SUCCESS
Nobody answer but I will write here what I learned. Maybe someday it will be useful for somebody. So:
1. Connectors ST3 and ST4 must be connected to X10. Without this connection computer will not post. I still don't know what is X4 NMI and X11.
2. Computer will not run with memory in bank 3 and 4 . Memory modules must be in bank 0 and 1 so now I have to desolder these sockets and solder good ones into bank 0 and 1.
Now it is time to wash the case and build nice 386SX.

That's a cute little PC 😀 Didn't know it exists

Tomek TRV wrote on 2023-08-19, 19:02:

SUCCESS
Nobody answer but
.....

Pictures would have been helpful to catch the attention of readers.

Nevertheless, good job.

Tomek TRV wrote on 2023-08-19, 19:02:

SUCCESS Nobody answer but I will write here what I learned. Maybe someday it will be useful for somebody. So: 1. Connectors ST3 […]
Show full quote

SUCCESS
Nobody answer but I will write here what I learned. Maybe someday it will be useful for somebody. So:
1. Connectors ST3 and ST4 must be connected to X10. Without this connection computer will not post. I still don't know what is X4 NMI and X11.
2. Computer will not run with memory in bank 3 and 4 . Memory modules must be in bank 0 and 1 so now I have to desolder these sockets and solder good ones into bank 0 and 1.
Now it is time to wash the case and build nice 386SX.

Hi!
I have exactly the same computer. It was working good, stored in my wardrobe for many years but when I saw your post I took it out to see what's connected where inside the case to help you.
I then realised that it's not working anymore. I measured the psu rails with a multimeter, they seem fine. I reseated the wdc vga card and the memory, but still no signs of life. I don't know what else to check. I had removed the nicd battery years ago, I remember it posting without the battery connected.
The hdd spins up fine so the psu should be ok, but nevertheless I tried unplugging the ide and floppy cables but no luck. CPU gets warm. My memory slots are not broken.

It would be good to have diagnostic card. Then You could see is there any activity. At Your place I would disconect everything what is possible, all connectors but also pull out BIOS chips and assembly everything again. After so long time there may be some oxidation and, like in my case, take care about ST3 and ST4 connectors. Also it would be good to try with other simms. There is not much things that could damage on this motherboard, no electrolitic caps, no Varta (my Maxel is dead but not leaking). I hope You will bring it back to life.

Tomek TRV wrote on 2023-08-20, 21:19:

It would be good to have diagnostic card. Then You could see is there any activity. At Your place I would disconect everything what is possible, all connectors but also pull out BIOS chips and assembly everything again. After so long time there may be some oxidation and, like in my case, take care about ST3 and ST4 connectors. Also it would be good to try with other simms. There is not much things that could damage on this motherboard, no electrolitic caps, no Varta (my Maxel is dead but not leaking). I hope You will bring it back to life.

That's a little too late, but I had time to see what's wrong with this system. Well, I took out the mainboard because I couldn't see anything wrong with it. It turned out the backside was a complete mess, a lot, and I mean A LOT of traces were just not there due to corrosion. On a quick look I could spot 20 or more of them. I was super sad, but that little Siemens beauty is not going to trash. I ordered a (much newer) Pentium III SBC that will go in there and I'll have to hack an ATX (or better: SFX) psu somehow.

It's a pity that it is so badly damaged, but I would still try to repair it first. Can You add some photo here?

As you can see it's a real mess... 🙁

Tomek TRV wrote on 2024-07-26, 20:43:

It's a pity that it is so badly damaged, but I would still try to repair it first. Can You add some photo here?

In my opinion it is not so bad. I would try to fix it.