For the expansion cards - with this board you really need to FORCE them in. Especially if that port has not had any in it for a while. I really sometimes had to use so much force i thought it's gonna break. If you have a case where you can remove the second side cover then give it some support with the other hand while you squeeze in the card to make sure it wont break in the middle. The CR2032 battery for the bios is worth the 50 cents on ebay or so.

If I can see well, there isn't a socket for a 2032 battery, but a circle indicating where such a socket would be placed. I bet that originally it had a barrel type battery soldered there.It must also have an external battery connector.
If you're going to change the cpu, check the crystal. If it has a 20MHz right now, you're going to need a 32MHz for a 16MHz cpu.

Thank both, iam also thought that i maybe could look for a old ISA card that iam not going to use anymore and put the card in several time on each slot and hoping the it would be easier to acces the expension slot.

About the battery coin header.. Yes there where actually have been a coin holder on that place.. It seems that is solderd off, i think because of a battery leakage.. The board is in good shape, but the header for the external battery has a little bit oxydation on it (little bit green from the battery)

Iam also having a problem with the diags of the bios..
It says: ROM-DIAGS cant be loaded
Check BIOS-ROM TYPE!

The IC roms are from: OKI M27256ZB - 7x3050.

I dont think these arent the orginals. Normally there would be a EPROM with quartz class in.. This one hasnt one.. And i think this IC could be programmed once.. The same like my NEC T128 SCSI adapter card..

SO i could try different kind of IC chips. Or the ICs are in the wrong socket..

EVEN was in the ROM-1 socket
ODD was in the ROM-3 socket.

And there is also socket ROM-0 and ROM-2

So maybe i could try EVEN in ROM-0 socket and ODD in ROM-1 socket.
The 4 sockets can made use of 27128 and 27256 rom types..

And about the crystal, i dont see anything like socketed crystals.. Maybe its handled by one of those IC PLCC chips..

I told you I've got the same board on another thread. I took a look at it later and found out that it is similar, yet not the same. Mine has more memory sockets. But the layout is very similar. I encountered the same problem concerning the BIOS once, and it turned out to be one of the dip switches that was at the wrong position. There's a selection for 27128/27256. I changed it and it worked. However I had some problems with the memory. Even when I found which one of the memory chips was faulty, it gave me a parity error. So I tried something else. I replaced the BIOS chips with 2 other I had from a newer 286 that had gone bad, and it works perfectly.

About the crystal, on mine it isn't socketed but soldered on to the board. Seems to me, those days they made the boards for a fixed speed that would never change. Also I remember on your V20 thread, you mentioned that you bought a suntac 286-12 board. If that's the case, it may be running at 12MHz, and the 10MHz cpu is kind of overclocked.

He, i already tried that with bios selection 27128 / 27256. I tried both an got the same message:

It says: ROM-DIAGS cant be loaded
Check BIOS-ROM TYPE!

Iam also tried to get the ICs out and fitt them again, but no solution yet.
My memory chips where all ok. I have tested them with a program called checkit. And there where no errors in the memory.

And where can i find those crystals?

Have your bios the working Diagnostics onboard? And whats the brand of your roms? Mine uses a AMI bios..

I've been looking for crystals about half a year ago. I needed a 40Mhz for my other 286 which was upgraded from a siemens 286-16 to a Harris 286-20, and a 50MHz one to test a 386-25. I found on ebay,

My original BIOS didn't have diagnostics. But that was the one that didn't work. The other I use now is newer and has the Diags option after you press the DEL key. Both of them are from AMI. (To be honest, I wouldn't like any other brand. My original 286 bought in 1991 had the same AMI BIOS with the Diagnostics, and I like that a lot 😀 )

Robin4 wrote:

The board is in good shape, but the header for the external battery has a little bit oxydation on it (little bit green from the battery).

As a precaution, you should neutralise that corrosion with some vinegar, then clean with isopropyl alcohol or acetone.

Amigakit has a good range of crystals:
http://amigakit.leamancomputing.com/catalog/i … ex.php?cPath=45

I just thought I'd go ahead and warn you about some of risks of swapping in a CPU and crystal. First of all, this is an early VLSI board. Early VLSI chips were notorious for failing, which is why they are usually socketted. An easy way to kill those chips is to run them at speeds they were not designed for. Most of the time these chips have a maximum frequency stamped into them, so you might want to check and see what they say.
Secondly, many of the 10MHz 286 systems ran the ISA bus at the same speed as the CPU (some 12MHz 286s did too, which was a big no no). If you have such a board, you are going to have serious trouble running your ISA cards at 16MHz. Most of the boards that supported ISA bus dividers had a jumper on the motherboard, but sometimes it's in the BIOS like on 386/486 systems. Also be away you might be overclocking other things too, like the DMA controllers.