ECS RX780M-A no POST

[Joe Black]

Doesn't POST, spins fans normally. No image or beeps whatsoever. I tried to check some voltages and Vcore appears OK at 1.2V (measured at caps just left of the CPU) and Vram is as on the pic attached.

Would be great if I could repair it, though it hasn't some value, mostly as a learning experience. I have a similar MSI (low Vcore, will make thread on it), and I should get a nice i7 combo which I can keep if repairable

[BleedCap]

Re: ECS RX780M-A no POST

That 16v polymer caps is Lelon.

[Joe Black]

Re: ECS RX780M-A no POST

OK, meanwhile I got brand new PSU for testing, checked CPU socket pins (all nice and neat), and removed those 5 LF series next to CPU because I got strange readings with ESR meter (in-circuit though, but only 27pF!?).

So I wanted to check them out, but have managed only to pull out negative lead out of PCB, and positive lead out of every cap an destroy them. no matter how much I heat them, I can't remove positive pins from board. Any tips on that? I got Weller soldering iron, adjustable to 450 degrees C, and mechanical solder pump.

When pulled those out, I measured only 5 Ohms on their connections, so 5 Ohms between + and GND of all 8 output caps next to CPU. From what I understood, that's OK for lower MOSFETs, but I cant figure out is it OK for output caps to have so low resistance to ground.
I checked another MBs, and got 100kOhms+ everywhere.

Note: Just later on I discovered another cap on MB that reads about 26pF with ESR in circuit. Grabbed my DMM with capacitance function, measured same cap in circuit and got 836 uF... So it had something to do with el-cheapo ESR in the first place, and i destroyed fine japs... Don't know why would ESR measure that bad, on other caps tested it does an OK job, just slightly higher readings.

[Pentium4]

Re: ECS RX780M-A no POST

Have you tried resetting the BIOS?

I have seen those OST by the 24 pin ATX connector fail before, without bulging. On the caps that you were having trouble removing, did you apply fresh solder to the positive joints, and while heating them, try wiggling them out? I have also noticed that VRM caps are more stubborn at coming out. However, even being Lelon polymers, I doubt there is anything wrong with them.

[Joe Black]

Re: ECS RX780M-A no POST

Have you tried resetting the BIOS?

Of course, multiple times. And battery checks out on 3.01V.

I have seen those OST by the 24 pin ATX connector fail before, without bulging.

They measure just fine in-circuit (sum of their capacities and low ESR), so I assumed they're OK.

On the caps that you were having trouble removing, did you apply fresh solder to the positive joints, and while heating them, try wiggling them out?

Sure thing, if I didn't apply a LOT of fresh solder I wouldn't be able to pull negative legs out also, and nothing else from the MBs I believe. Really tough stuff (this solder) which can suck massive amount of heat somewhere

However, many thanks, P4. The more I read, the more confused I get
One thing I didn't check is Vs for SB and NB, so if someone could point the right spots that'd be great.
I believe one is that MOSFET and cap just left of the huge heatsink, but not sure about another.