Question about Foxconn (945P7AA8EKRS2) Motherboard
What may be apparent in your mind, is not necessarily always conveyed in the typed 'prose'. Your single sentence usage to describe your problem, has left possible holes in the time/space continuum.
(Last half of last sentence, is obviously a bunch of prattle. Thought it sounded 'keen', since I am conversing with a retired electronics engineer, lol!]
Going with the premise;
Computer (A) will not work.
Installed identical mobo (MOtherBOard), from working computer (B), and now it will not switch on.
There are two possibilities why this is occurring, and a backup theory to support my claims...........
The first thing to check right off the bat, when diagnosing a desktop computer problem; is the Power Supply.
This, of course, also goes along with a cursory inspection; of the condition of the inside of the computer;
Plus, inclusively whether Electrolytic Capacitors, are bad on the motherboard.
(IF, Electrolytic 'caps' are being used, and not Solid Polymer Capacitors)
1) Dirty computer inside, and Power Supply failure, are the two leading causes of Desktop PC failure.
This statement is also supported on the internet.
[Yes, stating it is posted on the internet, by itself does not substantiate solid proof.... I could post that I'm president of the US, on the internet.........What DOES substantiate the statement's claim, is that it has been posted through the last 12 years at least, and by MANY people with first hand knowledge. Most posters fairly technical in background.
Plus I'm a computer repair tech, and can substantiate the claim with first hand knowledge, and years of background.
Therefore it has had numerous 'test experiments' performed, and the results always come to the same conclusion.
Kind of like Quantum Mechanics, the Theory of Relativity, and Mom's apple pie ]
You removed a working motherboard, and identical; from one computer, and installed it in a non-working computer.
Now the working motherboard, does Not work either.
The common 'culprit' it would seem to me, is the Power Supply.
Power Supply has a weak voltage power rail.
This is going with the premise that the Power Supply fan is spinning, LED's have lit up, and computer case fans may be spinning.
Not with the premise that you press the Power On button, and NADA!
However in the diagnostic flowchart to follow, the Power On switch, AND Power Supply; will be tested.
1) If ALL of the LED's were lit up at once, they would use less than 1 Watt of power.
2) EACH fan uses 2 to 3 Watts of power.
3) A typical Processor (CPU) can use 51 to 125 Watts of power.
Just depends on what Processor it is. (Intel Pentium 4 series, and comparable AMD's. Intel Pentium III's, and comparable AMD's, use less power)
This is why the simpy LED's may work, and case fans; but not the computer;
NOT enough power to turn the Processor on......
[ Desktop PC:
When the Power Supply is plugged into power, there is a constant 5 Volts present.......The 5 Volt Standby power.
You press the Power On button. This in turn presses against the Power On switch, and activates the Soft Power On circuit.
The Soft Power On circuit 'excites' the Power Supply, and turns it on. (Sounds like a 'seedy' novel)
The first I.C. to receive power is the BIOS chipset.
The Basic Input/Output System program is initialized.
BIOS looks to see what devices are connected, does a Ram Memory count, TURNS the Processor on; and hands the computer over to the Operating System.
(Windows is the O/S in this case) ]
Computer (Power Supply) not turning on when Power On button is pressed:
Suggest perform the simple test, to see whether the problem is the Power On switch; or Power Supply;
A paperclip is straightened out, and then bent into a U-shape.
Turn the U upside down. The top of the U-shape is wrapped a few times with black plastic electrical tape. (Or whatever color you prefer)
This taped area is for your fingers, and thumb to hold onto.
There are now two 'legs' sticking down.
24-pin ATX main power cable plugged into motherboard, Power Supply plugged into power.
Where the wires go into the main power cable's connector, is the BACK of the connector.
The U-shaped jumper wire is used on the Back of the 24-pin ATX main power cable's connector.
One 'leg' is inserted down into the socket hole, with the GREEN wire. The Green wire is the Soft Power On wire. (PS_ON)
Slides right down into the socket hole, RIGHT NEXT TO the green insulation of the wire, and touches a metal female terminal connector.
