Pull everything but the processor. If it doesn't beep when you power the system up, the board may have other issues. Make sure the buzzer/beeper works, too, though.

Mister Xiado wrote:

Pull everything but the processor. If it doesn't beep when you power the system up, the board may have other issues. Make sure the buzzer/beeper works, too, though.

It beeped and after some tinkering i managed to get it to boot? It seems having my Cf-IDE adapter causes lots of strangeness. Swapped it out and now its fine?

Now my floppy drive seems to be messing up, worked a few times, then i decided to move it back to a diffrent machine to save some files on disk from the old HDD, and then re-installed it on the dos rig.

Reports FDD Controller Failure? Trying to read off the drive provides only clicking noises. A bit of fiddling with cables and it seems to be, atleast recognized again. Although now it fails to read my boot disk that worked previously
Not sure if the controller card died, or the drive got busted somehow (?) 😭

Yuuker wrote:

It beeped and after some tinkering i managed to get it to boot? It seems having my Cf-IDE adapter causes lots of strangeness. S […]
Show full quote

Mister Xiado wrote:

Pull everything but the processor. If it doesn't beep when you power the system up, the board may have other issues. Make sure the buzzer/beeper works, too, though.

It beeped and after some tinkering i managed to get it to boot? It seems having my Cf-IDE adapter causes lots of strangeness. Swapped it out and now its fine?

Now my floppy drive seems to be messing up, worked a few times, then i decided to move it back to a diffrent machine to save some files on disk from the old HDD, and then re-installed it on the dos rig.

Reports FDD Controller Failure? Trying to read off the drive provides only clicking noises. A bit of fiddling with cables and it seems to be, atleast recognized again. Although now it fails to read my boot disk that worked previously
Not sure if the controller card died, or the drive got busted somehow (?) 😭

Maybe also have a look at your Power Supply

jesolo wrote:

Maybe also have a look at your Power Supply

Quiet possibly, it seems the old AT PSU is having issues turning on, and now even when plugged in, it just makes a buzzing noise and no fan spin. I'm guessing it might have taken the FD-drive with it.

Tried using a spair evga 500w atx psu with an atx-to-at conver (the one with the button). Caused nothing but a brief spark and the smell of light smoke near the mobos power connector (thankfully no fire).

Looks like a capaciter blew near the connector, im assuming that was a fail-safe to protect the other expansion cards?

Not particularly too sure where to go now 😒. Don't know if the board and its parts where just on the way out, or the EVGA adapted psu was too much.
Maybe my board was fualty with its power delivery? The adapter and the EVGA Psu seem to not do this on any other board i have.

(ah well, at least its an adventure, albeit a semi expensive one!)

Are you sure you plugged the AT power connectors correctly? i.e. such that the black wires go together in the middle. That is the #1 reason why there would be fireworks when turning on (assuming the EVGA PSU is outputting correct voltages).

Can you post a picture of the component that blew up? Are you sure it was a capacitor?

TheMobRules wrote:

Are you sure you plugged the AT power connectors correctly? i.e. such that the black wires go together in the middle. That is the #1 reason why there would be fireworks when turning on (assuming the EVGA PSU is outputting correct voltages).

Can you post a picture of the component that blew up? Are you sure it was a capacitor?

Iv attached a photo. Nothing else on the front or back of the motherboard looks burnt or damaged, same with the expansion cards.
i'm assuming the PSU is okay? I pulled it out of a working machine i disassembled a while ago, had no issues. Its this model here: https://www.evga.com/products/product.aspx?pn=100-W1-0500-KR
Black cables should have been matched.

Taking a shot and guessing this board is dead? (I have no soldering or repair skills towards motherboards)

Best case scenario, you just had a capacitor go bad.

However, sometimes it will be found that a particular AT supply, even when in new condition wouldn't fire up until it had a fairly decent load across it, sometimes just a board, CPU, RAM wasn't enough to get them going, needed a HDD plugged into power on it also. Hopefully by the time you've loaded a machine up with expansion cards it'll be enough load to take the platter drive off, but it makes things a PITA for testing sometimes. HDD works because motor is powered all the time.

BitWrangler wrote:

Best case scenario, you just had a capacitor go bad.

However, sometimes it will be found that a particular AT supply, even when in new condition wouldn't fire up until it had a fairly decent load across it, sometimes just a board, CPU, RAM wasn't enough to get them going, needed a HDD plugged into power on it also. Hopefully by the time you've loaded a machine up with expansion cards it'll be enough load to take the platter drive off, but it makes things a PITA for testing sometimes. HDD works because motor is powered all the time.

Ahh yes, thank you for the pointer! Can confirm my old AT-PSU is now working on my other test-bench with an hdd attached.

Video and sound card seem to be alive on the test-bench too, meaning they didn't go down with the 486 board. (Good, otherwise i would have been slightly peeved)

Assuming a cap went bad on the mobo, I don't know how to solder, guess I'm out of luck on this board?

I might be able to assist on that. Can you check to see what the rating of the tantrum (Tantalum) cap was that exploded like a light bulb? Also, where're you from? I have a desoldering iron (45W), no-clean flux, lead-free solder with rosin core, and a soldering iron (15W).

Just have to order a new cap and jumper wires (if necessary) to the correct traces provide if the traces are damaged.

bjwil1991 wrote:

I might be able to assist on that. Can you check to see what the rating of the tantrum (Tantalum) cap was that exploded like a light bulb? Also, where're you from? I have a desoldering iron (45W), no-clean flux, lead-free solder with rosin core, and a soldering iron (15W).

