First post, by dominik0801
Hello!
I just got a 486 motherboard. It had a barrel battery, which of course leaked, and many traces and connections have been corroted to the point of not working anymore. I fixed those traces (or hopefully I fixed them all), they were mostly power lines, and 2-3 data lines. When I finished, I also replaced a few tantalums, so I won't have any problems with them in the future.
I was about to test the board, so I put in the only 486 CPU I have (ST DX-40), and jumpered the board to a 80486DX 5V CPU.
I fired it up, however, nothing happens at all. The PSU is on, it's fan is spinning, but the motherboard won't post, won't beep or anything. The CPU gets slightly warm over time, but not hot, and it's not getting warm fast either.
So I tried out many things, like re-checking the jumpers, trying another RAM, re-seating the KBD and BIOS chips.. however, nothing helped. I unfortunately don't have another 486 CPU, and also, don't know for sure if mine works at all.
Then I started measuring voltages, and noticed, that the -5V line has -6.80V coming out of the PSU.. so I switched to another, which had the right output voltage, but that just didn't help.
I read a similiar topic here, where the problem to the OP was a bad RAM configuration, so I would like to ask for some help, since I don't exactly understand it, but want to rule this out before jumping onto another part.
This is where I found the configuration: https://stason.org/TULARC/pc/motherboards/S/S … SA-VER-4-2.html
How should I jumper the board, and which RAM slot should I use, if I only want to use a single 16MB 72pin memory?
Thanks in advance,
Dominik.