First post, by majestyk
- Rank
- Oldbie
I recently dug out this ancient 386 25 MHz mainboard and was happy someone had removed the battery IN time.
This mainboard must have been available under several brands. It´s identical with Shuttle´s HOT-304, the Magitronic A-B323 and others.
I cleaned it, checked everything visually, put a CPU and RAM in and gave it a try. It´s starting, complains about "low CMOS" battery", finishes the memory test and - detects exactly 1024 KB, even when there´s 4MB or 8MB put in the banks.
I tried countless sets of memory, 3-chip and 90-chip sticks. I also tried different BIOSes since the board didn´t come with the original BIOS. -> still 1024 KB.
Then I found significant corrosion at one of the three 74F244N Buffers (this one also didn´t get warm, unlike the other 2):
So I removed it, cleaned everything, put a 20-pin DIL socket in it´s place and a new 74F244N in it. This one gets warm now, like the others, but -> still 1024 KB.
The 8 SIMM sockets are the uncool type where you have to press the sticks vertically down with force. All retentions were broken, the sockets were worn out anyway, so I replaced the 1st four of them with new Amphenol sockets. But, still 1024 KB.
I have checked the backside carefully, measured countless traces that have scratches - everything seems fine there.
So I´m running out of ideas at the moment.
