Ydee wrote on 2021-09-17, 14:06:

I'm afraid I can't help you with advice, my board is an older version of HOT 419 with the same chipset, but with a slightly modified configuration. But the configuration for the FSB is the same, and I noticed it's set to 50 MHz on your photo, which is why I wrote to you. The jumper settings table is correct, but the jumper numbers are jumbled, so it can lead to a mistake if a person is inattentive. For AM486DX4-120, the FSB should be set to 40 MHz (yellow indicated in my photo above).

I have seen this board before. I will check the HOT 419 manual. Maybe I'll learn something there.

Ydee wrote on 2021-09-17, 14:06:

I cleared the CMOS by removing the connection on the jumper for the external battery (my board had a onboard NiCD battery), you can just take out CR2032. I think you can erase the CMOS by removing the link from the J1 jumper above the DIN keyboard connector - so I had it with me.

I did that. Did not help. I'll try all suggestions once I have new PSU. Thanks.

snufkin wrote on 2021-09-17, 13:52:

I think the 'B' type resistor networks are in pairs (so 1&2, 3&4, 5&6, 7&8), and the '0' means zero ohms. So I think those blocks are effectively just jumpers. I'd guess from the silkscreen that JPB and JPC select between Intel (pins 3-10 of JPB), AMD (pins 1-8 of JPB) and Cyrix (pins 3-10, the only ones with header pins, of JPC). The move JPA to set the 486 type. But I don't know which settings would be right for an Am486DX4.

Have you got a multimeter you can use to check what voltage is going to the CPU?

I think you are right about that. The manual shows jumpers not present on the board. Instead, there are resistor networks where jumpers JP3, Jp5 and Jp8 should have been. Similar goes for JP42, JP43 and JP44. I'm getting a headache just trying to figure it out.

I do have a multimeter, but where (which pins) would I check the voltage going to the CPU? (once I have a working PSU again)

Ydee wrote on 2021-09-17, 14:06:

I'm afraid I can't help you with advice, my board is an older version of HOT 419 with the same chipset, but with a slightly modified configuration.

Well... thanks to your input the confusion is over. I looked up HOT 419 motherboard and it turns out that there is an error on www.win3x.org website. Pictures of the motherboards we discussed are SWAPPED!!!
Check it out. Jumper settings drawing and picture don't match.
This is Forcom Technologies 419:

http://www.win3x.org/uh19/motherboards/2495

but has a picture of Shuttle HOT 419 .

This is Shuttle HOT 419:

http://www.win3x.org/uh19/motherboards/4439

but has a picture of Forcom 419 .

Since your motherboard has 72-pin memory slots you, my friend, might have Forcom Technologies 419 "R" model as shown here:

http://www.win3x.org/uh19/motherboards/2496 .

Tell me what you think.

At least now I have detailed and ACTUAL user manual for my board. Once I have working PSU maybe (hopefully and finally), I might be able to make it work again.
Thank you for your suggestions.

mat919 wrote on 2021-09-18, 15:08:

Since your motherboard has 72-pin memory slots you, my friend, might have Forcom Technologies 419 "R" model as shown here:
http://www.win3x.org/uh19/motherboards/2496 .
Tell me what you think.

Thank you for your investigation, it's interesting, but I don't know if it's that simple. Shuttle HOT-419 versions and revisions were numerous, and I spent a lot of time looking for exactly what version I have. I was only partially successful - based on BIOS ID I end up with two versions, namely RZ or R1. I based my data on http://www.plasma-online.de/index.html?conten … ard/mb_hot.html.
The data for the Forcom 419R board mentions the dual Vcore 3,3/5V option and it is missing from my board - it does not have a voltage regulator. Also some jumpers are placed in other positions although otherwise it is very similar and I think it is an OEM version of Shuttle HOT 419 plates, sold under the brand name Forcom.

Ydee wrote on 2021-09-19, 10:29:

Thank you for your investigation, it's interesting, but I don't know if it's that simple (...) and I think it is an OEM version of Shuttle HOT 419 plates, sold under the brand name Forcom.

Obviously you did your homework well and you know much more about your board than I do. I wasn't even aware about the BIOS string ID website you mentioned in your post.
Based on the User Manual, I am almost 100% positive that Shuttle HOT 419 is what I have, and once I hopefully revive my 419, we'll see to what revision of the board the BIOS strings are matched to.
Meanwhile..., thank you for all your help.