage can be cumulative, you are driving the GPU EVERY time you boot the console, so one day the I/O could start getting flaky on the GPU and once that happens your will not be able to boot homebrew reliably anymore.

The new connections using diodes onlym make use of external pullups to 1.8V on the board to convert the signals to open-drain.  This means when the SMC drives a 3.3V logic high, the diode disconnects the line and the GPU sees 1.8V from the pullup.  When the SMC drives low, the diode turns on and the GPU see's 0V which is safe.

In summary, the diode method is 100% safe and the correct way to do this.

The resistor method *should* protect you because the current should never reach a high enough point to damage the GPU I/O.

It's really a personal choice whether you want to go to the effort or not to be guaranteed safe, or just very likely safe.

thanks for clearing up the need/change to diodes on the JTAG. Still unclear about the deletion of J1F1-5 being used and jumping from J2D2-4 to J2D2-7 with no resistor or diode.

I'm reading up more before any more dumping. I will use the new(est) diagram from this thread.

again many thanks!

peace, zil

answering your question, (but someone correct me if I'm Wrong) the jumping from J2D2-4 to J2D2-7 is simpy another alternative, some people have been having trouble when they connect  the J2D2-4 to J2D2-7 wire without a diode (red lights and errors) so they also use a diode for connecting these points and get better results, so is best if you use diodes on all three JTAG points.

by "jumper" people mean connecting one point of the mother board to another directly with a  simple wire, right?

[rkkman]

You are correct Tommyv...Just a wire is sufficeint.

[xdanx]

Can this mod be done with 256 and 512 JASPER?

[zillionare]

Thanks guys......got it sorted.

Used the schematic here with 3-diodes. one on LPT and 2 on JTAG. So just used a jumper from 4 to 7.

worked! finally got matching dumps. All 11 of them(8 hours) and worth every minute.

zil

Almost forgot I changed my ground from (J1D2-6 to LPT-18) to (J2B1-12 to LPT-18). alternate point.

[xdanx]

I'm planning on doing this mod tomorrow and so far I have a pretty good understand of the tutorial after reading it several times.  The only part that I don't get is the GND point.

*You must join GND in both devices: PC (LPT pin 18) & XBOX360 (J1D2.6 or J2B1.12 or any other ground point of the motherboard)

Does this mean I have to use both J1D2.6 plus J2B1.12 and connect it to LPT pin 18?

[MotoMax]

No just use one that you like.  What ever easier to solder. You only need one ground point. 

[Blackaddr]

Personally, I grounded to the large copper ring surrounding the screw hole for the DVD rear leg.  This is one instance when you want the iron HOT!  Heat up the outer part of the copper ring so it's hot enough you can flow a nice blob of solder on it, then solder  the ground wire to the blob.  This allows for one less wire you have to solder to small vias, no risk of actually solder bridging something you didn't want to touch, etc.  Getting solder to flow onto the copper ring can take a lot of heat because it's connected to the ground plane which is a giant heat sink.

The reason  you do this on the outer edge of the ring is to leave room for the DVD plastic leg to sit flush on it still.  If your solder gets in teh way and your DVD is a little skewed, just grab a file and file down a little bit of the plastic leg to remove the interference.

[Blackaddr]

Regarding the jumper wire, maybe someone can clear this up.

We are using the SMC to drive some GPU JTAG pins.  Two of them get level shifted, one of them is tied off.

I'm assuming the two level shifted ones are TMS and TDI.  I assumed the one that is tied off is nTRST but it could also be TCLK if the GPU JTAG doesn't have a constant test clock.  TDO obviously would not be needed for the exploit.

- Blackaddr

[Senorchris]

I've got a couple of newbie soldering questions, if anyone wouldn't mind sparing the time to answer them.  I've successfully made the modified LPT cable, and am going to attempt to solder it onto the board tonight.  The box is a Xenon, if it makes any difference.

1) When soldering the JTAG hack, is it best to solder the diode to two pieces of kynar (30 awg) wire, and then solder the wires to the points on the board, or to go with only one piece of wire, and solder the diode directly to one of the points?
2) I've noticed there are two types of points that I'll need to solder to (on the Xenon board) - pads that look like they have a blob of solder in the middle already (from the factory), and pads with a hole in the middle.  Is there a tried and trusted method for soldering wires to each of these pads?  Here's what I plan to do:

i) use cotton swab to cover pad with flux
ii) tin pad (possibly using a bit more solder for the pads with a hole in the middle?)
iii) tin wire
iv) rest wire on pad - heat both pad and wire with soldering iron (have a 30w iron - 3-4 seconds of heating?) - apply solder to joint

Thanks to anyone who can give me points/tips - I've soldered before, but never on anything I give much of a damn about breaking. 

[dangal]

Thanks for your time!!!!

[lithium210]

Just signed up on xboxhacker. great site btw!  I never updated my 360, its below 7371 so i'm deciding to try out this modification. Question though.. is it recommended on a falcon motherboard to have a 330ohm resistor on points  j2d2.4 & j2d2.7?? Read about people getting 3rrod error when not using any resistor. Also confused on the tutorial "In the diagram above, I do not require the diode on LPT pin 11, diode is used to get correct flashconfig in Nandpro)" so does that mean i should/shouldnt add a diode to that location??

[Uloga]

Thanks, this is what I needed