HaHaa that is not a Baby AT board by my standards 😀 That looks like a standard AT sized that nearly all Asus, etc used. added: yes they call it a baby AT but not compared to those 8.5" x 9" boards ;p
The silver serial number sticker with Made in Tawain ROC look familar but am having a brain fart and cannot recall which of my old boards has same thing. Will dig around but it may take some days....

I do NOT recommend a CR2032 battery for this board. You already have a pin header just above the keyboard socket for an external battery. I recommend 3xAA lithium primary (not rechargeable!) batteries in a holder. Connected via a dupont connector, no modification to the motherboard required whatsoever

Horun wrote on 2021-08-09, 01:02:

HaHaa that is not a Baby AT board by my standards 😀 That looks like a standard AT sized that nearly all Asus, etc used. added: yes they call it a baby AT but not compared to those 8.5" x 9" boards ;p
The silver serial number sticker with Made in Tawain ROC look familar but am having a brain fart and cannot recall which of my old boards has same thing. Will dig around but it may take some days....

I suggest you re-check your standards. That is baby AT. Full AT has a large additional section above the AT keyboard connector (or below, in this pic):

Almost everyone used babyAT as full AT was so huge and rarely needed after transition from discrete logic to integrated chipsets. So OP is entirely correct that his board is babyAT.

Can you boot the board? It might be too old - got very limited experience in anything older than S7 boards myself - but if if it was a thing back then too, it might show a BIOS manufacturer code during POST, that can be very helpful when trying to identify it.

https://www.wimsbios.com/aminumbers.jsp

I'd like to thank everyone for their fast replies.
maxtherabbit Thanks for your recommendation, I'm not too surprised, that a cr2032 is everything but ideal for a board like this.
Unfortunately, I fear, there isn't any space for a external battery.
I forgot to mention, that the system, this board belongs to, is a crammed mess, with very little space.
The power supply sits right above the battery and keyboard connector, so installing a external battery is next to impossible.
Do you have any other suggestions for me? In worst case scenario, I might have no choice, but to buy a barrel battery.

kaputnik In the moment, I can't boot the board, at least not with a monitor.
As I already said, I still need to get a VGA/SVGA first, before I'll be able to boot the system.
The LCD Panel of the Portable is damaged, so I doubt there will be anything displayed there.
However, I have a post-card, so we can at least tell, if this board works or not.

That's like EEATX which also extends beyond the PS/2 connectors.

Wilius wrote on 2021-08-09, 11:05:

kaputnik In the moment, I can't boot the board, at least not with a monitor. As I already said, I still need to get a VGA/SVGA f […]
Show full quote

kaputnik In the moment, I can't boot the board, at least not with a monitor.
As I already said, I still need to get a VGA/SVGA first, before I'll be able to boot the system.
The LCD Panel of the Portable is damaged, so I doubt there will be anything displayed there.
However, I have a post-card, so we can at least tell, if this board works or not.

Ah, sorry, must have missed that.

If it's important enough and you got the means, you can always dump the BIOS image off the chip, and get the manufacturer code using a suitable BIOS editor. Sometimes you can even get the make and model in plain text 😀

kaputnik I beg your pardon, but i'm not very familiar and confident with such things, I think it's probably easier to grab a cheap graphics card off Ebay instead.
I hope you don't mind.

Talking about "mind", there is yet another question which is on my mind.
When I first searched for shorts, I used a multimeter to check for continuity.
I connected a alligator clip to the grounded shield of the keyboard connector, and used the other tip to check each pin of the AT connector for shorts.
There wasn't any shorts.
Still, I want to make sure, that there isn't anything, that I might have missed.
Is there a better method to determine, wheter the power rails are shorted?
When nothing is shorted, I can hook it up to a known-good power supply to do the smoketest.
In case everything goes well, I will then connect a speaker and a POST-card.
In theory, there should be at least some sort of beep or POST code, that tells us, if something is wrong with it.

You have an ISA POST card but no ISA graphics card? You sound as organised as me (except that I have boxes full of graphics cards - just couldn't find any one of them without a big search) 😀

debs3759 wrote on 2021-08-09, 18:33:

You have an ISA POST card but no ISA graphics card? You sound as organised as me (except that I have boxes full of graphics cards - just couldn't find any one of them without a big search) 😀

I have the opposite problem - can't find my beautiful vintage ISA POST card. Have ISA VGA card, but no image and no beeps makes me very curious what port 80 is trying to tell me...

Wilius wrote on 2021-08-09, 11:05:

I'd like to thank everyone for their fast replies. maxtherabbit Thanks for your recommendation, I'm not too surprised, that a cr […]
Show full quote

I'd like to thank everyone for their fast replies.
maxtherabbit Thanks for your recommendation, I'm not too surprised, that a cr2032 is everything but ideal for a board like this.
Unfortunately, I fear, there isn't any space for a external battery.
I forgot to mention, that the system, this board belongs to, is a crammed mess, with very little space.
The power supply sits right above the battery and keyboard connector, so installing a external battery is next to impossible.
Do you have any other suggestions for me? In worst case scenario, I might have no choice, but to buy a barrel battery.

kaputnik In the moment, I can't boot the board, at least not with a monitor.
As I already said, I still need to get a VGA/SVGA first, before I'll be able to boot the system.
The LCD Panel of the Portable is damaged, so I doubt there will be anything displayed there.
However, I have a post-card, so we can at least tell, if this board works or not.

