Dear members,
I have a nice looking Gigabyte FM3+ 990fx board here.
Symptoms: Plug the board in and no response from power switch.
Initial inspection: Everything seemed fine apart from
So anyways when turning on the power at the psu, i found that the 3.3v near the pch area was not present. measuring at the battery positive terminal there there was no voltage.
Checked around and burned my finger on the LDO voltage regulator which is part (L1117LG) 1A Fixed and Adjustable Low Dropout Linear Regulator (LDO). it powers the PCH hub (southbridge chip).
So I thought it was shorted so I removed the part. I checked the resistance of the output and it was reading less than 4 or 5 ohms. I powered up the output of the circuit with 1.2v through voltage injection and it seems to power up without a short drawing about 400 500 ma. nothing got hot apart from the chip. it also went to the battery circuit because the positive terminal of the battery also read 1.2v. I didnt think to increase the voltage because at the time i wasn't exactly sure which power rail it was.
I replaced the LDO reg with another one from an old motherboard i had and decided to fire it up. as soon as i flick the PSU switch the LDO began to heat up rapidly. Checked at the battery and it read 1.0-1.1 volts instead of the expected 3.3v also the Output of the LDO also read 1.1v. so I thought something must be shorting?
I iced up the entire area with some camping gas to see which component might be shorting and only 2 components heated up.
1. was the LDO reg, it heats up first
2. the crystal heats up second.
Theres a short video here https://photos.app.goo.gl/JxPx3moFDUv56YRZ7
Nothing else seemed to heat up to indicate any shorted capacitors?
So could it be a short inside the PCH chip? it sure gets hot right away only on stand by power, even before the main power is switched on.
If it was where would be the best place to find a replacement? is it even worth replacing?
I have a nice looking Gigabyte FM3+ 990fx board here.
Symptoms: Plug the board in and no response from power switch.
Initial inspection: Everything seemed fine apart from
- Low resistance at the memory 1.5v inductor coil (10 ohms)
- Low resistance at the PCH power supply near the bottom center of the board (less than 5 ohm)
So anyways when turning on the power at the psu, i found that the 3.3v near the pch area was not present. measuring at the battery positive terminal there there was no voltage.
Checked around and burned my finger on the LDO voltage regulator which is part (L1117LG) 1A Fixed and Adjustable Low Dropout Linear Regulator (LDO). it powers the PCH hub (southbridge chip).
So I thought it was shorted so I removed the part. I checked the resistance of the output and it was reading less than 4 or 5 ohms. I powered up the output of the circuit with 1.2v through voltage injection and it seems to power up without a short drawing about 400 500 ma. nothing got hot apart from the chip. it also went to the battery circuit because the positive terminal of the battery also read 1.2v. I didnt think to increase the voltage because at the time i wasn't exactly sure which power rail it was.
I replaced the LDO reg with another one from an old motherboard i had and decided to fire it up. as soon as i flick the PSU switch the LDO began to heat up rapidly. Checked at the battery and it read 1.0-1.1 volts instead of the expected 3.3v also the Output of the LDO also read 1.1v. so I thought something must be shorting?
I iced up the entire area with some camping gas to see which component might be shorting and only 2 components heated up.
1. was the LDO reg, it heats up first
2. the crystal heats up second.
Theres a short video here https://photos.app.goo.gl/JxPx3moFDUv56YRZ7
Nothing else seemed to heat up to indicate any shorted capacitors?
So could it be a short inside the PCH chip? it sure gets hot right away only on stand by power, even before the main power is switched on.
If it was where would be the best place to find a replacement? is it even worth replacing?
Comment