Fired up a (Gigabyte GA7N400 Pro 2) motherboard that i had in storage, that was previously running OK
Board on bench with good ram and psu, with just the power and power LED connectors connected and a stick of ram.
Pushed power button fans started to spin then a couple of seconds later heard a crack sound (like the sound of a whip cracking) and then the smell of something that has burned, coming from the board.
After searching for a couple of hours, with a strong light and magnifying glass, i couldn't see any sign of burned components, bulged or leaking caps.
It wouldn't turn back on (even using a jumper across the 2 motherboard power-on pins), so i removed the connectors and 'paper-clipped' the earth and start terminals on the power connector, to get it going.
Noticed the RAM LED on the board lighting up and then another 'crack' sound, so immediately stopped the psu.
Since i couldn't find any noticeably burned-out components, i removed the CPU and the north-bridge, and didn't find any signs of damage there.
So checked voltage on the motherboard power pins - 4.1v
The south-bridge gets hot to touch - so power is getting to that
Removed the 6.3v caps - they look OK, and charge up/discharge similarly
What component, other than exploding caps, can make this crack sound, and burning smell with no visible signs?
What would be stopping a jumper across the motherboard power-on pins, from activating the psu?
TIA
Board on bench with good ram and psu, with just the power and power LED connectors connected and a stick of ram.
Pushed power button fans started to spin then a couple of seconds later heard a crack sound (like the sound of a whip cracking) and then the smell of something that has burned, coming from the board.
After searching for a couple of hours, with a strong light and magnifying glass, i couldn't see any sign of burned components, bulged or leaking caps.
It wouldn't turn back on (even using a jumper across the 2 motherboard power-on pins), so i removed the connectors and 'paper-clipped' the earth and start terminals on the power connector, to get it going.
Noticed the RAM LED on the board lighting up and then another 'crack' sound, so immediately stopped the psu.
Since i couldn't find any noticeably burned-out components, i removed the CPU and the north-bridge, and didn't find any signs of damage there.
So checked voltage on the motherboard power pins - 4.1v
The south-bridge gets hot to touch - so power is getting to that
Removed the 6.3v caps - they look OK, and charge up/discharge similarly
What component, other than exploding caps, can make this crack sound, and burning smell with no visible signs?
What would be stopping a jumper across the motherboard power-on pins, from activating the psu?
TIA
Comment