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Alaris Tornado 2 VIP 486 Motherboard VRM(?) Issues

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First post, by WJG6260

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Hello everyone,

I recently came across an Alaris Tornado 2 VIP board. Unfortunately, my photos of the board are too big to host natively, so here's an imgur link with a bunch of higher-res photos of what we're dealing with.

It's quite the interesting one, being made by the same Alaris that made the Leopard SLC2 boards and Cougar BL3 boards. It's pretty nicely-equipped, with an Efar Chipset (I think it's an SiS 471 clone, based on what I see on UltimateRetro) and OPTi 822 VLB-PCI bridge.

However, the dang thing just won't boot. I noticed, upon probing with a multimeter, that the voltage on the Vcc pins of the CPU socket was all over the place, wobbling between ~2.2-3.4V. Probing the ISA slots, I confirmed that the board is getting good 12V and 5V power from my ATX PSU. The ISA bus was operating at 6.3MHz, per my oscilloscope, and the 14.3MHz reference clock was good. My POST card showed no signs of life, and the board didn't want to boot no matter what I did. It came with a Cyrix DX2-v80, which is indeed good, but won't boot with any jumper configuration or tinkering.

I replaced the linear regulator MOSFET with an equivalent, known-good part and replaced the two electrolytics near the MOSFET, as they showed quite high ESR and were otherwise out of spec. The voltage issues improved somewhat, but the voltage is still somewhat inconsistent, hovering between 2.8-3.3V. The MOSFET is being fed a good 5V (really 4.9ish).

Unfortunately, I have no idea how the heck to set the jumpers on this thing and there's nothing on this board on UltimateRetro. The Alaris Leopard VX, a non-VIP variant of this board, exists there, but has a totally different layout in terms of jumper blocks. I can't figure out how to get the CPU voltage to change, so any help there would be greatly appreciated.

I noticed that a few of the SMD components near the VRM setup seemed...suspect, so I probed around some more with a multimeter and noticed that the LT1431 (seems to be an adjustable voltage shunt regulator) is getting a full 5V at its cathode pin; weirdly, it is not displaying the proper 2.5V on the reference pin. In reality, that reading fluctuated between 1.8 and 2.2V, staying mostly around 2.2V but bouncing around heavily. I suspect some bad SMD components may be at issue here and I'm not sure but I think that it's R22 in the VRM close-up photo that's at issue because the voltage is 5V on one side and the same ~1.8-2.2V on the other that the reference pin of the LT1431 showed. In fact, the two are in continuity, as per my multimeter.

So, does anyone have any thoughts on how I ought to proceed? Do I need to replace this one particular SMD resistor, or could there be something else going on here? Has anyone experienced anything similar?

I'd love to hear your all's thoughts. Thank you in advance for your input!

-Live Long and Prosper-

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Reply 1 of 3, by mat919

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WJG6260 wrote on 2022-02-04, 00:50:

Hello everyone,

....

I'd love to hear your all's thoughts. Thank you in advance for your input!

Any luck with jumper settings? I cannot find any documents about this board... not to mention drivers.

Reply 2 of 3, by bracecomputerlab

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Just my subjective opinion, but US built mainboards appear to use "nicer" components than most Taiwan produced mainboards of that era.
There are Linear Technology (LT) components on this Alaris mainboard.
Linear Technology stuff tends to be rather expensive since I have purchased 4 different Linear Technology components for my VIA and Intel reference schematic mainboard replica project.
It is unfortunate that Alaris could not survive as a firm (part of the deindustrialization of America due to free trade agreements like NAFTA).
They supposedly produced them in Fremont, CA off of Interstate I-880 in the 1990s, I am told.

I think the EFAR chipset here is a rebadged version of the 486 era OPTi chipset.
Maybe they did not bother with it for the VLB to PCI bridge.

Reply 3 of 3, by mat919

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Hi all.

I purchased the Alaris Tornado 2 motherboard many years ago. It came with no manual and to my disappointment no settings were printed on the board itself. It booted and reported 486DX2-66 CPU. Small profile radiator was glued to the CPU and no fan was included.

The "original" jumper settings that came with the board and were:

JP5

1-2 closed
3-4 opened
5-6 opened

JP22

1-2 closed
3-4 opened
5-6 closed

JP1

All A-B closed

JP23

No jumper (All opened)

At some point I replaced the CPU with i486DX4-100 and it worked with no jumper changes.

Occasionally the system would freeze though for no apparent reason when either processor was installed. I suspected something was not set correctly, but I didn't have time, knowledge or documentation to investigate it further.

I also tried Am486DX4-120, but it did not work with the same jumpers.

Recently I realized someone posted jumper settings for the board (finally), but some of them are wrong (A-B-C instead on 1-2-3 on Jumper JP1) or do not apply to my revision of the board?

https://theretroweb.com/motherboard/manual/to … fc531907298.pdf
https://theretroweb.com/motherboards/s/alaris-tornado-2

I dusted it off and fire it up to play little with it but I got even more confused.

After I removed the radiator I realized it was overclocked i486DX2-50 installed not DX2-66. I also realized i486DX4-100 supposed to run on 3.3V not 5V, but nothing major happened.

According to the posted settings I switched jumper JP5 to 3.5V and JP12 to 3.3V left jumpers JP1 untouched to 1-2 (I think should be A-B) and dropped DX4-100.
Computer booted and reported 486WB-100, but when I switched JP1 to 2-3 (B-C), BIOS reported 486DX4-100.

The processor is actually EW variant, which means JP1 was at the correct setting the first time around, therefore JP1 might not be for multiplier but for Write Back Write Through cache? I have no idea.

I would like to use AMD 120MHz eventually but I would need some help from more experienced users. For some reason I love this board and I don't want to ruin it completely.

First of all, I want to pinpoint what might have caused the motherboard to hang sometimes.

Was it:
A) improper jumper settings for DX2-66 CPU (overclocked DX2-50)
B) insufficient CPU cooling
C) dying battery (since I got once or twice "malfunctioning battery" message.
D) JP23 function

Do you own this board? What are your settings and for which CPU? Do you know how to correctly install Am486DX4-120?

Come on people, let's figure this motherboard out! We can help preserve history and increase the value of this piece of hardware.

Thanks.

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