ChelonianEgghead wrote on 2022-04-08, 20:11:

Hi guys! So I recently decided to try building a 486 because the early 90's were just such a fascinating era in computing history, and while this is my first time actually building a PC from scratch I'm pretty familiar with how most stuff goes together. However when I tried to power it on by shorting the green and black wire from the ATX to AT adapter nothing much happened except the power LED on my IDE SD card reader turned on and the PSU started squealing and its fan turned on. Not even so much as an error beep from the speaker. There is a scratch on the motherboard across some of the traces by the bottom left motherboard screw but it appears to be only cosmetic and doesn't even show up in the picture. I made sure my jumper settings for the CPU are correct according to the motherboard manual, though I'm not so sure about the memory, and I tried putting the speaker in both ways because I'm not sure which one is right, but none of that seems to help. Other than that I don't know how to troubleshoot it, any ideas?

It's got an Edom International 486VL3 motherboard, a Cyrix 486Dx2 CPU @66Mhz, two 8MB sticks of FPM SIMM RAM, a Winbond Kaos VL400GW IDE controller (if someone could help me find the manual that would be much appreciated), Cirrus Logic GD5428 VGA card, ESS AudioDrive 1688F sound card, some SD card adapter from eBay and a 512 MB SD card, and an EVGA 400W ATX power supply with an adapter. Here's some info on the motherboard if that helps. And here's a less compressed version of the attached image. Looking forward to your replies, and thanks for your time!

Does the CPU get warm?
Is it a 5v or a 3.3V CPU? I guess 5V, right?

A POST card (diagnostics card) would be really helpful here.
Some models not only show the BIOS codes, but have extra LEDs that show the presence of voltage on the ISA pins for 12v, -12v, 5v, -5v.

ChelonianEgghead wrote on 2022-04-08, 20:11:

Hi guys! So I recently decided to try building a 486 because the early 90's were just such a fascinating era in computing history, and while this is my first time actually building a PC from scratch I'm pretty familiar with how most stuff goes together. However when I tried to power it on by shorting the green and black wire from the ATX to AT adapter nothing much happened except the power LED on my IDE SD card reader turned on and the PSU started squealing and its fan turned on. Not even so much as an error beep from the speaker. There is a scratch on the motherboard across some of the traces by the bottom left motherboard screw but it appears to be only cosmetic and doesn't even show up in the picture. I made sure my jumper settings for the CPU are correct according to the motherboard manual, though I'm not so sure about the memory, and I tried putting the speaker in both ways because I'm not sure which one is right, but none of that seems to help. Other than that I don't know how to troubleshoot it, any ideas?

It's got an Edom In++ternational 486VL3 motherboard, a Cyrix 486Dx2 CPU @66Mhz, two 8MB sticks of FPM SIMM RAM, a Winbond Kaos VL400GW IDE controller (if someone could help me find the manual that would be much appreciated), Cirrus Logic GD5428 VGA card, ESS AudioDrive 1688F sound card, some SD card adapter from eBay and a 512 MB SD card, and an EVGA 400W ATX power supply with an adapter. Here's some info on the motherboard if that helps. And here's a less compressed version of the attached image. Looking forward to your replies, and thanks for your time!

Hi, have you made sure the pins for IDE cable are correct?
I remember once plugging the cable for my HDD the wrong way and the motherboard didn't show any signs of life.
I fixed the cable and the motherboard showed POST, audio beep and the ram counting, then booted correctly, even without the on board battery (486 with former barrel battery).
You might be needing an external battery as some MBs won't even POST without it.
Try to see if without the IDE HDD connected the MB goes to POST.
This is where i've found more detailed info about your MB.
https://www.elhvb.com/webhq/models/486pci/mp032.txt.html
The external battery is J2 (4 pin near onboard battery) 1 for + and 4 for -.
Edit: i might have found your controller specs.
Edit2: I've looked images online and they don't match.

CoffeeOne wrote on 2022-04-08, 21:31:

ChelonianEgghead wrote on 2022-04-08, 20:11:

Hi guys! So I recently decided to try building a 486...

Does the CPU get warm?
Is it a 5v or a 3.3V CPU? I guess 5V, right?

Yes, I just measured it with an infrared thermometer and it started heating up immediately on receiving power. I don't know what voltage it is, I'll try removing the heatsink tomorrow to see if it's printed on the top, but I can't find any information about it online. The seller listed it as a H1LP530C but it has "A3LM449AJ"printed on the bottom.

