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[crimpshrine]

From new thread on Xboxhacker, this specific post is from Blackaddr:  

QUOTE

If using the JTAG diodes, there is no electrical risk whatsoever.  The "issue' is the SMC is driving 3.3V while the GPU JTAG is 1.8V.

The way the diodes work is they allow the SMC to drive logic LO, but when the SMC drives logic HI (3.3V) the diode effectively disconnects the SMC and a pullup resistor on the board already will pull the line to 1.8V which is the GPU voltage.

The connection with the jumper is simply tying an active low JTAG reset pin to 1.8V, so reset is not asserted.

This method of JTAG hack is electrically SAFE.

The LPT is a different story.  Your LPT port is +5V, your SMC is 3.3V.  Putting resistors in series helps provide a current limit but can still damage the NAND.  There is a definite risk here (even if a small one).  But since most people access the NAND in this way only a few times, then later updates can be done wtih software tools running on the console, this isn't a big issue.

However, I still DO recommend people only use a buffered, level converting interface if they want to be 100% safe.  I posted a schematic for such a circuit in the Hardware section.  I have seen enough flash chips get fried with just resistors from my satellite experience to know not to do it on an Xbox.  So I never use anything other than an electrically safe circuit, but I'm anal, and to my knowledge NO ONE HAS DEFINITELY FRIED THEIR NAND FROM USING ONLY RESISTORS YET.

But this JTAG Saver above is pure snake oil.

http://www.xboxhacker.org/index.php?topic=14754.msg106388#msg106388

[stuntz0rZ]

can this be applied to an already jtagged system?

[HoRnEyDvL]

QUOTE(stuntz0rZ @ Mar 26 2010, 02:17 PM)

can this be applied to an already jtagged system?

Yes it can

[BlueSlingShot]

My jtagged xenon is on for quite a substantial amount of time and my console was done about 2 months ago and no problems.

Hopefully there won't be any either

[subse7enx]

plaguereign you know April fools is next week and not today.. you are a little to early for the prank  

[scuba156]

This isnt a joke. Its an actual product, that actually does what its made to do.

If you dont like it, then dont use it but its there for people that want the actual protection that this offers.

[keropi]

as more tech-related people already commented on XBH , this is pure poo and offers nothing. pointless to the max. It won't damage anything, will work OK but it will offer NOTHING AT ALL.  

[lost4468]

QUOTE(BlueSlingShot @ Mar 26 2010, 04:09 AM)

My jtagged xenon is on for quite a substantial amount of time and my console was done about 2 months ago and no problems.

Hopefully there won't be any either

OH, there will be believe me, there will be

[thethinker360]

well, rather just use a Cygnos360 V2. that is safe and will not do any damage. The team Cygnos had warned multiple times that the other jtag stuff is not electrically "clean"

[ccfman2004]

QUOTE(thethinker360 @ Mar 26 2010, 03:03 PM)

well, rather just use a Cygnos360 V2. that is safe and will not do any damage. The team Cygnos had warned multiple times that the other jtag stuff is not electrically "clean"

Sure they are not just trying to sell their product by falsely warning people about the JTAG hack.

How is Cygnos360 v2 better than the extremely cheap JTAG hack.  Can it run the hacked Kernel without having to JTAG the console?

[luceri]

maybe it's a problem with specific xbox revisions, i don't know, but I've had no problems and have some fairly crazy stuff going on with my jtag.

Internal 2TB 3.5" HDD modded to be accepted by the 360 as hdd1 via SATA and not USB (HUGE performance increase BTW -- Don't know if anyone ever did a guide for this but games load at least 3-4x faster vs USB HDD and NEVER stagger), 6x 5-12v fan controller powered via molex from under the PSU adapter (connected to it are 3 new fans and the 2 rear fans, including 2x 120mm over gpu/cpu and 1x 40mm aiding in exhaust). I've had this w/ dvd drive and an external USB drive, two memory units, and a usb memory stick. If i'm not drawing insane power, i don't know who the heck is.

