Very nice little board, albeit a little dirty. Your VGA card is 8-bit or set to 8-bit already I guess? There is a DIP switch on your XT (SW-A, the red one), try setting the monitor selection to other settings (SW-A/5&6, on-on, off-on, on-off) instead of monochrome (off-off). Your board looks like this one on TH99 btw.

kalohimal wrote on 2020-07-14, 04:56:

Very nice little board, albeit a little dirty. Your VGA card is 8-bit or set to 8-bit already I guess? There is a DIP switch on your XT (SW-A, the red one), try setting the monitor selection to other settings (SW-A/5&6, on-on, off-on, on-off) instead of monochrome (off-off). Your board looks like this one on TH99 btw.

Yeah needs a proper cleanup 😀

VGA card is not 8 bit per se, and I haven't really set it to anything but it works as is on XT (worling fine on another board just like this one)

The link you sent is the same one I was going by. Tried the monitor.combinations and nothing changes (curiosuly, I had forgotten to check this on the working board and that one boots.just fime despite having been set to monocrome...)

I would first hazard to guess that there is one RAM IC missing. There are 8, but usually you have 9 ICs in a bank, for parity. But maybe it also runs without parity. But it will not hurt putting a 9th RAM IC there. Also, I see one 640032C IC, which is probably BIOS? But below there is an empty socket. Maybe half the BIOS is missing?

Looks like a Juko board. Those can usually work without parity by setting a jumper.
Is the CPU an 8088, v20, 8086 or V30?

Soldered V20? Wow.

Anonymous Coward wrote on 2020-07-14, 08:27:

Looks like a Juko board. Those can usually work without parity by setting a jumper.
Is the CPU an 8088, v20, 8086 or V30?

It's a NEC, so probably V20 or V30. What do you say regarding the empty ROM socket? Is it probable that all the BIOS is in that one ROM, or is one missing?

Found a very similar Juko board, as hinted by Anonymous Coward:

http://www.funkygoods.com/mb/juko/juko.htm

That one also has only on BIOS ROM IC. So probably all components are there. Maybe try a POST card to see if it gives any hint of what's wrong?

NEC also made regular 8088 you know ? ^^

Can you switch the Keyboard LEDs when its on? I also assume a Video configuration Problem. A Post card will not help on XT. You need to program a diagnostic Rom for further analysis..

Deksor wrote on 2020-07-14, 11:43:

NEC also made regular 8088 you know ? ^^

No, that's actually new to me! Fascinating! But this being a late Turbo XT board, I would bet this is a V20!

root42 wrote on 2020-07-14, 07:45:

I would first hazard to guess that there is one RAM IC missing. There are 8, but usually you have 9 ICs in a bank, for parity. But maybe it also runs without parity. But it will not hurt putting a 9th RAM IC there. Also, I see one 640032C IC, which is probably BIOS? But below there is an empty socket. Maybe half the BIOS is missing?

Yes, it runs without parity as well, and one of the switches is in fact to set if you use parity or not.

The other board I have which works fine, has the same ram configuration and amount of chips for a total of 1MB.

Anonymous Coward wrote on 2020-07-14, 08:27:

Looks like a Juko board. Those can usually work without parity by setting a jumper.
Is the CPU an 8088, v20, 8086 or V30?

This one has a V20 (soldered 🙁 )

Well if you have a v20 the fact it's soldered isn't that bad because it's pretty much the fastest CPU of the platform

Predator99 wrote on 2020-07-14, 11:49:

Can you switch the Keyboard LEDs when its on? I also assume a Video configuration Problem. A Post card will not help on XT. You need to program a diagnostic Rom for further analysis..

Yep. Keyboard lights are a go, on off, etc.

The empty ROM socket is to add ROM BASIC.

Since the board has a V20, it's probably the Juko ST (Super Turbo?).
I have a very similar board with a V30, and it's the Juke NEST. (New Enhanced ST?)

walterg74 wrote on 2020-07-14, 15:33:

Predator99 wrote on 2020-07-14, 11:49:

Can you switch the Keyboard LEDs when its on? I also assume a Video configuration Problem. A Post card will not help on XT. You need to program a diagnostic Rom for further analysis..

Yep. Keyboard lights are a go, on off, etc.

Then the board seems to be OK and up. Only problem is you dont see anything. Its the video card (or very unlikely a problem with the ISA bus). Try another VGA or better MDA or CGA...

Try all the ISA slots and clean the VGA card's edge with an eraser too. The ISA slots on this board looks rather rusty, some of the connecting pins look corroded with green/white color stuffs.

Tried all that but no go. The board gives out a single beep as expected with normal boot but image never appears.

Will try to get a monochrome monitor, since mda cards I have 3 but not a monitor.