worst case scenario make the pigtail for the battery wire long and you can route it out the back of the case and velcro it to the rear panel

debs 3759 Yeah this is kind of embarrassing. You got me there, i'm indeed not very organized. I should really consider getting one ASAP.
I usually don't collect hardware quite this old. Especially not in such formfactor. I'm more into the ATX, PCI and AGP era.

maxtherabbit That sounds like a awesome idea. I'll definitely do that. Thank you.

dionb wrote on 2021-08-09, 06:13:

I suggest you re-check your standards. That is baby AT. Full AT has a large additional section above the AT keyboard connector ( […]
Show full quote

Horun wrote on 2021-08-09, 01:02:

HaHaa that is not a Baby AT board by my standards 😀 That looks like a standard AT sized that nearly all Asus, etc used. added: yes they call it a baby AT but not compared to those 8.5" x 9" boards ;p
The silver serial number sticker with Made in Tawain ROC look familar but am having a brain fart and cannot recall which of my old boards has same thing. Will dig around but it may take some days....

I suggest you re-check your standards. That is baby AT. Full AT has a large additional section above the AT keyboard connector (or below, in this pic):

Almost everyone used babyAT as full AT was so huge and rarely needed after transition from discrete logic to integrated chipsets. So OP is entirely correct that his board is babyAT.

Guess you did not read my comment with the idea I was joking around a bit (the HaHaa parts). I do know what Intel say is AT standards (they did set it) but by "my standard" your board picture is full AT, where his is standard AT and those mini AT boards (like the micro AT 386) are baby AT. Hmmm ever wonder why when ATX came out they have so many descripters (standard, micro, mini, nano, pico) but did not do that with AT ? 😁

There was a plan for a plus sized AT, the AT squared or AT-AT, but cable length tripped it up 😉

I know i'm asking a lot of questions. You are probably tired of it, which is understandable. But I just want to be sure to make the right decisions.
Though I have no other ISA card with a VGA connector, I have a 8-bit ISA card with a connector, which seems to be a CGA or EGA port.
The chipset is a Yamaha V6366B-F. It appears to be a MDA/CGA/Hercules chipset.
Would it be cheaper if I purchase a CGA/EGA to VGA adapter, or would I be better off, if I buy a different graphics card.
The cheapest card i've found costs 27,00€ or 31,68$ shipping included.
Is it safe to test this motherboard yet, or do I need to provide more informations, in order to make sure, that it's actually safe to test my board?
I'm extremely concerned, because I don't want to blow anything up.

Wilius wrote on 2021-08-10, 02:18:

I know i'm asking a lot of questions. You are probably tired of it, which is understandable. But I just want to be sure to make […]
Show full quote

I know i'm asking a lot of questions. You are probably tired of it, which is understandable. But I just want to be sure to make the right decisions.
Though I have no other ISA card with a VGA connector, I have a 8-bit ISA card with a connector, which seems to be a CGA or EGA port.
The chipset is a Yamaha V6366B-F. It appears to be a MDA/CGA/Hercules chipset.
Would it be cheaper if I purchase a CGA/EGA to VGA adapter, or would I be better off, if I buy a different graphics card.
The cheapest card i've found costs 27,00€ or 31,68$ shipping included.

If you can find an MDA/Hercules to VGA adapter for less than that, let me know! They tend to cost a lot more.

But... MDA/Hercules/CGA cards also freqeuntly have composite-out via an RCA connector. If you have a television (or any other display device) with composite-in, you can hook that up. Don't expect good picture quality, but you can see if it boots.

In general, if you're messing around with boards of this age, you want a known-good ISA VGA card.

Is it safe to test this motherboard yet, or do I need to provide more informations, in order to make sure, that it's actually safe to test my board?
I'm extremely concerned, because I don't want to blow anything up.

For complete safety you could use something like the ATX2AT Smart Converter, but if you've already measured the tantalum caps and they're not shorted, the risk is small. Still, they could fail spectacularly on powering on. I'd be more worried about my eyes than my hardware, a pair of safety goggles might be an idea if you don't wear glasses.

BitWrangler wrote on 2021-08-10, 01:47:

There was a plan for a plus sized AT, the AT squared or AT-AT, but cable length tripped it up 😉

AT-AT? Wasn't that one of those walking tanks in Star Wars?

debs3759 wrote on 2021-08-10, 16:27:

BitWrangler wrote on 2021-08-10, 01:47:

There was a plan for a plus sized AT, the AT squared or AT-AT, but cable length tripped it up 😉

AT-AT? Wasn't that one of those walking tanks in Star Wars?

Yeah, that was the joke...they took one down with a long cable... from the 2nd Star Wars movie, Episode 5, Empire Strikes Back, which is now the 7th in Chronological sequence or 8th if you include Clone Wars animated, possibly the 19th or so by the time they're done turning that horse to mulch, and I ain't got a clue where Mandalorian fits.

dionb wrote on 2021-08-10, 10:05:

but if you've already measured the tantalum caps and they're not shorted, the risk is small. Still, they could fail spectacularly on powering on.

Yeah... about those tantalum capacitors.
So far I've only tested 3 of the many tantalum capacitors, mainly near the power connector.
I testet each leg with each pin and hastly made a diagram with Paint, that shows on which pin the multimeter started beeping.
(graphics design isn't my passion at all)
Note: The pinout for the AT connector is flipped, because it represents the backside of the board.
I'm lacking the required know-how to understand whether these caps are supposed to be like that.
Therefore, I hope that you can tell me, if everything looks like it should be.