Your computer, Dell Dimension E521 Desktop PC, will not turn on, and someone told you the problem is the motherboard?
Unless you stated to this entity, that you spotted leaking Electrolytic Capacitors on the motherboard, how can they assume this?
I believe you should check whether the problem is the Power On switch, or the Power Supply.
1) The Power On switch is located inside the plastic Power On button. It is an ATX power on switch. (The Power On switch is a Momentary Contact Switch )
This is an example of an ATX power on switch, that I have found fits many desktop computers,
http://www.directron.com/atxswitch.htmlThe test to perform bypasses the Power On switch. It does NOT involve the Power On switch itself, however.
Bypassing the Power On switch turns the computer (Power Supply) on?
Problem is the Power On switch.
Bypassing the Power On switch does NOT turn the computer (Power Supply) on?
The problem is the Power Supply.
A) Computer on a table, computer unplugged from power, computer case open.
I would then lay the computer on it's side, on a towel, on the table, computer case opening UP.
Watch the cables attached to the computer.
This is so you can access the components inside of the computer more easily. This will become apparent in a moment.
Now follow Anti-Static Precautions.
Anti-Static Precautions:
Your body carries Static electricity. Static WILL fry out (Short Circuit) the delicate hardware components inside a computer.
Relieve your body of Static BEFORE reaching inside the computer.
(Have to restate) Computer on a table, computer unplugged from power, computer case open.
TOUCH an unpainted surface, of the metal frame of the open computer case.
This action will relieve your body of Static.
Should you leave your computer in the middle of working on it, (For ANY reason), be SURE to touch the metal frame again upon your return.
Now you are safe, and the computer is safe. Let's begin;
Inside your computer there is a power cable coming from the Power Supply, that plugs into the motherboard. This power cable I'm referring to is the 24-pin ATX main power cable.
This is an example of a 24-pin ATX main power cable, and it's respective connector on the motherboard,
http://www.playtool.com/pages/psuconnectors/connectors.html#atxmain24Female connector on motherboard shown in the Left photo.
Power cable connector shown in the middle photo.
The photo to the right shows the ATX main power cable plugged into the motherboard.
This is how it needs to be for the test. It also shows the color of the various wires going into it.
We only need to be concerned with Two wires.
The Green wire, and ANY Black wire.
The Green wire is the Soft Power On wire. It is also abbreviated as PS_ON.
ANY Black wire you see is a Ground wire.
A jumper wire is used to BRIEFLY connect the Green wire, to ANY Black wire.
(Again, the Power On switch is a Momentary Contact Switch)
The jumper wire preferred to use is a paper clip. The paper clip is straightened out, then bent into a U-shape.
Look at the U-shape upside down. The top/middle is wrapped a few times with black plastic electrical tape. This is for your fingers, and thumb to hold onto.
The 'legs' of the U-shape go down into the Back of the ATX main power cable's connector.
(I shortened 24-pin ATX main power cable to ATX main power cable)
Look at the photo to the right. See how the Green wire goes down into a squarish socket hole?
Look at the photo in the middle. See the metal tube shapes at the Front of the connector?
Brass looking, slightly square?
These are metal terminals. There is a metal terminal for every wire, going down into the ATX main power cable connector.
The 'leg' of the U-shape jumper wire goes down into the Back of the connector (ATX main power cable connector), RIGHT NEXT TO the existing wire that is in the socket hole.
It has to go down into the squarish socket hole far enough, to pass by the insulation of the wire, and Touch the metal terminal.
Example:
One leg of the U-shape goes down into the socket hole of the Green wire, right next to the Green wire, and touches the metal terminal.
The other leg of the U-shape goes down into a socket hole, with ANY Black wire, and touches the metal terminal pin.
The leg MUST touch the metal terminal pin.
The contact made is brief. No more than 2 seconds. (1001,..1002)
Shock warning. None.
The Soft Power On wire (Green wire) has 5 Volts DC going through it.
In comparison two D cell flashlight batteries produce 3 Volts DC.
