Desktop Motherboard Repairing

[Satyajit Dhar]

I have a defective destop motherboard ( Asus P5GD2-TVM/S ). It has a power problem. When i connect the motherboard with SMPS 24 ATX PIN and 12 v ATX PIN. The motherboard gets shut down. But when i connect the motherboard with 24 ATX PIN only and disconnecting the 12 v ATX PIN the motherboard runs.

The next step i do is i removed the P4 processor from LG775 socket and connected both the 24 PIN ATX Connector and 12 V ATX connector. The motherboard started running and after few seconds all the six electrolytic capacitors ( 4 Volt-680 micro farad) started to explode one by one. I am now confused where the actual problem may lie.

Is there anybody could help me regarding this matter?

 

[FvM]

Apparently a defective core voltage regulator. Probably total loss. The CPU chip may be damaged too.

 

[Satyajit Dhar]

" But as per your saying if the voltage regulator ic is damaged then it should be hot, but there is nothing such like anything."

 

[FvM]

I suppose, the core voltage regulator has simply a short between 12V and output.

 

[Satyajit Dhar]

Another motherboard of same model does have a VGA problem. The motherboard is working fine but does not give any display. I think the problem lies in VGA section. Which spare parts i should check...any idea?

 

[peter_england]

do you have pci debug card for test ?? if you have one then check reset, clock signal for normal on it then check for normal heating of processor chip then check core voltage is good , then check for power good signal route from vrm chip also check if some code is generated on pci debug card (code only getting generated if above all things are fine), also check ps/2 keyboard num-lock state for toggle on-off led if debug card shows proper post sequencing then you have only vga signal problem try to remove small transistors near vga connector one by one. good luck.

- - - Updated - - -

by the way do you have any motherboard circuit diagram having Intel h61 chip-set ??