Yeah, your example is pretty nice. Totally not jealous. I got mine in its original case, a horizontal under-monitor type. It had an oak vga card, and a 40 mb seagate hdd. The power supply also had this stupid little .1 inch header socket wire that was on red/black wires for some reason. The HDD light cable was on a .1 inch header with red/black wires. Mistakes were made. Goodbye, seagate ST-157a.

The pin of the battery connector closest to the keyboard port is the positive, and the one opposite is the ground. The polarity of the header basically lines up with the polarity of the battery on the motherboard. I just used a 3x AA battery holder and it's held the time for 20 hours now.

Edit: you posted the reply saying you figured out the pinout as I was typing this message, sorry for the duplicate info

Also it is very hard to get information on the TI TACT8230 chipset used on these boards. I found only one article in Computer Business Review, but no datasheets:

root42 wrote:

Traced the pinout, thanks to HanJammer:

You will be fine, just make sure not to connect more than 6V to this.
I'm using NiCD recharchable batteries rated at 1,2V (actually slightly over 1,3V fully charged) - four of them makes 4,8-5,2V so it's safe.
When using fresh AA alkalines you can easly exceed 6,2V with 4-battery holder so use 3-battery holder instead...

BTW - yesterday I built this 20MHz Octek Fox III based 286: https://www.youtube.com/watch?v=I5v2sUlYD6A.
Currently it has ZyMOS Poach 51 VGA, SB16 CT2290 and ST-157A hard drive installed...
I have some good fun with it! Unfortunatelly my 3,5" Canon Floppy drive died in it today 🙁 It's a sad day because this floppy originated in my first PC (also 286) back in early 90s...

Also, I believe that those batteries are supposed to be 3.6v, not 1.2. At least that's what mine was labeled as when I removed it.

dkarguth wrote:

Yeah, your example is pretty nice. Totally not jealous. I got mine in its original case, a horizontal under-monitor type. It had an oak vga card, and a 40 mb seagate hdd. The power supply also had this stupid little .1 inch header socket wire that was on red/black wires for some reason. The HDD light cable was on a .1 inch header with red/black wires. Mistakes were made. Goodbye, seagate ST-157a.

The pin of the battery connector closest to the keyboard port is the positive, and the one opposite is the ground. The polarity of the header basically lines up with the polarity of the battery on the motherboard. I just used a 3x AA battery holder and it's held the time for 20 hours now.

Edit: you posted the reply saying you figured out the pinout as I was typing this message, sorry for the duplicate info

No worries. Better twice the info, than none. 😀 Plus yours is in textual form. Better to search for.

I use SAFT 3.6V 14500 lithium batteries with solder leads. I mount them on a small piece of raster board, put a diode in series to protect against charging and glue it neatly away from the motherboard with double sided 3M tape into the case. Since the RTC and CMOS take only microamps usually, it will last many years, probably decades...

dkarguth wrote:

Also, I believe that those batteries are supposed to be 3.6v, not 1.2. At least that's what mine was labeled as when I removed it.

Yes, I was mistaken. I am in the process of removing the battery. It is glued down with hot-melt-glue. Any ideas on how to remove it? Hot air station?

root42 wrote:

The 1MiB it has is good enough for DOS games and for Windows 3.1 I now have the 386DX.

While i haven't had precicely experience with Windows 3.1, I remember that Windows 3.11 didin't even boot with 4MB of ram back in days... With 6MB it was fine.

dkarguth wrote:

Yeah, your example is pretty nice. Totally not jealous. I got mine in its original case, a horizontal under-monitor type. It had an oak vga card, and a 40 mb seagate hdd. The power supply also had this stupid little .1 inch header socket wire that was on red/black wires for some reason. The HDD light cable was on a .1 inch header with red/black wires. Mistakes were made. Goodbye, seagate ST-157a.

These wires from PSU are for connecting the LED segment displays on the case…
Too bad about the ST-157A. These are mine favourite 40-45MB drives. Very reliable I recently purchased two of them. One looks and sound brand new (but of course been used). Other one sound a bit 'grinding' but works fine too… These drives have LED built in which can be deactived with jumper... I don't recall the pins for connecting external LED though… I prefer to connect HDD LED to controller board anyway.

root42 wrote:

dkarguth wrote:

Also, I believe that those batteries are supposed to be 3.6v, not 1.2. At least that's what mine was labeled as when I removed it.

