Soyo SY-7VBA133 Won't react to power on. Could it be this capacitor?

[silencerar]

Hi! I have an old SY-7VBA133 that I can't manage to turn on. The power supply works and the processor does as well.

According to the manual it looks like it should have a 5v indicator led, which doesn't turn on (I really don't know where it's located either)

I've noticed that it has a capacitor next to the power supply connector that is slightly bulged. Before I try to replace it, do you think it could be the cause for this motherboard not turning on?

There are 3 capacitors, it's the one in the middle.

I've uploaded a picture of it here
Thank you so much!

[momaka]

Re: Soyo SY-7VBA133 Won't react to power on. Could it be this capacitor?

The bad capacitors *likely* shouldn't be the issue here as for why the motherboard is not turning on... but you should replace it anyways.

No power issue is usually related to Southbridge or superIO / LPC chip (on older boards like this, normally the latter.) First, make sure to read the manual and check that you're not missing any jumpers or jumpers in the wrong place (like CLR_CMOS and etc.) Also make sure you have a CR2032 battery in the board. This is usually not an issue on older boards to refuse to power without one, but just to be safe, have one in there. Also, when you say the board has "no power", do you mean to say the fans twitch and stop after pressing the power button, or does the board/fans not even do that? If it's the former, you may have a shorted MOSFET or regulator somewhere. If it's the latter, follow the 5VSB line and make sure the SuperIO / LPC IC is getting power (typically either 5V from the 5VSB rail or 3.3V standby generated from 5VSB.) If the board was lightning-struck, a dead LAN chip could be pulling down the 5VSB or 3.3V standby, so that can also make a board appear to be dead. Normally, though, you'd get a hot regulator or IC somewhere if that's the case. So look for hot spots too. Also look for any blown fuses. And lastly, if you're not the original owner of this board, inspect it carefully to make sure someone didn't drop something on the board or if the board itself was dropped, causing an SMD component to get knocked off somewhere (particularly around the Super IO and Southbridge area.)

Oh, and all of the caps should either be checked or replaced. With a board this old, a lot of the more obscure brands tend to go bad silently. While unlikely, that too can cause the board to appear dead.

In short, there are a lot of things to check. But try each suggestion above and report back what you find. Also, maybe post some good large pictures of your board, just to see if we can spot something that perhaps you might have missed.

[silencerar]

Re: Soyo SY-7VBA133 Won't react to power on. Could it be this capacitor?

Thank you such an in depth response! No, when I click the power button (the button works) nothing happens at all. No movement, nothing. I'll clean it a little and come back with a better picture! I'll also inspect it more closely. Thank you so much!

[Dan81]

Re: Soyo SY-7VBA133 Won't react to power on. Could it be this capacitor?

The bad capacitors *likely* shouldn't be the issue here as for why the motherboard is not turning on... but you should replace it anyways.

No power issue is usually related to Southbridge or superIO / LPC chip (on older boards like this, normally the latter.) First, make sure to read the manual and check that you're not missing any jumpers or jumpers in the wrong place (like CLR_CMOS and etc.) Also make sure you have a CR2032 battery in the board. This is usually not an issue on older boards to refuse to power without one, but just to be safe, have one in there. Also, when you say the board has "no power", do you mean to say the fans twitch and stop after pressing the power button, or does the board/fans not even do that? If it's the former, you may have a shorted MOSFET or regulator somewhere. If it's the latter, follow the 5VSB line and make sure the SuperIO / LPC IC is getting power (typically either 5V from the 5VSB rail or 3.3V standby generated from 5VSB.) If the board was lightning-struck, a dead LAN chip could be pulling down the 5VSB or 3.3V standby, so that can also make a board appear to be dead. Normally, though, you'd get a hot regulator or IC somewhere if that's the case. So look for hot spots too. Also look for any blown fuses. And lastly, if you're not the original owner of this board, inspect it carefully to make sure someone didn't drop something on the board or if the board itself was dropped, causing an SMD component to get knocked off somewhere (particularly around the Super IO and Southbridge area.)

Oh, and all of the caps should either be checked or replaced. With a board this old, a lot of the more obscure brands tend to go bad silently. While unlikely, that too can cause the board to appear dead.

In short, there are a lot of things to check. But try each suggestion above and report back what you find. Also, maybe post some good large pictures of your board, just to see if we can spot something that perhaps you might have missed.

Small issue - 7VBA133 uses VIA 686 southbridge, which seems to eliminate the need for a SIO chip. Only the ones equipped with 596B southbridge had SIO chips.

[silencerar]

Re: Soyo SY-7VBA133 Won't react to power on. Could it be this capacitor?

Small issue - 7VBA133 uses VIA 686 southbridge, which seems to eliminate the need for a SIO chip. Only the ones equipped with 596B southbridge had SIO chips.

You are right, it uses the VIA 686 southbridge. Some things I've checked/made sure of so far:

- Power +pin has 3.3v stable
- No component gets warm to the touch
- I've cleared the cmos using the jumpers
- New battery is in place

I still need to clean it and take a good picture.

[Dan81]

Re: Soyo SY-7VBA133 Won't react to power on. Could it be this capacitor?

I'd recap at least all caps that surround power components then try again. I'm thinking some of these could have gone short, hence why your board won't power up.

[silencerar]

Re: Soyo SY-7VBA133 Won't react to power on. Could it be this capacitor?

Should the bios chip https://www.alldatasheet.com/datashe...02NTPC-12.html be receiving 5v in the VCC pin while the motherboard is in stand by mode? it's not currently.