Step by step to repair mainboard:
Step 1: Power button:
If there is power step 2, otherwise check power supply circuit , including: stand by 3v3 , chip SiO, Southbridge.
Standby 3V3:
- 5v standby voltage from ATX will lower down to 3v3 for the southbridge, often using an ic 1117 or 1084, 1085, 1086 (pin 3; input ATX STB 5V, pin 2; output 3v3 STB. The main life bulbs are not used IC which uses a circuit with few or MOSFET transistor to stabilize pressure.).
- Check 3V3 at A14 pin PCI slot (see picture).
See PCI pinout in pinouts.ru
http://pinouts.ru/Slots/PCI_pinout.shtml
The cause of death 3v3 stand by this:
- Death ic 1117/1084/1085/1086
- Died LAN, Sound onboard
- Death southbridge
Chip SIO & Southbridge:
- 3v3 STB Otherwise, continue with chip SiO.
- Circuit power is booted, there are three following types (see picture):
Type 1: PWR button from the southbridge, ATX ps_on to MOSFET (polarity reversal) and the chip SiO.
Type 2: no MOSFET, ATX po_on go directly to SiO.
Type 3: PWR button on SiO.
PWR button (ps-on/pw on in F_Panel):
If the circuit well, southbridge activities, PWR button to have 2v5 ~ 5V. If lost, check SiO, Southbridge. If a volte PWR button, click the source is not, check Mosfet (polarity reversal), South Bridge chip, chip SiO.
Note: Quartz 32.768Khz southbridge bug will not work.
Step 1: Power button:
If there is power step 2, otherwise check power supply circuit , including: stand by 3v3 , chip SiO, Southbridge.
Standby 3V3:
- 5v standby voltage from ATX will lower down to 3v3 for the southbridge, often using an ic 1117 or 1084, 1085, 1086 (pin 3; input ATX STB 5V, pin 2; output 3v3 STB. The main life bulbs are not used IC which uses a circuit with few or MOSFET transistor to stabilize pressure.).
- Check 3V3 at A14 pin PCI slot (see picture).
See PCI pinout in pinouts.ru
http://pinouts.ru/Slots/PCI_pinout.shtml
The cause of death 3v3 stand by this:
- Death ic 1117/1084/1085/1086
- Died LAN, Sound onboard
- Death southbridge
Chip SIO & Southbridge:
- 3v3 STB Otherwise, continue with chip SiO.
- Circuit power is booted, there are three following types (see picture):
Type 1: PWR button from the southbridge, ATX ps_on to MOSFET (polarity reversal) and the chip SiO.
Type 2: no MOSFET, ATX po_on go directly to SiO.
Type 3: PWR button on SiO.
PWR button (ps-on/pw on in F_Panel):
If the circuit well, southbridge activities, PWR button to have 2v5 ~ 5V. If lost, check SiO, Southbridge. If a volte PWR button, click the source is not, check Mosfet (polarity reversal), South Bridge chip, chip SiO.
Note: Quartz 32.768Khz southbridge bug will not work.