HOWEVER, there may be a spark, as both legs of the U-shape jumper wire touch their respective metal terminals. Warning you in advance.
You are also holding onto the black plastic electrical tape. (One wrap of black plastic electrical tape will insulate you from 600 Volts DC)
IF, the jumper wire turns the computer on, (Power Supply actually), the problem is a bad Power On switch.
IF, the jumper wire does Not turn the computer on, the problem is a bad Power Supply.
The Power Supply used in a Dell Dimension E521 Desktop PC, is an ATX (Form Factor) power supply.
The form factor ATX for a Power Supply refers to the size, and shape of the Power Supply's case, and the power cables provided with the Power Supply.
The size, and shape of the ATX power supply case is approximately 6 inches Wide (Width), 5-1/2 inches Long (Length), and 3-1/2 inches Tall. (Height)
With the power cables offered with today's offering of ATX power supply's, there is no need to be concerned if the ATX power supply in question, has the needed power cables.
ATX power supply's sold now, have the correct power cables you'll need, and the correct amount of power cables.
This is just one example of an ATX power supply that will work,
http://www.tigerdirect.com/applications/SearchTools/item-details.asp?EdpNo=1389575&CatId=1078Scroll down to the bold heading - Detailed Features
Look at the chart under the subheading - Connectors
Note the first connector shown. This is a 20-pin plus a 4-pin main power cable.
Both power cables are used for your 24-pin ATX main power cable connector, on your motherboard.
This gives a little more information on a 20 + 4-pin ATX main power cable,
http://www.playtool.com/pages/psuconnectors/connectors.html#atxmain20plus4Note the photo to the right. This particular motherboard has a 20-pin ATX main power cable connector. It does not require the additional 4-pin power cable.
Yours does.
Do Not confuse the 4-pin ATX +12 Volt power cable, with the 4-pin power cable that comes with a 20 + 4-pin ATX main power cable.
The 4-pin power cable you need is in the harness of wires, for the 20 + 4-pin ATX main power cable.
There WILL be a 4-pin ATX +12 Volt power cable, however. This is an example of a 4-pin ATX +12 Volt power cable,
http://www.playtool.com/pages/psuconnectors/connectors.html#atx12v4(Color of the connectors for any power cable, does Not matter. They can be any color)
Dell Support > Dimension E521 Desktop PC > Service Manual,
http://support.dell.com/support/edocs/systems/dime521/en/SM_EN/index.htmIn the list click on - Technical Overview
Now click on - System Board Components
22 is where the 24-pin ATX main power cable plugs in.
(NOTE*
The 24-pin ATX main power cable connector, and the 4-pin ATX +12 Volt power cable connector, have a Lock on the side. The plastic rectangle on the side of the connector/s.
This Lock has a hook on the bottom end. The end that faces the motherboard.
The hook goes over a Tab on the female connector, on the motherboard.
The Lock acts like a see-saw on a playground. The top of the Lock is squeezed in. This action brings the hooked end away, from the Tab on the motherboard female connector.
Then the power cable CONNECTOR is wiggled, and removed from the female motherboard connector.
{ ONLY use the Connector when removing it. DO NOT pull on the wires)
2 points to where the 4-pin ATX +12 Volt power cable plugs in.
That's it for the Power Supply power cables.
1 points to where the Processor Fan plugs into.
5 and 6, point to where the Data cables from the SATA harddrive, and SATA optical drives, plug into.
(This is if the Dimension E521 has SATA optical drives, and not IDE { PATA} optical drives)
[ The SATA data cable connector has 7 contact pins in it. It is the shorter connector.
The SATA power cable has 15 pins in it. It is the longer connector.
IF, the SATA harddrive has a provision for using a SATA power cable, AND a 4-pin Peripheral power cable (Mislabeled as Molex), ONLY use just the SATA power cable. Otherwise the SATA harddrive will burn out. Sometimes not right away, but eventually it does ]
Going back to the main page for the Service Manual, click on -
Removing and Installing Parts.
Removing the Computer Cover is listed, as well as Power Supply.
For additional questions please post in a Comment.
Regards,
joecoolvette
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