820-2530 | Green light, turns on | No display, no chime, no RAM beeps

[LucasVon]

Hello!

I have a 820-2530 that won't boot. It turns on, but the screen remains blank and there is no chime. No keyboard backlight also.
I removed the RAM and it won't beep.
When I turn it on after a while, it turns off by itself after a couple of seconds and then turns on again, then it stays on. The fan spins at 100% and doesn't slow down. CPU and GPU warm up.

Looked over the board and couldn't see any corrosion / water damage. In fact, it's surprisingly clean.

Any ideas where to start with this? Thanks!

 

[dukefawks]

CPU Vcore present on L7400, if not check R7420.

 

[LucasVon]

I'm getting 0.97V on pin 1 and 0.996V on pin 2

 

[dukefawks]

MCP_PS_PWRGD coming high? If yes try this ROM: https://drive.google.com/open?id=0ByfhQ_x0v-tZWm1HdWdSTDZkR00
That is about all you can do on this old board. If this does not help then it is probably a bad MCP or it was dropped. Also go over the board for possible knocked off components.
Is there any history on this board?

 

[LucasVon]

Just called the owner of the board. Turns out it was reflowed 2 years ago after it failed out of nowhere. This might explain it, in which case I don't think there's much I can do.
Will check MCP_PS_PWRGD tomorrow when I get back in though, thanks duke!

 

[LucasVon]

Getting 3.3V on MCP_PS_PWRGD

 

[dukefawks]

Probably a bad MCP then. Could still try the BIOS.

 

[stray77]

We're in a similar boat it seems, only no previous reflow here. https://www.rossmanngroup.com/board...413-820-2530-no-chime-no-display-but-turns-on

Would you mind measuring your R7780 and R7781 values just for me, mine both measure 193K but my schematics says they should be 255K and 806K respectively. I'm still confused by this.

 

[larossmann]

Resistors will always measure lower in circuit because there are multiple pathways inside the board for power to get from point A to point B. Resistors usually fail by going open circuit where the resistance is higher rather than lower so that is probably fine. To confirm you can remove the resistor from the board and measure it off the board but then it flies away into the fifth dimension to never be found so I usually don't advise this.