Emachines EL1352G runs without pressing power

[Herbssat]

Hello guys. I just got in an emachines that runs as soon as the power cord is inserted. It does have nvidia graphics but there is no video on the monitor. Only the cpu fan runs. Does anyone no where to start troubleshooting this problem and is it worth fixing?

[DJduck]

Re: Emachines EL1352G runs without pressing power

Is the PSU by any chance a bestec? If yes, then you have a dead PSU and a dead motherboard.

[DJduck]

Re: Emachines EL1352G runs without pressing power

Looking at the pictures from the internet, it seems to have a 80+ psu ???!!! Well, in that case it is probably not a bestec Are the caps ok? What brand are they? Also, is the video an onboard 6100 or 6150le? If so, then that may be the problem. Can you post a picture of the guts? The motherboard especially.

[Herbssat]

Re: Emachines EL1352G runs without pressing power

Thanks for the replies. I have torn the computer down to the motherboard but have not had a chance to look at the caps. It does have the nvidia onboard graphics as you suspected. I have changed out the power supply to no avail as the cpu fan still runs hard when the power cord is inserted. I have heard of the nvidia chip causing strange problems but never making the computer run without pressing the power button. The customer has already purchased another computer but I have taken this on as a personal challenge to fix as this seems to be commonplace with emachines systems.I will post a picture as soon as I can if it will help you to help me. Thanks.

[DJduck]

Re: Emachines EL1352G runs without pressing power

Ok. What was the psu brand? Might be that there is a short in the +5vsb on the board or the power switch. Try removing the power switch and shorting the power on pins with a screwdriver or any piece of metal to turn it on. If you have removed the switch and connected power and the machine doesn't turn on, then its a bad switch. Also, check all the caps. Do you have an ESR meter? Sometimes just a good full recap helps. Also, it might just be the chipset. Those things overheated in small and poorly ventilated cases and the little solder balls in the BGA (the solder balls that connect the chipset to the board) would loose conection. Those chips can get over 100 degrees celcius hot. Try heating the chip with an hot air gun or in the oven (reflow) at about 100-150c for 5-10 minutes and it might resolder itself. The hd 5450 card that is in my pc currently (my hd4850oc died) is fixed using the same method.

[Herbssat]

Re: Emachines EL1352G runs without pressing power

The power supply in this unit is a Liteon 80+. It has been confirmed good with my psu tester. There is nothing wrong with the switch. I have checked all caps with my esr meter and they check good also. There is one suspect transistor near the atx power connector that shows shorted in circuit between source and drain. The problem is that I do not have this TO-263 transistor and would entail me placing an order to digikey or mouser to replace it. It is probably a 2 fold problem with the transistor and nvidia chip. I wouldnt be surprised at all. Dont you just love the fresh smell of baked motherboard in the oven? Thanks for all your help.