Trying to verify bad motherboard

[T_C_]

Hi guys, been a long time since I've posted on here. I got a free eMachines t2560 2.5Ghz intel Celeron. I got it in a non-working condition, the power supply was flaky. I opened it up and it had several blown capacitors so I replaced that. I put in a new power supply (verified it was good with a tester) and it will not boot. It kind of does what it wants. I got it to go through the BIOS once, it displayed the boot splash, beeped, then went blank (not sure there is an OS on the hard drive I have in it anyways). Other than that one time, I have only gotten the PSU fan to go. Everything is disconnected from the motherboard, leaving RAM (256MB), CPU (socket 478 Celeron), and the Motherboard (stock eMachines). When I turn it on, there is no power going to the CPU fan nor any of the aux fans. The processor and heatsink are hot though, so I assume there is power going to the CPU? Nothing visibly bad on the motherboard.

That being said, what is the likelihood that the CPU is bad? I assume the RAM is ok since it will not even POST. I would have leaned toward the motherboard but it is an intermittent problem (well, bad except for the one time), and did not change after re-seating the CPU. Any help much appreciated!

 

[captaincranky]

That being said, what is the likelihood that the CPU is bad? I assume the RAM is ok since it will not even POST.

Is that actually what you meant to say? Because if the RAM >IS< bad, the computer will NOT POST

 

[T_C_]

Is that actually what you meant to say? Because if the RAM >IS< bad, the computer will NOT POST

I thought it would hit POST and spit out a beep code or hang up completely without showing anything on the screen. My CPU fan is not even spinning. Another thing I should mention - when the IDE is plugged into the HD, it will not spin, but unplug the IDE and the HD will power up fine so something is telling the HD not to turn on.

I'd imagine if the RAM is bad then power would still reach the CPU fan and other areas, right? It would turn ON but not really do anything else.

 

[captaincranky]

Well, sometimes, sometimes not, you will get a beep code. With your Intel chipset, it would be 3 short beeps for a memory issue.

An Emachine as old as the one we're talking about (socket 478) is likely to have a bad motherboard.

It' a somewhat contentious issue, whether the PSU fails and destroys the mobo, or vice versa. Usually there might be blown caps on the board, but I don't know if this is written in stone. The most common configuration is that they're both bad.

If your board was still good, and the CPU failed that would be the least common occurrence. Not to say, it couldn't be.

Could you jamb the HDD into another machine to verify whether there is an OS on the drive?

I'd imagine if the RAM is bad then power would still reach the CPU fan and other areas, right? It would turn ON but not really do anything else.

Not all voltages of a PSU necessarily fail at once. I had one that the CPU fan was the only thing that did work. That's anecdotal, I'm not saying that this is the case here.

 

[T_C_]

Thanks for the info!! I ended up just buying a new mobo and new RAM, gambling on the CPU. So now none of the computer is eMachines anymore except the case...and even that is broken :haha: (power switch, good thing I had an extra). For $80 total, not too bad.

 

[Kcircyrd]

Based upon the history of the T2560, your motherboard is a goner. Their eventual failure rate exceeds 67 percent. The system board apparently curls and stretches internally due to construction defects or shrinkage that appear as it ages. Nearly invisible cracks occur, breaking circuits, and ending the life of the computer.
The rest of your system, such as CPU, CPU fan, hard drive, memory, optical drives, and even the power supply will likely be ok. However, many power supplies are destroyed when the circuitry in the system board goes, probably from short circuits..

 

[T_C_]

Yup, piece of junk with the lifespan of an insect. But for less than a hundred bucks for 3/4 of the replacement parts, it should make a good light-use DVR/TV/living room PC for me and my roomates.

 

[captaincranky]

Glad to hear you're happy with the resolution to your predicament, enjoy.

 

[Tmagic650]

Thanks for the info!! I ended up just buying a new mobo and new RAM, gambling on the CPU. So now none of the computer is eMachines anymore except the case...and even that is broken :haha: (power switch, good thing I had an extra). For $80 total, not too bad.

That's exactly what I do when I run across a bad eMachines motherboard... Gut the machine and only use the case... Enjoy!