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Broken 486 MOBO?

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Reply 20 of 50, by keropi

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Pingaloka wrote:

[...]

Changed de 10v and 1000F to 10V and 1500F
and the 50v 10F to 63v and 10F

the soldering needs improvement but nothing that can't be fixed... what worries me is this:
"Changed de 10v and 1000F to 10V and 1500F "

you shouldn't have used a 1500uF capacitor in the place of a 1000 one

🎵 🎧 PCMIDI MPU , OrpheusII , Action Rewind , Megacard and 🎶GoldLib soundcard website

Reply 21 of 50, by Pingaloka

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NO? The guy at the store told me it was the same, actually better as it had a higher F value?!

Reply 22 of 50, by Qbix

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nope, you can change the V to a higher value, not the F.

Water flows down the stream
How to ask questions the smart way!

Reply 23 of 50, by Pingaloka

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So, could I try replacing them, or would the board be already broken?

Reply 25 of 50, by Pingaloka

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Ok, got the board booting again! I can't believe it! But, the original problem remains.....can it be a different capacitor?
I'm going to check all the capacitors ratings again....weird....

Reply 26 of 50, by jwt27

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If it's some PSU filtering cap, replacing it with a higher F value shouldn't make much of a difference.

But I see you scratched the PCB somewhat, especially on your last picture. In between the cap legs and to the right of that, one trace looks like it's going nowhere. I'd recommend to check continuity with a multimeter on "beep mode" and replace any faulty traces with wire.

Also, do you use a temperature controlled soldering iron? That is an absolute MUST HAVE when soldering electronics like this.

Reply 27 of 50, by Pingaloka

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jwt27 wrote:

If it's some PSU filtering cap, replacing it with a higher F value shouldn't make much of a difference.

But I see you scratched the PCB somewhat, especially on your last picture. In between the cap legs and to the right of that, one trace looks like it's going nowhere. I'd recommend to check continuity with a multimeter on "beep mode" and replace any faulty traces with wire.

Also, do you use a temperature controlled soldering iron? That is an absolute MUST HAVE when soldering electronics like this.

NO, it is the shittiest soldier you could find to be honest!
I'm going to check everything you said.
Thanx mate!

Reply 28 of 50, by Pingaloka

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Ok jw27, connected with a wire the trace you were talking about. Checked and bips.
Still, the MOBO hangs when HDD is found. Also keyboard freezes and you cannot enter BIOS if you wait too long.
If I have time this weekend I may try changing a couple more capacitors for the sake of it. Nevertheless I haven't been able to find anything wrong with them yet. So I wonder if the root of the problem are the capacitors.

Reply 29 of 50, by ratfink

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Can I just check... you have tried two motherboards and neither get past the POST to actually try to boot the operating system?

Are you using the same power supply and IDE cable?

Could be it's the PSU itself, the molex to the hard drive, or the IDE cable at fault.

Reply 30 of 50, by Pingaloka

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ratfink wrote:

Can I just check... you have tried two motherboards and neither get past the POST to actually try to boot the operating system?

Are you using the same power supply and IDE cable?

Could be it's the PSU itself, the molex to the hard drive, or the IDE cable at fault.

The other MOBO does boot and works perfectly fine. The problem was that I was using a 3Gb HDD that worked with the GA MOBO but not with the MSI one. I didn't noticed till I figured it out.
So I discard being the Power Supply or IDE cables.
Even if I don't put an HDD the MOBO acts the same. It feezes at boot, the keyboard hangs...

Reply 31 of 50, by Pingaloka

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Changed all capacitors guys!!!! Nothing......what can it be??? So many variables in the game.....Am I missing something.....mmmmm???
I've checked jumpers....they all seem to be in place....

Reply 32 of 50, by jwt27

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Have your tried stripping it down to the bare minimum? Install only one RAM stick, remove the HDD and boot from floppy, remove all expansion cards except video, etc.

If that doesn't help, maybe your BIOS chip got corrupted or something. If that is even possible.

Reply 33 of 50, by Pingaloka

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jwt27 wrote:

Have your tried stripping it down to the bare minimum? Install only one RAM stick, remove the HDD and boot from floppy, remove all expansion cards except video, etc.

If that doesn't help, maybe your BIOS chip got corrupted or something. If that is even possible.

Tried that jwt27, nothing! I'm also thinking the problem might be the BIOS itself.....I'm going to try booting from a Flash Card...

Reply 35 of 50, by Pingaloka

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It is for the Gigabyte one! I'm going to try this out. Thanx a lot jw27!
BTW how do I flash the bios if I can't access DOS?

Reply 36 of 50, by carlostex

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You can't unless the BIOS chip is an EEPROM.

Reply 37 of 50, by jwt27

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Pingaloka wrote:

It is for the Gigabyte one! I'm going to try this out. Thanx a lot jw27!
BTW how do I flash the bios if I can't access DOS?

Use a working system with the same BIOS chip, boot to DOS, insert the 486 BIOS chip, and flash it 😀

carlostex wrote:

You can't unless the BIOS chip is an EEPROM.

Are not all BIOS chip EEPROMs? I don't think I've ever seen an EPROM on a 486.
If it IS an EPROM, and the sticker has been damaged... "well there's your problem."

Reply 38 of 50, by carlostex

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jwt27 wrote:

Are not all BIOS chip EEPROMs?

No. Actually all 486 boards i own have EPROM. Except for my A-Trend ATC1425B, for which i got a replacement EEPROM that was pin by pin compatible with the original EPROM. Plus, even if some boards might have EEPROMS, does not mean you can program it on the board itself. You can't do that on some boards. In that case one needs to remove the chip and erase and program externally. In fact, provided you can find a suitable EEPROM to replace an older EPROM, makes your life easier as you'll never need to erase a chip with UV light.

Reply 39 of 50, by RacoonRider

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*idiotic post I wrote not knowing there were more pages has to be deleted*