Using the JTAG connector on a PC motherboard?

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Th3_uN1Qu3
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PostPosted: Wed Oct 07, 2009 6:07    Post subject: Using the JTAG connector on a PC motherboard? Reply with quote
Hey all, i need some help on this one. I have an Asus M2N-E SLI board from a friend, which booted, but displayed no video on either PCI-E slot. I have gotten it to work with an old PCI video card, and thought i'd use it as a server. Its BIOS was very old and buggy, so i updated it (using a floppy). Big mistake... The update was successful but now the board is REALLY dead. My guess would be that the new BIOS has some extra code which detects that the chipset is faulty (since both PCI-E slots are gone) and doesn't let it power on.

I only have a big old soldering gun, no way i could unsolder the BIOS chip with that. However i found that the mobo has a JTAG connector (7 pins). Could i possibly use that to reflash the old BIOS into it? Any help is welcome.

Edit: The connector looks like this:
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beyondwind
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PostPosted: Thu Oct 29, 2009 2:15    Post subject: Reply with quote
you may want to use the spi flash program called spipgm to flash the bios.

hope this link helps:
http://mondotech.blogspot.com/2009/05/asus-p5b-deluxe-bios-recovery-spi-flash.html
Th3_uN1Qu3
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PostPosted: Thu Oct 29, 2009 15:33    Post subject: Reply with quote
I've seen that, it only works with serial flashes (tiny 8-pin thingies), while mine is a Firmware Hub in a PLCC 32-pin package.

Anyway, someone i know has bought a BIOS programmer and also has the tools required to unsolder the chip, i'll drop by him and have it reflashed in the programmer.
tester272001
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PostPosted: Wed Dec 09, 2009 19:30    Post subject: jtag bios Reply with quote
Did you try the forum here:
http://www.wimsbios.com/index.jsp
if you cannot get help there you will not get you mobo running. its a great resource.
zerofire
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PostPosted: Wed Dec 09, 2009 19:33    Post subject: Reply with quote
You should try clearing the CMOS. Sometimes when the BIOS is updated the CMOS data becomes invalid and the system will display a blank screen. by clearing the CMOS you clear the data and set it to defaults making the unit boot.
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Th3_uN1Qu3
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PostPosted: Thu Dec 10, 2009 6:07    Post subject: Reply with quote
Clearing CMOS was the first thing i tried. Anyway this has become low priority, i kinda forgot about the board as i have another one.

The guys over at Wim's did help me with an Asus board a few years ago, but i don't know how much they could help on this one. I'll eventually drop by this guy with the programmer, have the chip reflashed, and it'll work.
Hellbore
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PostPosted: Wed Jan 06, 2010 0:08    Post subject: Reply with quote
Will the motherboard even turn on?

Some BIOS have the ability to boot from a floppy for re-flashing the bios. This used to be pretty common.

You make a DOS boot floppy with the bios flashing program and the original or correct BIOS image, and you set up the autoexec.bat file so that when the floppy boots, it will automatically and silently re-flash the bios, without any user input (using whatever commandline arguments the flashing program needs to bypass the confirmation questions, etc).

It needs to be automatic because you won't have any video during the process. You might have keyboard, maybe not.

I have recovered several motherboards this way. You could try hooking up a floppy to the motherboard and put a disk in and turn it on, and see if it starts reading the floppy like it's trying to boot.
Th3_uN1Qu3
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PostPosted: Wed Jan 06, 2010 4:29    Post subject: Reply with quote
I tried that before i posted. It doesn't work. The mobo powers up but does absolutely nothing.

Prior to this flash, even when it didn't have video, it varied the speed of the CPU fan several times, this was its sign of booting up. Now the CPU fan stays at a constant speed.
mekanix
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PostPosted: Sun Feb 14, 2010 5:32    Post subject: Reply with quote
Well, back to the original question..I'd be interested to see if it detects a flash chip. I suppose you'd have to use a multimeter to get which pins are which..
Th3_uN1Qu3
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PostPosted: Sun Feb 14, 2010 13:47    Post subject: Reply with quote
Umm, yes i do have a multimeter, but i didn't get your idea. To check if WHAT detects a flash chip?

You mean checking if the JTAG is connected to the flash chip? Yeah that would have been an idea. I do not have the board anymore (i gave it back to my friend, it used to sit idle on my shelf now it does the same on his shelf Razz), but i'll check that next time i drop by him.
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