This is all on an oldschool launch console -- xenon (hence the cooling mod overhaul). I've got at least ~1000 hours on this console jtagged. I leave it on overnight regularly for FTP. I treat it like a PC and just leave it on at least 12-16hrs a day idle most the time but still powered up since the absurd fan configuration has temps insanely low even at full load; With the low temps i figure no big deal.

Now -- this Jtag Saver -- is this saying the Jtag wires THEMSELVES could overvolt and hurt components? I'm not drawing power from stupid places like most people do, just from the PSU adapter itself before the power is circulated. I think this may be why I have no issues maybe? Or maybe it's a Xenon was more hardcore with this stuff type deal -- i don't know. I just figured I'd share my experience with no issues and an insane schedule.

If someone could answer that question I'd be appreciative. I come from a classical PC modding background and am not the best with electrical things. I hold my own and can get what I want done easily but I still don't fully understand all the in's and out's and exactly what these resistors/transistors are doing beyond a basic concept tbh.

[modrobert]

While it has been interesting to read the whole discussion here I can't help wondering what that invalid .tif file is doing in jtagsaver-v1.0.zip. Does "TIFF exploit" ring any bell (it does in my paranoid brain)?

I've been analyzing the file 'Jtag Saver.tif' in the hex editor, but not sure what to look for, maybe someone with experience of TIFF exploits can have a stab at it.

[ccfman2004]

QUOTE(modrobert @ Mar 26 2010, 08:57 PM)

While it has been interesting to read the whole discussion here I can't help wondering what that invalid .tif file is doing in jtagsaver-v1.0.zip. Does "TIFF exploit" ring any bell (it does in my paranoid brain)?

I've been analyzing the file 'Jtag Saver.tif' in the hex editor, but not sure what to look for, maybe someone with experience of TIFF exploits can have a stab at it.

What invalid .tif file are you talking about.  The one I got from the zip is a picture of a schematic.  Try using a program that can read .TIF picture files.

[modrobert]

QUOTE(ccfman2004 @ Mar 26 2010, 08:05 PM)

What invalid .tif file are you talking about.  The one I got from the zip is a picture of a schematic.  Try using a program that can read .TIF picture files.

If my vague suspicions are correct, that would be like asking someone to click on a virus infected .exe.

[p1nky2oo7]

I'm no expert at electrics, elecronics, soldering etc and I have no clue what is actually going in there electrically, however I was able to JTAG 3 consoles myself (1 Xenon, 1 Falcon and 1 Jasper).

And while all the consoles work there is something strange: both JTAGGED HDMI consoles (Falcon & Jasper) will NOT work with the kind of HDMI equipment I got which is like this:

Console -> HDMI autoswitch -> Onkyo AV Receiver -> TV
they do NOT show any video in this configuration, and display on the Onkyo which shows if it gets a signal is usually flashing ike crazy or getting nothing at all

they DO however work this way:
Console -> Onkyo AV Receiver -> TV
ie if I remove the autoswitch but connect the console directly to the Onkyo they will work fine.

now you will say there is a problem with the autswitch (caused by the autoswitch).

BUT: I am 100% sure that both HDMI consoles DID work fine going through the autoswitch before the JTAG hack was applied. Also I got 2 more HDMI consoles here that have not been JTAGGED (1 Jasper and 1 Zephyr, and yes I do have a lot of boxes here ) and those 2 also DO work just fine using the autoswitch.

So in the end I see only 2 possibilities:

either I fucked up both my HDMI consoles in the very same way so that they do basically work, but somehow not through the HDMI autoswitch anymore OR there actually IS some issue with this JTAG hack which 99% of the people will not see (as most people won't go through 2 other devices before the HDMI reaches the TV).

you can call my soldering skills poor and you'd be right but fucking up 2 consoles in the very same, very special way seems unlikely.

also note that the Falcon console uses the normal JTAG hack and was originally flashed via LPT while the Jasper console is modded using the Cygnos v2 (and has exactly the same symptoms regarding this HDMI issue).