Jo22 wrote on 2022-04-09, 06:00:

A POST card (diagnostics card) would be really helpful here.
Some models not only show the BIOS codes, but have extra LEDs that show the presence of voltage on the ISA pins for 12v, -12v, 5v, -5v.

Didn't know those were a thing, that's awesome! Should have one coming next week so if I haven't got it running by then I'll let you know what code it displays.

Luke4838P wrote on 2022-04-09, 12:16:

Hi, have you made sure the pins for IDE cable are correct? I remember once plugging the cable for my HDD the wrong way and the m […]
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ChelonianEgghead wrote on 2022-04-08, 20:11:

Hi guys! So I recently decided to try building a 486...

Hi, have you made sure the pins for IDE cable are correct?
I remember once plugging the cable for my HDD the wrong way and the motherboard didn't show any signs of life.
I fixed the cable and the motherboard showed POST, audio beep and the ram counting, then booted correctly, even without the on board battery (486 with former barrel battery).
You might be needing an external battery as some MBs won't even POST without it.
Try to see if without the IDE HDD connected the MB goes to POST.
This is where i've found more detailed info about your MB.
https://www.elhvb.com/webhq/models/486pci/mp032.txt.html
The external battery is J2 (4 pin near onboard battery) 1 for + and 4 for -.
Edit: i might have found your controller specs.
Edit2: I've looked images online and they don't match.

Just tried reversing the IDE cable, no dice. I'll try getting a battery for it, thanks for the tip. However I did notice that when I forgot to plug the CPU back in I didn't get those weird high pitched squeaking noises so it could be an issue with voltage settings as CoffeeOne suggested. How (un)safe is it to mess around with the voltage settings of an unknown CPU? Or should I just buy some more thermal paste and remove the heatsink to find out for sure?

In general, the moment the system does not boot and you have no prior knowledge of it's state:
1st thing, reduce entities, possible causes of malfunction.
Meaning:
Take it out of the case and suspend it safely on some clean, ESD-safe surface.

Strip it. No RAM module, no cards, no devices.
(That would have the additional benefit that you could make a photo of the whole board and others might notice some error or rogue jumper...)
Just a speaker known to work and on definitely the right headers. (polarity doesn't matter.)

Check it optically for damage and check the jumper settings again.

The speaker does about as much as the aforementioned diagnostic card, sometimes.
Meaning, if it goes beep or rather beep-beepedy-beepedeeboop, look up "phoenix beep codes" for your bios, proceed with RAM, etc.

If it doesn't even beep, then it's some kind of fucked.
Or the PSU.

Testing PSU: Hook it up dry with a HDD as miminal load and test all pins of the AT plug for the correct voltage.

PSU is an ATX with adapter - make sure that isn't shaky somewhere. Contact spray can help.

Some cards need the -5 V that ATX units don't offer. Maybe some mobos as well. Then you'd need an active adapter or an AT PSU.

BTW., if you get it to work - by setup, features and chipset, that is a really rare and nice motherboard.
Consider getting a faster chip like the amd p75 133 MHz to use more if its potential.

Pretty strange though to see a PCI board without onboard controller.
Compared to PCI, VLB parts are usually more trouble than joy. Consider going with PCI with anything but sound. Plenty of time experimenting with VLB boards without PCI.
VLB on VIP boards like this one was merely a legacy feature for people with really expensive cards from earlier VLB systems.
Might even be possible to deactive the VLB part in the bios.

btw., you'll have to check _all_ the jumpers in the manual, not just the basics for the CPU like with later systems.
e.g. on boards with migratory background, sometimes parts got cannibalized like the sram cache chips. So the board would still work but you need the correct settings for the remaining cache.

CPU:
http://www.cpu-galerie.de/html/cyrix486-cx486 … 2-66gp-086.html
So, pretty sure it only came in 5 V and you'll have to use the various settings that say "CX486M7" in the stason manual.
And those for "66i" speed, I'd say.

"VESA WAIT STATE CONFIGURATION ": Won't matter without cards, but later: 1 wait state is the safe setting

"BUS SPEED CONFIGURATION" Not quite sure any more what it does. 33 MHz might actually refer to the FSB speed - same as the CPU speed before the DX2. Setting it to ">33" may only be necessary for FSB above 33 and slow down the system, but could not hurt to get it to boot.

"PCI TRIGGER CONFIGURATION"
afaik, "level" is the default safe setting, "edge" the tweak.

