I can find 3 different elt-286b boards on stason. This one resembles a little to yours : http://stason.org/TULARC/pc/motherboards/U/UN … -160B-120B.html . However all of them have the same name for each jumper, and I don't see many of them. If there are other jumpers on yours, try to experiment. And the 286s get really hot,indeed!

http://stason.org/TULARC/pc/motherboards/U/UN … -160B-120B.html

looks REAL close to the one you have, but sadly looks pretty sparse on the information. 🙁

also, the only caps that "go bad" are the aluminum can style. Not saying that other caps CAN'T go bad its just 99% of the time its the silver cans.

also, the only caps that "go bad" are the aluminum can style. Not saying that other caps CAN'T go bad its just 99% of the time its the silver cans.

Well, those tantalum ones do go bad sometimes, but there's usually no doubt when it happens... they tend to go out with a bang. Literally. If they all seem intact, it's probably safe to leave 'em alone.

Cool thanks for that. Unfortunately the board on stason isn't quite the same - the jumper numbers are different.
I assume JP18 is keylock and power LED, and perhaps either JP26 and JP30 is turbo LED but then I'm not sure what that LED1 is meant for. I guess one of JP30 and JP26 could be reset.

Any thing else I can try to stop the rebooting problem?

you mention that you have been playing with the jumpers, is it possible that you are overclocking the processor?

I doubt it, the only jumper I fiddled with that I'm not certain of is J25 and the problem occurs in both positions.

What does that 'CPU Speed' option in the BIOS do? I assume that just sets wait states/timings or something?

The CPU speed is probably for setting the default turbo state on/off. High would be 10mhz, low is probably 8 or 6 or something.

makes sense I guess. The board has a 16MHz and a 20MHz crystal on it, so I assume it could run the CPU at either 8 or 10MHz.

Old Thrashbarg wrote:

also, the only caps that "go bad" are the aluminum can style. Not saying that other caps CAN'T go bad its just 99% of the time its the silver cans.

Well, those tantalum ones do go bad sometimes, but there's usually no doubt when it happens... they tend to go out with a bang. Literally. If they all seem intact, it's probably safe to leave 'em alone.

Yup, had it happen once. Sounded like a damned firecracker all of a sudden! I can tell you, I was wiiide awake in an instant!

I remember once I got a 386/40 board that had some great deal of damage from battery fluids. One of those capacitors, that are close to the AT power connector, went off with a bang and a flame as soon as I powered it up. The funny thing though, is that the board is working fine....

I have made some progress on this 😀

I managed to track down an EGA monitor and video card 😁 The monitor is an ECM-5400.

Pulled out the VGA adapter and set up the EGA adapter/monitor.
Now the rebooting problem seems to have resolved itself?
Seems very strange, I tried 3 different 16-bit VGA cards and they all showed the same issues - a Trident, an Oak and an ET4000. I can only assume some sort of incompatibility with VGA on this board. Or perhaps the EGA card is less of an electrical load on the motherboards chipset and bus.

Anyway, hopefully it stays fixed with the EGA card.

After some experimentation I think I have discovered the jumper settings. J30 seems to be reset (at least, it restarts if I short it with a screwdriver...) while J26 seems to be Turbo. Using Sysinfo's CPU benchmark the score drops from 7.6 to about 5.2 if this jumper is enabled/disabled.
J25 seems to be enable/disable CPU speed select via keyboard. With this jumper set 1-2 I can use ctrl+alt and +/- to increase or decrease speed. Sysinfo actually reports that the CPU changes from 10MHz to 8MHz using this key combo with a drop in the benchmark score to about 6.0. If J26 is set 2-3, this keyboard combo doesn't have any effect- CPU stays at 10MHz and score doesn't drop.

so thanks for the assistance, hopefully I've got everything sorted now 😀

Long shot, but is it possible you need to set a jumper on the motherboard for EGA or VGA?

Dunno, there's a jumper labeled MONO and I've set it to 2-3 (away from MONO). No other jumpers that I can find that haven't been discussed.

The system doesn't need to know if its an EGA or VGA.

Maybe your power supply is weak?

That's certainly a possibility. Its a 230W AT. Of course its pretty old now, visually it appears fine internally and all voltages are within 5% tolerance with a multimeter but nothing is certain with this old hardware...

DonutKing, how is your 286 project coming along? I have got my very first 286 mobo on its way in the post, and I am looking forward to seeing what it can do. Unfortunately, I don't have any EGA (or CGA or monochrome) video cards, and I don't have any CRT either (just an LCD), but I'm hoping that a 16-bit VGA ISA card will work OK with it.

Well I've hit a couple of stumbling blocks. The case I was going to use seems to have no threads to screw in the motherboard standoffs- it just has holes with no thread, about 3-4mm in diameter.

So I bought some nuts to try screwing on the underside of the standoffs but then I found that the expansion card slots in this case are about double the distance from the bottom of the case as all my other cases - so when the motherboard is mounted in the case, I can't install any expansion cards because they physically don't reach the slot. So I've been trying to find some sort of mounts that are double the height of standard motherboard standoffs.

Apart from that though its pretty much ready to go, I've swapped to a different motherboard with a 12MHz 286 CPU and an 8MHz 287. Other parts include an EGA video card and monitor (was VERY lucky to track down the monitor, turns out a bloke I knew on another forum that was into ham radio had a stash of old goodies) as well as a 40MB ST251 MFM hard disk and controller, a 1.5MB Intel 'Above Board' Expanded Memory card, and a 1987 Adlib 😀

I've sort of left this on the backburner for now but hopefully I'll find some sort of mounting solution and get it rolling again. I've also picked up an Amiga 500 and a box chock full of floppies for it which I've got to have a fiddle with.

Well I've hit a couple of stumbling blocks. The case I was going to use seems to have no threads to screw in the motherboard standoffs- it just has holes with no thread, about 3-4mm in diameter.

That sounds like the old style AT standoffs... they'd usually use one or two screws, and the rest were plastic standoffs that just slipped into slots on the motherboard tray.

This has given me an idea. Is it possible to buy any ATX PC case, and drill your own holes in to its base area, and then push these plastic standoffs in to them, so it can hold an AT mobo in place? I mean, the drilling precision required for the holes wouldn't be too high I guess, because there is no "screw thread" involved when you insert the standoffs.