First post, by tony359
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Hi all,
I am diagnosing an Acer V58 - https://theretroweb.com/motherboards/s/acer-v58#docs - the manual is like 95% accurate as I see something is not there.
I took a look at this board in one of my videos, first box: https://www.youtube.com/watch?v=pEeNqD2FOHQ
The board appears to be dead. The CPU is getting proper voltage, proper clock and the reset line works. But there is no code being executed.
I see NO activity whatsoever on the BIOS address/data lines.
I tried Deksor's 80h test BIOS - it works on a different MoBo but not on the V58.
I am following some leads. One being that all the BIOS data lines are like 2.5V as it there was something conflicting on the bus. I noticed the relevant 245 buffer IC is set to "B to A" that is, ISA to BIOS. It's weird as I'd expect that at that early stage it should be "BIOS to BUS" - but I am still looking into that.
I would like to understand better what happens when a system is powered up. I suppose the CPU will reach for the BIOS so I should see some address lines coming to life and then some data being exchanged on the BUS? Is that coming from the CPU itself? In other words, I am going to probe the address/data lines at the back of the CPU, am I supposed to see something there when RESET is released?
Oh and of course the CPU and the RAM do work on a different motherboard.
Thanks for now!
My Youtube channel: https://www.youtube.com/@tony359