No luck yet finding anything. If you could get the BIOS string it would help in searching. Do you have a eeprom programmer to read the bios chip ?

I would try to remove the RAM at 30 PIN, and put a SIMM at 72 PIN, and see what happens, theoretically apart from those jumpers near the RAM, the rest could be understood, looking at what is connected.

I don't know by heart what C1 is, if it's something that concerns RAM, maybe there's still some track that should be fixed (?)

Good idea ! from my little book C1 is "test size on-board memory" or "detect presence of ram". Might need to try one, then two 4Mb 72pin, then one 8mb then 2....

Some components soldering hell?

Horun wrote on 2024-11-13, 19:37:

Good idea ! from my little book C1 is "test size on-board memory" or "detect presence of ram". Might need to try one, then two 4Mb 72pin, then one 8mb then 2....

In fact, even in my booklet it is written like this.

I thought that the problem could only be in the 30 PIN RAM bank, or that one of the four has a problem, maybe the 72 PIN banks if he's lucky 🍀, work.

If I'm not mistaken the RAM that is most frequently used in these PCs, it's the FPM one, maybe that EDO could be unrecognized (?).

Horun wrote on 2024-11-13, 17:55:

No luck yet finding anything. If you could get the BIOS string it would help in searching. Do you have a eeprom programmer to read the bios chip ?

Here. i did not see anything noteworthy.

PC@LIVE wrote on 2024-11-13, 21:48:

In fact, even in my booklet it is written like this. […]
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Horun wrote on 2024-11-13, 19:37:

Good idea ! from my little book C1 is "test size on-board memory" or "detect presence of ram". Might need to try one, then two 4Mb 72pin, then one 8mb then 2....

In fact, even in my booklet it is written like this.

I thought that the problem could only be in the 30 PIN RAM bank, or that one of the four has a problem, maybe the 72 PIN banks if he's lucky 🍀, work.

If I'm not mistaken the RAM that is most frequently used in these PCs, it's the FPM one, maybe that EDO could be unrecognized (?).

4 x KMM591000BN-7 1MB FPM. not edo/parity.

I do not have any 72 pin simms right now- will get some in coming days.

Babasha wrote on 2024-11-13, 21:12:

Some components soldering hell?

Top one, was removed for bad corrosion (replacement is on its way). its sole usage revolves around battery charging circuit. The rest of them, were like that when i got my hands on this board. Will double check them. Thanks for pointing that out.

parabellum wrote on 2024-11-13, 23:49:

Horun wrote on 2024-11-13, 17:55:

No luck yet finding anything. If you could get the BIOS string it would help in searching. Do you have a eeprom programmer to read the bios chip ?

Here. i did not see anything noteworthy.

Thanks ! The bios string: Award 05/02/94-SIS-85C461-2C4I7PA0-00
2C4I7PA0 is the key. The sixth and seventh letters are the company: PA which is EPoX. The first five are the chipset ID.
Now at least we have another place to start looking. Will dig into Google and Wayback machine and see what comes up

Your ROM checksum is fine, I can even boot an emulator with it.
On POST 0xC1 your BIOS (at F000:0806) enables CPU internal cache and sets up DRAM controller, saves user reboot (ctrl-alt-del) flag, runs a simple low memory (16*4 KB) test, beeps if the test fails, restores the flag. Then it proceeds to POST 0xC5.

parabellum wrote on 2024-11-13, 23:58:

Babasha wrote on 2024-11-13, 21:12:

Some components soldering hell?

Top one, was removed for bad corrosion (replacement is on its way). its sole usage revolves around battery charging circuit. The rest of them, were like that when i got my hands on this board. Will double check them. Thanks for pointing that out.

Recheck all smd's on motherboard! Looks like some one moves them with hot air when solderind.

PC@LIVE wrote on 2024-11-13, 21:48:

[...]

If I'm not mistaken the RAM that is most frequently used in these PCs, it's the FPM one, maybe that EDO could be unrecognized (?).

He's currently using 30p SIMMs. The only.place you're going to find "EDO" 30p SIMMs is in eBay adverts from sellers who don't know the difference between the terms "EDO" and "SIMM". If this were only happening with 72p SIMMs that could have been the cause.

Given the amount of (shoddy) SMD rework I'd either suspect that, or that was an - unsuccessful - attempt to fix the underlying problem.

Dust or dead?)))

Babasha wrote on 2024-11-14, 09:04:

Dust or dead?)))

Dust 🙁

Ok!
So resolder all strange mounted SMDs - i hope someone who solder they do this as it was from factory (not the by the size)

Babasha wrote on 2024-11-14, 11:35:

Ok!
So resolder all strange mounted SMDs - i hope someone who solder they do this as it was from factory (not the by the size)

checked all SMD components, all seems fine - most of them are bypass caps connecting gnd to 5V.

Progress!
just got two kmm5361003cg-7 sticks, installed it alongside 30 pin dimms, and IT POSTED

Remaining problems : keyboard does not work, wrong ram size - 8MB missing

parabellum wrote on 2024-11-14, 13:38:

Progress!
just got two kmm5361003cg-7 sticks, installed it alongside 30 pin dimms, and IT POSTED

Remaining problems : keyboard does not work, wrong ram size - 8MB missing

Great result, but there is still something to fix.

For RAM, it is not said that there is a problem, sometimes in the 486, you have to find the right combination, maybe if you try a single RAM at 72 pin, you will see if it is read with the right capacity, sometimes and here you would need the manual, mixing banks of different capacity, it can give strange results, less memory is seen than the one actually available, maybe if you remove the 4 RAM at 30 pins it could read 16 MB (?)

There is no RAM problem.
He has four 1MB 30 pin SIMs and two 4MB 72 pin SIMs. That is 12MB total.