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Lad2 Low Voltage


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#1 millican

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Posted 04 April 2005 - 02:56 PM

I've posted before about this box but since I found an obvious problem I will post about it separately and see what kind of responses I get.

It's a v1.0 that's been in a coma. The 3 wire trick didn't work and neither did a DuoX2 chip, it still boots up to a solid green led, no video, no sound and no eject.

The DuoX2 chip has been tested in another Xbox. I have swapped out the DVD drive, IDE cable and yellow DVD power cable. No change, it's still a coma. I removed all mods, back to stock form.

I tested the LPC with power on and found a problem. On pin 8 (Lad2) I got .67V and should have got 3.3V or about that. I used my Fluke 77 and did an ohm check from Lad2 following it's trace back to the closest Via and it was good. I can't go past the Via because it is under the MCPX. Does anyone know if this is an output from the MCPX or an input? If it's an output what could be missing going into the MCPX to trigger this output?

Is there a topside alternate Lad2 point?

#2 networkBoy

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Posted 04 April 2005 - 04:30 PM

It's both an input and output.

Can you measure the resistance between the lad and pin 15 (3.3V)?
It should be around 10Kohms.
-nB


#3 millican

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Posted 05 April 2005 - 04:31 PM

QUOTE(networkBoy @ Apr 4 2005, 09:36 AM)
It's both an input and output.

Can you measure the resistance between the lad and pin 15 (3.3V)?
It should be around 10Kohms.
-nB

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I get 8.87M ohms between Lad2 (pin 8) and 3.3V (pin 15) with power off.



#4 networkBoy

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Posted 05 April 2005 - 05:09 PM

The 10K pull up resistor is dead. I sell replacements 3/$2.00 if you're interested.
-nB

#5 millican

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Posted 05 April 2005 - 07:24 PM

QUOTE(networkBoy @ Apr 5 2005, 10:15 AM)
The 10K pull up resistor is dead.  I sell replacements 3/$2.00 if you're interested.
-nB

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Yes, I am interested. I sent you a PM for ordering details.

#6 networkBoy

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Posted 05 April 2005 - 07:50 PM

It's R7D8 for anyone else following this wink.gif
-nB

#7 millican

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Posted 06 April 2005 - 08:32 AM

QUOTE(networkBoy @ Apr 5 2005, 12:56 PM)
It's R7D8 for anyone else following this wink.gif
-nB

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Are you sure it's not R7D6 on a V1.0 motherboard?

I looked at my motherboard and I couldn't find a R7D8 near the LPC.

#8 networkBoy

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Posted 06 April 2005 - 03:10 PM

If you are looking at the MB with the front facing you:
It is the bottom of three resistors in a row directly to the left of the LPC connector by about 2 millimeters.
-nB

#9 millican

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Posted 07 April 2005 - 04:21 AM

QUOTE(networkBoy @ Apr 6 2005, 08:16 AM)
If you are looking at the MB with the front facing you:
It is the bottom of three resistors in a row directly to the left of the LPC connector by about 2 millimeters.
-nB

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Yup, that's the one I'm talking about. On a V1.0 it is labled R7D6 and mine is missing ohmy.gif

#10 networkBoy

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Posted 07 April 2005 - 03:11 PM

Yup. Sorry I was looking at a 1.1 (once they're stripped there is little difference between them. This is one though :oops:
-nB

#11 millican

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Posted 18 April 2005 - 03:49 PM

Success biggrin.gif

I fixed the low voltage on Lad2 by replacing the missing resister next to the LPC that must have been knocked off by the previous owner that tried a mod chip to fix this box I bought from him. After I replaced the resister by voltage was correct at Lad2 but the Xbox was still in a coma, no video, audio of eject.

I and fellow board members suspect a bad eeprom flash so I embed a X2 4981 bios with a V1.0 eeprom and booted up. To my surprise it worked! I now had a working Xbox, mind you I had to swap out the stock hard drive with a unlocked hard drive because the eeprom had changed. I didn't have the original eeprom.

After loading my dash of choice I quickly run ConfigMagic and flashed the on-board eeprom correctly unlike the original owner. Once the on-board eeprom was flashed I then changed my mod chip back to a standard 4981 bios without the embed eeprom to prove my work. Success again, I now have a fully operational Xbox again.

beerchug.gif Cheers Xbox Scene, you guys/gals rock!


#12 boowhup

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Posted 20 April 2005 - 11:42 AM

I have a similarly coma'd console, the resistors are all in place, but even with a modchip it still coma's, Ive tried tying down a19 and a18 to no avail. What does work is an x2.6ce with flashbios, but as soon as I flash an x2/evoX bios on it it coma's, would this suggest the eeprom is hosed?

I have repaired an eeprom before, but (cleverly enough NOT) didnt keep the prom backup, and cbf doing one up unless theres a pretty good chance it's going to work.

Any help would be appreciated biggrin.gif Or if theres another fix.

QUOTE(millican @ Apr 18 2005, 02:55 PM)
Success  biggrin.gif

I fixed the low voltage on Lad2 by replacing the missing resister next to the LPC that must have been knocked off by the previous owner that tried a mod chip to fix this box I bought from him. After I replaced the resister by voltage was correct at Lad2 but the Xbox was still in a coma, no video, audio of eject.

I and fellow board members suspect a bad eeprom flash so I embed a X2 4981 bios with a V1.0 eeprom and booted up. To my surprise it worked! I now had a working Xbox, mind you I had to swap out the stock hard drive with a unlocked hard drive because the eeprom had changed. I didn't have the original eeprom.

After loading my dash of choice I quickly run ConfigMagic and flashed the on-board eeprom correctly unlike the original owner. Once the on-board eeprom was flashed I then changed my mod chip back to a standard 4981 bios without the embed eeprom to prove my work. Success again, I now have a fully operational Xbox again.

beerchug.gif  Cheers Xbox Scene, you guys/gals rock!

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#13 boowhup

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Posted 20 April 2005 - 11:59 AM

Got off my lazy ass and did it anyway, and It works , so I guess it was the same thing biggrin.gif

#14 rwarrin

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Posted 21 April 2005 - 12:12 AM

I have what appears to be the same problem and I want to test out what you guys have found but I have a couple questions. I have a 1.1 board and I have found the 3 resistors to the left of the 16 pin header. Mine are label R7D4, R7D5, R7D6 and form what you say is that R7D6 could be bad. I dont understand what you are saying when you say measure the resistance between the lad2 and pin 15. What is the lad2 is that pin 8 on the same pin header (also where the X3 solders into). Are you just checking between pin 15 and 8 on it. I don't have the x3 on it at the moment so I just have open holes there. If you guys can confirm this I can get this resistor replaced ASAP. Thanks for any help.

#15 rwarrin

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Posted 21 April 2005 - 01:24 AM

I tested between pin 8 and pin 15 and have 10K and 3.29 volts on pin 8 when powered up so no luck there. My problem was video freezing randomly until the video just quit. The TV does get a signal when the XBOX turns on it goes blank and the word stereo pops up on the screen there is just no sound or video. I also noticed the 12 volt line gets pulled down to about 11 volts and all the 3.3 volt lines go up to about 3.6 volts, the 5 volt stays where its at. If anyone has any ideas let me and I will try them.




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