I have a emachines T6420 and i plug out the power led hdd plug

the cable connectors are the same color as the pins were they go.

LED lights are on? Fans spin? I suggest you have a bad Power Supply.

1) eMachines are noted to have low quality Power Supply's.
Saves eMachines money so they can sell budget computers.

2) A bad Power Supply is one of the leading causes of computer failure. I have, (Had actually), a shop half full of computers with this 'ailment'.

Some caused by the owners never cleaned out the inside of their computer, nor the inside of the Power Supply, with a can of compressed air for computers on a regular basis as needed.

3 to 5 years without cleaning the inside of their computer.
Mice could have made nests inside easily, with the 'Gunk' that was there. A bald eagle could have too. Rant off.

Others, caused by the computer manufacturer used a low quality Power Supply.
Low quality components used inside.
One of the major components that fails, is caused by a particular Electrolytic Capacitor that is used.

http://en.wikipedia.org/wiki/Capacitor_plague

3) Power Supply's used in PC's are a type of SMPS.
(Personal Computer. Statement holds true no matter what type of personal computer it is)

[ SMPS = Switched-Mode Power Supply
PSU = Power Supply Unit
All terms relate to a Power Supply used in a PC ]

A bad Power Supply will have a weak voltage power rail.
There are three major power rails used in the ATX form factor Power Supply, for an eMachines T6420 desktop computer.

A) The 3.3 Volt power rail (DC)
B) The 5 Volt power rail (DC)
C) The 12 Volt power rail (DC)

(Two D cell flashlight batteries produce 3 Volts DC)

A Power Supply with a weak voltage power rail, may have enough power to light LED lights, and spin fans, (or spin a few times, ans stop), but won't have enough power to turn the Processor on.

1) ALL the LED lights combined use less than 1 Watt of power

2) EACH fan uses 2 to 3 Watts

3) A typical Processor can use 51 to 125 Watts.
Depends on what Processor it is.

eMachines T6420?
Uses an AMD Athlon 64 3400+, processor.
(Socket 939)

[The motherboard used is an MSI ms-7207
Also known as K8NGM2-L ]

http://www.emachines.com/support/product_support.html?cat=Desktops&subcat=T%20Series&model=T6420

This Processor can use Up To 89 Watts.

http://en.wikipedia.org/wiki/List_of_amd_athlon_64_processors#.22Newcastle.22_.28CG.2C_130_nm.29

No Processor running, No computer.
No computer = No Video Signal

Suggest using a KNOWN to be Good, Compatible power supply, for a test unit, if available.

Should be the ATX form factor.

Approximately 6 inches Long, (15.24cm), 6 inches Wide, (15.24cm), and 3-1/2 inches Tall. (8.89cm)

250 Watts.
Correct amount of power cables, and the correct type.

it will be next to ur power led or u will find hdd led wrritten on the motherboard

look for mother board morking,look for the pin that indecates (PS) is for the power switch (PL) power lead,(PR)(P res).and HD led

Check on the processor installed inside the computer's motherboard, it might be loosen and make sure it is properly locked. Also check for the fan. Make sure the cpu is properly ventilated to avoid overheating that might cause the shutdown.

I found this right on this website, hope it works!
As for the fans, make sure your connections are tight and in the proper sockets.

Hi there
The front panel connectors are mainly,

• harddisk activity connector
• power switch connector
• reset switch connector
• power LED connector
• speakers connector
• USB connector

Harddisk activity connector
This normally comes red in colour and is labeled as HDD-LED
Power switch connector
This comes green in colour and is labeled as POWER-SW
Reset switch connector
This usually comes grey in colour and is labeled as RST-SW
Power LED connector
This is usually green in colour and is labled as PWR-LED
Speakers connector
This speaker will give different beep sounds during boot to tell the user if there is any errors. It occupies 4 pins, however only 2 is important for the function. Be sure to connect the red coloured cable to the positive polarity and the black to the negative.
Front panel connectors pins on the motherboard
Front panel connectors from the casing

Good luck and thanks for using FixYa!!

Try this link to Emachines page. After you put in the make and model and stuff you should be able to view the user manual for your machine. If this isn't what you need you are able to contact support from this page and maybe they can direct you to a more detailed explanation that may help more.
eMachines use specially-made boards for them so there is no manual as such as the boards aren't made to be distributed. Basically they would all use the same sort of connectors and blocks (and cases) to an extent that anybody can plug a connector into the right place and it will work.

The easy way to get round this is to find the power button first - try each two pin connector first, press the button and see if it comes on. If not, move along on the block until you find the right one. Then it's just a case of trial-and-error on the other ones to find reset, power LED and HDD led.


http://www.emachines.com/support/product_support.html?cat=Desktops&subcat=W%20Series&model=W4065

Lets start with the basics. Does the monitor have power, do you get a light on the monitor when you try to turn it on? If you do then do you get any lights on the computer when you try to turn it on? If the monitor has no lights on it check the power connections and if still no lights then try plugging it into a different outlet preferably directly into the wall. If still nothing then the monitor is bad. If the computer has no lights but the monitor does once again try plugging it in to a different outlet and if that does not work there is a problem with the computer most likely the power supply, CPU, or motherboard. If both have lights but you get no display on the monitor then check the connection between the monitor and the computer. if the connection is good (I would ***** in the screws on the sides of the connectors just to make sure there is a good connection) then there could be a problem with your video card.

MODEL NO.--INTEL 845 GVRS. problem is --- power led is on but no display and no beep sound. SMBS, RAM ,, PROCESSER, & HD Are all ok. Pls. tell me how can i slove my problem?