Update: I soldered additional 5V and GND wires, -12V and found a manual here: https://f.ipc2u.ua/files/add/doc/495/pcisa-158hv.pdf (jumpers seem to be OK)

Tried with a better power supply. It is still not working, it keeps beeping indefinitely after turning power on.

RAM is OK (tested in another machine), swapped the CPU and the result is the same. If I remove BIOS chip, it is not beeping at all.

I see no apparent physical damage.

This board has DS12C887 RTC, most likely with a dead battery inside. Does anyone know if discharged Dallas RTC can cause blank screen and no POST with with Award 586, SiS 5598 boards?

I've had quite a few motherboards that refused to boot with a dead Dallas chip. I'd see if you can mod the Dallas with an external battery and see if the board posts after. There's quite a few threads here on vogons to mod the Dallas

All right, i will solder a socket and experiment with modded chip or replacement. Hope that helps, not sure what to do if not. BTW i didn't see a mod on DS12C887, hope it looks the same on the inside as the other variants, otherwise i will need to guess the battery polarity.

I'd give the board a good look over for any chips with bent/touching legs or and signs of physical damage. But odds are it's just the Dallas chip having a dead battery

chrismeyer6 wrote on 2020-07-28, 14:38:

I'd give the board a good look over for any chips with bent/touching legs or and signs of physical damage. But odds are it's just the Dallas chip having a dead battery

Yeah, i inspected the board and it's quite obvious it was abused because chips are scratched, i got different board (also SBC but different chipset) from the same pile and it had one chip almost sanded off the board, like it was dragged on floor, and had two missing components. But it worked just fine after resoldering them. I see no missing components here, only place I didn't look at is underside of voltage regulator module. It looks like it is inserted into a goldpin socket, but I can't pull it out, maybe it is glued in, I don't know. But the voltages are there.

From my experience it's probably just a dead battery in the Dallas. I've replaced the the Dallas or modded for a external battery and got 5 mother boards fully functional

So I drilled into battery terminals and it shows 2.93V... maybe this RTC is just damaged, but otherwise I would need to look for another reason

That is technically below the 3 or so volts some boards are really picky about battery voltage.

I just found that EliteMT TAG RAM chip LP1256GS-12 has pins A14, CE, OE shorted to ground (VCC is okay though), and a ceramic capacitor on the other side of the board, underside TAG RAM is shorted. I guess that it isn't the way it should behave.
Maybe it will lead me somewhere... I guess i should desolder capacitor first, and TAG RAM next.
//Edit: capacitor is fine, so I guess it's time for hot air station rework...
//Edit2: still shorted after removing TAG RAM...

Hi, did you managed to boot it up?
I just got the same board from a friend. It's populated with ceramic Pentium MMX and 2 SIMMs, no DiskOnChip. Unfortunatelly the ZIF CPU socket has missing the lever so the CPU pins are not secured to have good contact. I have no idea who did what with it. I have to found some spare socket and try to repair it. The rest is mechanically in good condition, no scratches, etc.
I doubt the Dallas RTC would be a problem, 2.93V seems to me fine after the years, the memory should hold data down to 2.5-2.8V or so. But it's not problem to grind off the top and solder a CR2032 holder on top of dallas to replace old battery.
Here is working link to manual if someone else would need it:
https://www.stockcheck.com/product/iei-techno … rds-1/pcisa-158
And PISA bus spec.
https://www.kontron.com/download/download?fil … rs/pisad218.pdf
Any BIOS update found?

Did you tested what voltages are really needed to boot up? 5V or 12V or both? I think no need for negative voltages as it's used probably only for RS232. Manual says:
Power Consumption : +5V @ 4.6A ( Pentium/MMX-200,16MB EDO RAM)
+12V @ 70mA , -12V@20mA
So +12V is not used for VRM and probably nothing system critical.

I made some steps further:
I replaced the damaged ZIF socket 7 with one desoldered from another MB
I fixed VRM module that has blown tantalum capacitors on bottom side and replaced one elyt that completly lost capacity. Also I have to replace elyts around CPU socket (almost dead too).
I found that VRM module needs +5V and also +12V for driving MOSFET gates. Now VRM operates OK and I measured 2,8V core and 3,5V outputs. I also grinded off Dallas RTC and put new backup battery on. But the board is still dead, any beep 🙁
I will have to check clocks and try to make some adapter to attach POST card or at least watch IOWR#...

hallo
i have this board too.(PCISA158V)
and i am looking for the manual.
all directions are dead now.
please can you help me.
dietrich simon

I found some manual for PCISA – 158HV somewhere, don't remember link so I put as local download.

Onboard Power Module pinout:
1 - 2,8Vcore-out
2 - 2,8Vcore-out
3 - 2,8Vcore-out
4 - 3,5Vout
5 - 3,5Vout
6 - GND
7 - GND
8 - GND
9 - 5Vin (needed for operation)
10 - 5Vin
11 - 5Vin
12 - 12Vin (needed for operation)

RayeR wrote on 2022-10-30, 13:06:

I found some manual for PCISA – 158HV somewhere, don't remember link so I put as local download. […]
Show full quote

I found some manual for PCISA – 158HV somewhere, don't remember link so I put as local download.

Onboard Power Module pinout:
1 - 2,8Vcore-out
2 - 2,8Vcore-out
3 - 2,8Vcore-out
4 - 3,5Vout
5 - 3,5Vout
6 - GND
7 - GND
8 - GND
9 - 5Vin (needed for operation)
10 - 5Vin
11 - 5Vin
12 - 12Vin (needed for operation)

hallo

thank you very much, this helps very good.
i have this board with metalbox with powersupply and motherboard.
it is a nice small retro computer when it works.
now i have a chance.
dietrich simon