Troubleshooting Mobo From Bios Socket

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Troubleshooting Mobo From Bios Socket

Postby miki02131 » Thu Jan 22, 2009 7:52 pm

Hello Guys,

Let say that we provide power to an out-of-case mobo that has nothing connected or attached to it including the bios chip. Let's call this state zero. For a 32-pin bios socket, what voltage level should each pin measure? Are the readings the same or common to all motherboards or are they different?

Now suppose that the bios chip is mounted on the socket, how this will affect the readings? What readings are to be expected at boot up and after bootup?

Thanks,

Miki.
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Postby evasive » Fri Jan 23, 2009 3:56 am

It depends on what size the bios chip is and what type too, they can have different programming voltages and different pin layouts. If you give us info on what brand/model the board is, we might be able to retrieve what bios chip it uses and thus the layout with voltages.
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Postby miki02131 » Fri Jan 23, 2009 9:59 pm

Evasive,

The chip is an SST39F020A/5V. It is 256k award bios.

After thinking about it, I think these readings may depend on the motherboard default configurations. We may not be able to characterize all mobo based on these parameters alone.

The idea was to develop a simple procedure to test a barebone mobo just by reading the output voltage at the bios chip. This is a logical place to choose since this is the system starting point. We could have used the pci or isa pins for that but this approach is not really a primitive approach.

The most primitive approach is to read the voltage levels from the bios socket pins. I did some readings from 3 old motherboards today, they seem to be all different. The plan is to get data for as many board as possible and use this data to develop the mobo testing procedure.

If anyone willing to participate and provide data, this can help speeding up this project. The other approach is to see if we can get the data from the mobo manufacturers directly but I doubt they will provide them.

I will post my data later if people are interested.

Thanks,

Miki.
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Postby evasive » Sat Jan 24, 2009 1:49 am

Umm isn't there somthing called a POST card that does the same? What exactly do you want to test for? The amount of "deadness" of a board as in between could be alive/most definitely fubar?
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Postby Copper » Sat Jan 24, 2009 2:32 am

with so many chips , copper tracks and other bits your on the road to no where

all motherboards are tested with a cpu and ram

voltage readings alone wont diagnoze a faulty motherboard
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Postby evasive » Sat Jan 24, 2009 11:09 am

this might save a CPU/memory stick or two from getting fried by a completely fubar mobo... I can see where this came from. Might be a better idea to identify the CPU pins that do matter (e.g. the supply pins) and measure there with a multimeter before putting in a cpu.
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