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need few ideas about waking up a motherboard

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First post, by pshipkov

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I have this ASUS 386 motherboard that is like completely squeaky new. Does not even have dust on it.
But the donkey refuses to light-up.

Triple checked all jumpers. Tried different types and amount of SRAM and RAM.
Verified bunch of lines around the battery area - all checked-out.
Recapped it. Turned out all original caps were just fine.
Picture below is with some of the caps removed - WIP condition atm.

So before i inflict more damage, i wanted to check with others what a good next step should be.
Keep replacing elements ?
There is a chance some of the ICs gave up ...
What do you think ?

retro bits and bytes

Reply 1 of 12, by H3nrik V!

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I have seen boards, way newer, though, which refused to boot if no CMOS battery was present. Might be worth a shot?

Please use the "quote" option if asking questions to what I write - it will really up the chances of me noticing 😀

Reply 2 of 12, by Predator99

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What is the Display on the Post-card?

Reply 4 of 12, by pshipkov

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I should clarify:
There is always a battery when testing.
The picture above shows the board in a WIP condition.

I tried PostCard, but cannot remember what it shown back then. Probably nothing definitive, if i don't remember it. But will try again soon. Good point.

retro bits and bytes

Reply 5 of 12, by keropi

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have you tried another keyboard controller ic?
have you checked the bios eprom (or tried a new one?) , if it's dead it could mean someone in the past connected the psu the wrong way
one other thing is to check for trace damage, even a small one could make a board not work (but I have the feeling it's the first thing you checked...)

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Reply 6 of 12, by derSammler

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Remove *everything* but the CPU and connect a speaker. Does it beep because of no RAM? If not, try a second CPU. Still nothing -> check voltages on all chips.

Reply 7 of 12, by pshipkov

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Ah, two really good ideas.
- i don't think i checked different BIOS(es).
- i actually don't have a PC speaker (i think). But time to find one.

@keropi - checked bunch of lines - all was good.

Forgot to mention - all components (cpu, ram, sram, chipset, etc) get warm over time - so there is current going through them for sure.

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Reply 8 of 12, by derSammler

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pshipkov wrote on 2020-03-16, 08:16:

Forgot to mention - all components (cpu, ram, sram, chipset, etc) get warm over time - so there is current going through them for sure.

That's no indication for correct voltage, though.

Reply 10 of 12, by verysaving

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OSC2 socket is unpopulated?

Reply 11 of 12, by pshipkov

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Mobo is "naked" on this photo. Otherwise there is oscillator there.

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Reply 12 of 12, by douglar

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You gotta have a pc speaker when the board won’t boot to get the boot codes.

If there are no beeps, is the ide plugged in backwards? Is the powersupply set to the right voltage?

Try no video card, no ram, no keyboard. Try hitting the reset switch a couple times.

After that you might want to look into getting a diagnostic card.

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