Just have to order a new cap and jumper wires (if necessary) to the correct traces provide if the traces are damaged.

I can't see any rating on it. The popped cap has no visible writing on it, the only thing i got is some writing above it on the motherboard that looks to say: C6+. Theirs a bunch of like-type numbers above the other caps
I'm In Canada.

Now regardless of me getting a new board (probably with more cache and extra ram, 4mb wasn't looking good, could just salvage the cpu) or getting it repaired, i'd personally like to save some money on *not* buying another Floppy Drive. Anyone know anything about installing dos on a CF card directly from a modern pc? Or is a drive absolutely the safest way to do it?

Yuuker wrote:

I can't see any rating on it. The popped cap has no visible writing on it, the only thing i got is some writing above it on the motherboard that looks to say: C6+. Theirs a bunch of like-type numbers above the other caps

Look at the other caps to see what they say.

bjwil1991 wrote:

Yuuker wrote:

I can't see any rating on it. The popped cap has no visible writing on it, the only thing i got is some writing above it on the motherboard that looks to say: C6+. Theirs a bunch of like-type numbers above the other caps

Look at the other caps to see what they say.

Based on the layout from the motherboard (where x is the blown cap)

10U[cap] [cap] [cap] [cap] [x] [cap] [cap] [cap]
C9 + C10 10U C8+ C710U C6 + C5 C12 10U+

There is text on the caps (hidden from view) that'll show the microfarad and voltage rating.

x µf and y V (x is µf and y is voltage)

µf=microfarad

bjwil1991 wrote:

There is text on the caps (hidden from view) that'll show the microfarad and voltage rating.

x µf and y V (x is µf and y is voltage)

µf=microfarad

Checking the nextdoor cap on the row, the only writing i can make out is on the back and reads 102z. Although some slightly different shaped caps (on the same row?) have different writing:

To the best of my eyesight, it appears to be like this
+A
| 10(maybe is says uf afterwords? Can't make it out)
|16

Can't see anything else, although my eyes could just be bad.

Wow. That was a solid-state capacitor and I've never seen one pop like that before. Usually it's the larger electrolytic caps that leak. Also, small orange disk caps like that aren't supposed to look like round light-bulbs. If it were ME, I'd get the ENTIRE MB re-capped by a professional. I got an Athlon XP MB recapped and it made a huge difference in RAM stability (it was throwing errors before) and HDD stability (hard drive disk access became more stable).

Tantalums can definitely go boom.

The 102 code means 10*10^2 pF, Z is a tolerance code meaning +80%/-20%.

FFXIhealer wrote:

Wow. That was a solid-state capacitor and I've never seen one pop like that before. Usually it's the larger electrolytic caps that leak. Also, small orange disk caps like that aren't supposed to look like round light-bulbs. If it were ME, I'd get the ENTIRE MB re-capped by a professional. I got an Athlon XP MB recapped and it made a huge difference in RAM stability (it was throwing errors before) and HDD stability (hard drive disk access became more stable).

Makes me wonder if the motherboard had issues in general. It did seem to act wonky during its brief period alive.
Curious as to weather this is covered under the 60-day warranty the ebay lister has although refund or eating-the-cost regardless, i feel i might-aswell just get a better board and some better extras at this point.
At least that's what i'm thinkin'

Currently considering either a QDI PX486P3 VER 1.0 mobo w\dx33, 256k cache and 8mb ram (and supposedly dx2 support although jumpers only seem to go up to 50mhz?) or a Biostar MB 1433/50 AEA-V Ver:1 \w dx2-66

Can't decide wich one.

Yuuker wrote:

Currently considering either a QDI PX486P3 VER 1.0 mobo w\dx33, 256k cache and 8mb ram (and supposedly dx2 support although jumpers only seem to go up to 50mhz?) or a Biostar MB 1433/50 AEA-V Ver:1 \w dx2-66

Can't decide wich one.

On a 486 you don't directly set the CPU speed, only the Bus speed, usually 25, 33, 40 and 50MHz. The multiplier is fixed in the various 486 cpus, 2x in Dx/2, 3x in DX/4.

Exploding is not an uncommon failure mode for aging tantalum capacitors. Wear on the dielectric is cumulative, and so after a time they can eventually explode without warning. It's likely just a decoupling cap and the board shouldn't be any worse for wear with just one missing.

Unfortunately, there also appears to be signs of damage from the original battery leaking. Even though it may not look terrible on the surface, the corrosion will slowly eat away at vias and internal traces. My guess is the exploding cap was a coincidence and the real cause of flakiness is probably due to corrosion damage.

If you want a trouble free 486, any board with soldered on NiCad/NiMh batteries should be considered suspect no matter how clean they look. Not the best news, but I'd suggest chalking this board up as a learning experience and looking for another motherboard that came with a coin cell from the factory.

EDIT: Regarding your other options, In my experience QDI generally made decent boards. I had several of their socket 7 boards I purchased new back in the day, they actually beat ABit to the jumperless craze but never got credit for it. There were several variations of the PX486P3, some with coin cells and some without. If the one you're interested in has a coin cell, it's probably a safe bet. Mine has no problem running up to a DX4-100, so I suspect you won't have any issues with CPU support.

On the other hand, Biostar's can be hit or miss. I've had decent luck with them too, but I shy away from the boards that have "Biotech" chipsets since those are just randomly re-branded chipsets from other makers. If you can find one with a reputable chipset like UMC or OPTi that also uses a coin cell, and not soldered on L2 cache, you should be OK too. Personally, I'd shoot for the QDI--again assuming it has a coin cell.

Good luck!