Yes, I was mistaken. I am in the process of removing the battery. It is glued down with hot-melt-glue. Any ideas on how to remove it? Hot air station?

Better to use hot knife attachement for you soldering iron - if you have one...
But if the glue is old/hard enough just lightly pulling should unstick it from battery or motherboard...

HanJammer wrote:

root42 wrote:

dkarguth wrote:

Also, I believe that those batteries are supposed to be 3.6v, not 1.2. At least that's what mine was labeled as when I removed it.

Yes, I was mistaken. I am in the process of removing the battery. It is glued down with hot-melt-glue. Any ideas on how to remove it? Hot air station?

Better to use hot knife attachement for you soldering iron - if you have one...
But if the glue is old/hard enough just lightly pulling should unstick it from battery or motherboard...

Operation successful. Turns out the glue was a) old enough and b) the head from desoldering and wicking the leads was enough to melt it a little bit. Now off to clean the flux and glue residue.These boards are real beauties! I love them! For this I really would love a small desktop case. But they are so rare, crappy and still quite bulky...

Happy little motherboard...

HanJammer wrote:

These wires from PSU are for connecting the LED segment displays on the case…
Too bad about the ST-157A. These are mine favourite 40-45MB drives. Very reliable I recently purchased two of them. One looks and sound brand new (but of course been used). Other one sound a bit 'grinding' but works fine too… These drives have LED built in which can be deactived with jumper... I don't recall the pins for connecting external LED though… I prefer to connect HDD LED to controller board anyway.

That does make sense about the LED segment display. At the time I had never seen one of those before, and the case didn't have one. It must have been a generic AT style power supply. The entire computer was pretty generic, tbh. I ordered another ST-157a off ebay a couple of weeks ago. The drive itself is fine, but one of the chips on the controller got toasted. I'm just going to borrow the controller board to get my data off of the drive. I actually sourced a replacement for the original chip that I toasted, but it's like 20 dollars. I'm debating whether it's worth it and if my soldering skills are good enough to solder a QFP. Those drives have stepper-actuated heads, so they are very reliable drives. (and they sound cool too 😀 )
Unusually enough, the controller card did not have any kind of activity led header. The only spot to put it was on the drive.

root42 wrote:

Happy little motherboard...

I suppose that makes mine a sad little motherboard? 🤣

btw, any tricks to cleaning off that corrosion?

dkarguth wrote:

root42 wrote:

Happy little motherboard...

I suppose that makes mine a sad little motherboard? 🤣

btw, any tricks to cleaning off that corrosion?

Very carefully swab the corroded parts with pure household (clear) vinegar. I use this german household brand, but any 25% vinegar acid will work, bottle should be 1 EUR tops:

https://www.surig.de/produkte/essigessenz/

Clean off afterwards everything with plenty of isopropyl alcohol. I buy mine in the pharmacy, about 8 EUR per liter. And you need only relatively little for cleaning. Be careful -- it's flammable. Let it dry before doing anything else with it.

dkarguth wrote:

root42 wrote:

Happy little motherboard...

I suppose that makes mine a sad little motherboard? 🤣

btw, any tricks to cleaning off that corrosion?

Soak the corodded spot and 3-4 cm around with white vinegar and let it sit for couple of minutes. Do it on both sides of the motherboard. Scrub the corroded places with cotton pads or better - ESD brush. Heavy corossion on metal parts may require sanding with sand paper though.
Rinse the whole area or even whole motherboard with distilled water or isopropyl alcohol / PCB cleaner. Put it in dry and warm place and let it sit until dry.
Inspect the area - if you notice darker spots on traces under the solder mask - leave them be (but you are risking the corrosion will break them eventually) or clean the spots with really mild sandpaper (1600 grit or more) and when clean - apply new solder mask or some kind of enamel (can be tamiya acrylic or other hobby enamel). I usually don't bother cleaning these darker spots immediately - if motherboard stops working I will know where to look for dammage and I will need to remove solder mask and fix the trace anyway...

Thanks! Will try once I can bring myself to completely disassemble the PC for the 8th time this week.