If you have a known good psu and replaced the old one and still no change, that suggests the mtrbd. is problematic. Maybe the start ckt. is done-in. Remove all devices making a mimium system, no drives periods of any kind. You need only the lowest amount of ram(1 stick?), video, kybd. and display, mouse. If you can boiot-up, then a device is holding you back. If you have other ram, try those or verify on another system they work. The cpu itself could be toast, but you can remove and simply power-ON and check results, it should beep away. Try all that and see what happens.
Here's a link for ya:
I've gone back to work on an E-Machines Model T-2824. The computer has an Intel D845GVSR motherboard and a Celeron D CPU. There is no Harddrive currently in the computer. I've obtained a connection diagram from Intel and verified that the power switch is connected properly and all other connectors are secure in their sockets. I have used a volt meter ,set on resistance to determine if there is continuity through the on/off switch; it checks out ok. Additionally, I have VISUALLY inspected all the capacitors for any obvious signs of defect, (bulging or burning). There is no smell of burnt components in the computer, nor any evidence of scortch marks.
When I plug the computer in and depress the on/off switch, the only thing that happens is a small green LED on the motherboard, immediately by the top right hand corner of the CPU illuminates. Nothing else happens. the fans do not spin , there are no "beeps" to be heard, and since there is no harddrive in the computer, there is no spin-up noise.
At this point I am leaning toward a faulty power supply as the cause of the problem. I have checked to make sure that the voltage switch is set to 115 volts, and that both the ATX connector is seated and latched in it's socket and the 20 pin main power connector is also seated.
The last thing I have done, is to use my volt meter, (Simpson 260), and insert the probes into the back side of the 20 pin main power connector to check for live voltage. I did this with the machine plugged in after depressing the on/off switch. With the ground probe touching the conductive surface of several different ground connections, (Pins 3,5,and 7) , I probed a number of different positive connections, specifically pins 1,2,4,6 and 11. On none of these pins did any voltage register on the meter.
At this point, would I be safe in assuming that my problem lies in the power source, or are there further diagnostics I can and should perform before replacing it?
As always, any input and assistance you can give me is very, VERY much appreciated. I am an amateur trying to learn something new.
PS: I have now replaced the power source,(PSU), and found no change