Diagram here

Extending the life expectancy of a modchipped v1.6 xbox

In a v1.6 xbox, one of the data signals on the motherboard (LFRAME) is short circuited to ground to let a modchip boot. This puts a strain on the xbox electronics whenever the modchip is operating. Although the modchips work, the life expectancy of the xbox may be shortened by doing this - much like driving your car around with the engine always running at 6000rpm (the car still goes, but the engine will get warn out much more quickly). A resistor can be used to prevent the problem of installing a modchip, and extend the life of the xbox.


A more detailed description:
The bios on a v1.6 xbox is loaded from the LPC bus, the same bus that the modchip uses. Therefore there will be two different bios (modchip and normal MS bios) both trying to load at the same time onto the same wires. v1.0-1.5 xboxs used separate wires to load the MS bios compared to the modchip and so this wasn’t a problem.

So how do we stop the MS bios from loading onto the wires we want to use for the modchip in a v1.6?
LFRAME is used to signal the start/end of a data transfer on the LPC bus. In v1.3-1.5 xboxs MS removed this signal from the motherboard to make "cheapmod" modchips no longer work - so modchip makers generated this missing signal with some extra electronics on each modchip. On v1.6 xboxs we short out the LFRAME signal on the motherboard so that the bios chip on the motherboard doesn't know it is being sent data (it can't see the start signal) and so it doesn't do anything. The modchips now generate the missing signal themselves, so they see the data correctly and can load up without any problem.

So what is the effect of shorting out LFRAME?
Shorting out a signal causes a higher current to flow than is normal. In v1.0-1.5 xboxs we short out D0. This causes a current to flow during the time the onboard bios is trying to load - which is a maximum of a few hundredths of a second. After this it is disabled so no current flows, and the modchip loads up.

On the v1.6 we are shorting a different signal, LFRAME, which as far as the xbox is concerned is required to load the bios in any circumstance. This causes a problem - the signal does not turn off when the modchip loads like the v1.0-1.5 xboxs do. We have a continuous current flowing whenever the modchip is being used - a current which is coming from a data line driver which is not designed to do this!

For those interested, I measured 62mA and 68mA on two different 1.6 xboxs - to put this into perspective a standard 3.3V 74LV series IC output normally operates at a few mA, and has an absolute maximum rating of 25mA (I am comparing with other generic electronic components as I obviously don't have the actual xbox component datasheets - anyone who is feeling generous feel free to send me a copy :-) Some new modchips, such as the Aladdin XT, have had to add an extra point ‘X’ to try and deal with this high current as the original Aladdin modchips cannot cope.

One fix for this is quite simple, cut the data track on the motherboard and insert a resistor. With the modchip off, the resistor has very little effect on the data line and so the xbox boots normally. With the modchip on, the resistor limits the current to less than 5mA (less than one-tenth of the original value) and so prevents any long term damage occuring to the xbox.


If I have made any errors in this description let me know and I will edit it appropriately.

UPDATE: Modchips which pulse LFRAME and therefore do not suffer from this problem:
Xenium ICE
Duox2
(These results are from posts in this thread - I have not confirmed them)

It appears an earlier post about this has prompted one modchip designer to do something about it, read here.

To my knowledge all other modchips hold D0 (LFRAME) low continuously.
Edit: Xenium ICE does not do this and is therefore this is not a problem

Also, cheapmod installs are not effected by this since the LFRAME track is cut and connected to a switch instead of grounding it.

ok then, os its not somethign i have to worry about then. its just that i install mod chips for people, and i dont want them blowing coz of too much current through an ic.

Edit: Double post

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catdog, do you have a diagram/pic with res. value. thx. this worries me also,

this is an excellent post. I shall certainly be following your advice. Thanks catdog2 it is appreciated.
This should be pinned by one of the mods

Definitely! Everyone, including (and especially) the modchip manufacturers, needs to see this. I will start doing this as well.

Hmm this is interesting, i seem to recall that both Xenium and SmartXX modchips only pulsed the D0 & LFRAME anyway to reduce stress such as this. Will have to see if any of the members from either team will comment on this matter.

Untill then though, do you have a link catdog2 of where we can order some of these needed resistors from online?

I think it's this one...

RS Components : 348-0443
www.rswww.com

Please correct me if I'm wrong.

Thats the wrong part.
From RS the part number is 348-0566
680R SMD resistor.
A standard carbon 0.125watt 680R also fits in here easily and is very easily obtained all over.

Testing on my new AFRAME signal is going well. Although designed for the 1.6 I was suprised to see this working for all xboxes extremely reliably. I might leave a pad with the old D0 signal but I think the new signal will work for everyone.

when i installed my X3, i used a different Lframe(d0) point that the tut showed. Will cutting that trace to the lframe shown here and adding the resistor still work?

just to clarify, do i still take the same lframe point to grnd. ie the left hand red point(left side of resistor.) in your pic. thx.

bump see what modchip devs say about this

I went to radioshack and picked up a 1/2 watt 680 ohm resistor with 5% tolerance. Will this work? And also, does it matter which way the resistor is facing when u solder it in. Sorry if these questions are n00bish.

anymore input on this?

