Lenovo G31T-LM2 Not posting

[s_henya]

Hey,

i always wanted to get in deeper
about desktop boards repairs besides easy fixes as blown caps or FETs

i used to throw many 775 boards that refused to post.

So, this board was attempted to be fixed by a previous tech,

4 caps already has been replaced 470uf/16v

tested the board with good known cpu ram and psu.

the board powers up but no display on the onboard vga, or external pcie card.
i can hear a little attempt to beep but thats it, cpu fan working.

any ideas what else to test, or just give up on this one ( i have 3 more boards that wont post, and i really need a spare board, used my last one a month ago)

[momaka]

Re: Lenovo G31T-LM2 Not posting

The first thing I see wrong is bent pins on the yellow IDE connector on the board. I think two are touching - get those straightened out.

Next, check the CR2032 CMOS battery. Some motherboards will not boot if it's weak or dead. I just had this happen on an Intel motherboard like 3 days ago.

Use only one RAM stick, and preferably something old and highly compatible, such as 256 MB or 512 MB.

There seem to be some brown Chemicon caps on the motherboard. Not sure what series they are, but if KZG, then a good starting point would be to replace all KZG caps.

Finally, check the standard voltages on the motherboard with a multimeter:
CPU V_core (voltage depends on the CPU)
CPU Vtt (1.1-1.2V for LGA775, if I remember correctly)
RAM Vdd (1.8V)
RAM standby (1.2V, I think)
Northbridge Vcc (probably 1.5V to 1.6V)
Southbridge Vcc (always on, usually 3.3V)

Using this picture as a referene:
https://www.badcaps.net/forum/attach...6&d=1408540657
...
CPU V_core is located under the group of those small caps with red stripes around the CPU socket.
CPU Vtt is the Source pin of that lone MOSFET next to a lone brown (KZG?) cap, right by the CPU 4-pin 12V connector.
RAM Vdd is connected to the left side of the toroidal inductor, under the red IDE connector.
RAM standby should be connected to a bunch of small 4-way array SMD resistors between the RAM slots.
Northbridge Vcc is connected to the toroidal inductor under the PCI-E slot.
Southbridge Vcc is likely connected to that single cap between the Southbridge and RAM slots.

[s_henya]

Re: Lenovo G31T-LM2 Not posting

I am sorry but i could not finish the tests and update.
My client decided not to fix it.

i had to return it back.

Sorry...

[kalimuthu]

Re: Lenovo G31T-LM2 Not posting

Try to update bios