Somewhat better PDF manuals here, I think:
https://www.ultimateretro.net/en/motherboards/2041

Ok, thanks for all the info. And yeah even luckier I bought it from a Ukrainian seller who had a whole bunch of them for cheap a few weeks before Russia started threatening to invade, hope he's alright, but he hasn't sold anything since Jan 26th it looks like. I'm not really looking forward to re-seating my Very Long Boards 🤣 because I always feel like I'm about to break them, but we'll see how it goes. I'll also double-check the other jumper settings, but it might be a few days before I have the time. And yeah I've got a battery holder coming next week, so hopefully that helps.

Also the ATX PSU is brand new so I'll check it to be sure but it should be fine.

ChelonianEgghead wrote on 2022-04-09, 19:42:

Also the ATX PSU is brand new so I'll check it to be sure but it should be fine.

As I wrote - check it with the adapter on the AT end, since that's what counts.

VLB cards are weird, but robust 😉

Cuttoon wrote on 2022-04-09, 19:46:

ChelonianEgghead wrote on 2022-04-09, 19:42:

Also the ATX PSU is brand new so I'll check it to be sure but it should be fine.

As I wrote - check it with the adapter on the AT end, since that's what counts.

VLB cards are weird, but robust 😉

Are you sure they are robust? They seem rather fragile to me compared to contemporary ISA and PCI cards.

Tetrium wrote on 2022-04-09, 23:54:

Cuttoon wrote on 2022-04-09, 19:46:

ChelonianEgghead wrote on 2022-04-09, 19:42:

Also the ATX PSU is brand new so I'll check it to be sure but it should be fine.

As I wrote - check it with the adapter on the AT end, since that's what counts.

VLB cards are weird, but robust 😉

Are you sure they are robust? They seem rather fragile to me compared to contemporary ISA and PCI cards.

Well, robust is relative. I transplanted an old DX2-80 board with Miro Crystal 10SD and E-IDE controller to my mom's desktop to upgrade a 386-40. In 1997 😜
(It probably was the slowest DX2-80 known to man, yet still a step up)
It survived my handling and back then, I was an impatient teen who didn't know shit and was not too gentle with obsolete hardware.
So, I can vouch for at least two VLB cards to take quite some punishment.
(They're still somewhere on the heap)

Of course, the length of the slot is a mechanical nightmare. One has to wiggle them out bit by bit, in order not to flex them.

Alright I got something! So apparently it's a memory issue, when I don't have memory installed or when I only have a stick in bank 2 it beeps 1-3-4-1 with no video output or anything. It still doesn't do anything if there's one in bank 1 or both are installed. I tried messing with JP45 but that didn't do anything, though at least now I know what the problem is.

Jo22 wrote on 2022-04-09, 06:00:

A POST card (diagnostics card) would be really helpful here.
Some models not only show the BIOS codes, but have extra LEDs that show the presence of voltage on the ISA pins for 12v, -12v, 5v, -5v.

Nothing comes up on the seven segment LED display, but the LEDs for +12v, +5v, CLK, IRDY, FRAME, and RESET all come on with -12v and +3.3v off for some reason. I also don't get any beeps with the card plugged in.

Unseated all expansion cards to no avail but here's the bare motherboard.

How sure are you that CPU is actually OK? Additionally when I test new motherboard I first power it on without anything connected. Just to wires into CPU socket to pins that are Vcc and GND to see what it actually sends to CPU. Just to be on the safe side...

Also, did you plug diagnostics card into PCI or ISA slot? You have to be careful of orientation if you plug it into ISA slot. On my there is marking "rear" on one side of the ISA slot. That's actually means rear of the case, not ISA slot. Card is not oriented the same way up when connected to ISA slot vs when connected to PCI slot.
If you plugged it into ISA oriented wrong that might be the reason why it only lights LEDs, mine did the same thing before I figured this out. Luckily nothing burned out, I've read that some people fried their motherboard with diagnostics card connected wrong in ISA slot 😬.

Oh well that certainly helps 🤣. I'll need to get my multimeter to test the CPU socket but the POST card is reading 0A08. Also I tried messing with the cache configuration to make sure it was correct and it no longer beeps, however I accidentally shorted some pins on the rear of the motherboard while trying to make sure the power connector was secure (bad idea to do that while it's on, I know) and for some reason it started beeping again like before. IDK if I really want to do that again with the POST card 🤣. I ordered some 30-pin memory sticks as well to see if those work better so I'll let you guys know how that goes on Monday.

If it stopped at 0A 08 it means last code it got was 0A, on Phoenix bios that should be "0A Initialize CPU register." so maybe that means that it's CPU problem after all?

That is if it still shows that after short 😬