I recently did an install for a guy using an x2.6 on a v1.6 xbox.
do I need to have the guy bring his xbox back in so I can do this to it?

and all I do is solder the resistor and cut the trace?
sounds easy enough.

I am planning on buying a modchip for a new 1.6 box. I was looking at X3, Xenium Ice or SmartXX - leaning toward Xenium Ice. Do any/all of these chips have the same problem that is described in this post?

well the smartxx chips now come with a 1.6 lpc rebuild kit...when i get my rebuild kit in ill let you know if it can fix this or not

Great research, this will definitely save many XBoxes . I love my 1.0.

EDIT: However, as this is a great method, I do remember reading an older manual from SmartXX that seemed to draw current and ground it while simultaneously completing the same result. It seems that have the current withdrawal featured in this new device that you can order from them for the bottom side of the 1.6 motherboard.

See it here: http://smartxx.com/manuals/manuals_pinheader_16_v2.php

SmartXX developers truely are geniuses. As you can see, this device interacts with the LPC, which means the data and current from the board are flowing through the LFRAME quicksodler device as well as the smartxx chip. It also seems that the device utilizes one extra point on the LPC, the name of which is not specified. However, I'm sure you have already, but be sure to contact Team SmartXX and see what they think on your experiment. They seem to be the more intelligent of the modchip developing teams. I ahve a SmartXX, and it's easy to tell they worked hard and made a truely amazing piece of hardware and an astounding package of software.

Anyway, keep going with this.

EDIT: Nevermind what I said about the extra LPC point utilization. I rechecked the image and it's obvious to tell that there is no lead on the PCB. I just have to wonder what that point does. It's a possibility that it makes it easier for Live to get data from the PCB.

Just done this to a couple of 1.6 boxes and they work fine with the mod done.

i have done this on 2 boxes and it works great

I bought a Xenium Ice and was supposed to get it done earlier this week, but I guess not having time was a good thing because I came across this post. I am very new to this stuff, are there any users who can post a pic of this extra protection so I can show my guy?

Thanks!
Lor

Just saw the diagram link,sorry

this is good stuff. I just got my 1.6 today and ordered an X3. I'm definitely going to use the resistor as I don't want to ruin this new toy. One question though:
I was comparing the image originally posted (top of the very first post in this thread) with the URL=http://http://www.teamxecuter.com/x3/tutorials/x3pin16.htm]X3 install tutorial for 1.6 pinheader[/URL](had to save the original 'resistor install' image local, and flip it upside down to match the two up), and I noticed that there is an extra LPC connection on the resistor install pic.

If you are looking at the resistor install image "non-flipped" its in the second row
five down and runs almost straight to the left.

Can anyone tell me what this connection is? Does not having this connection affect the X3 install?

Very, very interesting.

I have recently purchase a batch of Aladdin XT lites. I have wired my first install for an "always on" config by grounding the D0 ( Lframe ) on a 1.6 xbox. So, if I get what you're saying correctly, by installing a 680 ohm resistor between said points in the diagram ( in lieu of a direct ground ), I can alleviate worries about prematurely overdriving the xboxes D0 output?

Is there a wattage rating of the resistor? Do you have a part number for the surface mount component? If the surface mount resistor isn't available, can I use a standard resistor? I'd like to safe gaurd my handiwork, by taking this precaution. TIA!

One other point....are the lpc rebuild pcbs ( Smartxx, Aladdin, ect, ect.... )addressing this problem?

68mA?! I'm surprised you can't smell it..
Awfully nice of you to take the time to explain it in such detail.. Hopefully this will save more xboxes than it kills.. Not through any fault of catdog2, I'm just picturing a 14 year old kid taking a steak knife to his data tracks..

so the question i have is if u use a dpdt switch y not just y not have a wire on both d0 points on either side of the trace u break and have when u turn the mod off u fip the switch so that direction is making contact to the 2 d0 points and the unmodded mode works and no resistor needed

That would work, but it is unnecessary to dink with a switch.. if a 680Ohm resistor takes it down to ~5mA that is perfect..

So is this mod needed with the Xenium Ice? Anyone know for sure?

Lor

I have a SmartXX, but it's a 1.0 XBox. However, I would sitll like to know how to measure and/or observe the release of LFRAME from the chip.

For those of us asking about Xenium ICE. I posted at TeamXodus asking if this was an issue with the Xenium ICE and got this response from the moderator:

"The Xenium ICE does not short the LFRAME to ground like 3rd gen chips and cheapmods require, therefore this 'problem' doesn't apply.

The Xenium ICE actually controls the D0 with digital pulses from its CPLD, so you don't have to worry about this issue at all."