Every wire going into the main power cable's connector, ends in a female metal terminal connector. The U-shaped jumper wire MUST slide down into the socket hole far enough, that it touches that metal female terminal connector.
The other 'leg' of the U-shaped jumper wire, slides down into any socket hole; that has a Black wire in it.
The Soft Power On circuit uses that 5 Volt Standby power.
5 Volts DC.
However I am NOT stating that there may be a spark, as the U-shaped jumper wire is lowered in place. As you know, just the way electricity works.
Therefore you may wish to also wear a glove, on the 'jumper wire hand'.
IF, the Power Supply comes on, you have a bad Power On switch.
IF, the Power Supply does NOT come on, you have a bad Power Supply.
Power Supply fan spins; Power Supply is determined to be in the state of - ON:
Testing the voltage power rails:
The Power Supply in your desktop computer is an SMPS.
Switched-Mode Power Supply. Also known as the abbreviation - PSU. Power Supply Unit.
Converts the high AC voltage from your home, or business; into three LOW DC Voltages;
1) 3.3 Volts DC
2) 5 Volts DC
3) 12 Volts DC
In comparison two D cell flashlight batteries store 3 Volts DC.
Each one is a Voltage Power Rail.
They all end in a 'tap' for each voltage power rail, inside the Power Supply.
If the SMPS uses a transformer in it's design, then the three voltage power rails come from three 'taps' on the transformer.
If the SMPS does Not use a transformer in it's design, then the three voltage power rails come from individual circuitry within the SMPS's design.
Suggestion is to test the three main voltage power rails.
If the computer will not come on, when the Power Supply is determined to be in the state of ON, (Power Supply fan spins); then there is a weak voltage power rail.
Not enough power to turn the Processor (CPU) on........
A) Orange wires are 3.3 Volts
B) Red wires are 5 Volts
C) Yellow wires are 12 Volts
D) ALL Black wires are Ground wires. (Negative)
Test at the 24-pin ATX main power cable's connector,
Besides your multimeter, you're going to need a paperclip again. Two of them this time. (Unless you have a probe, that will take the place of a skinny paperclip)
These are straightened out, and now become jumper wires.
24-pin ATX main power cable plugged into motherboard.
Where the wires go into the main power cable's connector, is the Back of the connector.
One straightened out paperclip slides down into a socket hole, with an Orange wire. ALL Orange wires are 3.3 Volts.
Slides down into the socket hole, RIGHT NEXT TO the Orange insulation of the wire, and MUST go far enough down into the socket hole; to touch a female metal terminal connector.
(As previously described)
The other straightened out paperclip goes down into a socket hole, with ANY Black wire in it.
Power Supply plugged into power, Power Supply turned on; voltage is checked. Should = 3.3 Volts DC, or very close.
Now do the same for the 5 Volt voltage power rail. Choose any Red wire, and Black wire.
Again, the same for the 12 Volt voltage power rail. Choose any Yellow wire, and Black wire.
Low voltage power rail? Replace Power Supply.
No test equipment readily available?
(An economical multimeter, can be purchased for as little as $5 to $12. Auto parts stores are one place that carries them, albeit usually higher in price though.
I have seen them on checkout aisle racks, at major discount stores.
Economical in price, but quality is plenty good enough for the above test)
Then suggest use the Power Supply out of the working computer, for a test unit.
The problem is;
1) You didn't FOLLOW Anti-Static Procedures, and the delicate hardware components inside the computer; are now Static shocked.
Motherboard is a Frisbee, Processor (CPU) can have a hole drilled through it, and be worn for a neck charm.
2) Power Supply fan spins, computer does not come on; Remove ALL Ram Memory modules, ('Stick'), and reinstall.
They/it get bumped loose very easily.
PROPER procedure is to remove, and reinstall; so that you are ASSURED the Ram Memory module/s are seated tightly, and correctly.
Visual inspection ALONE will NOT do..........
3) You did not connect the main wires from the Front Panel, to the correct contact pins in the Front Panel header; on the motherboard.
(Power Supply does not come on)
4) The 4-pin ATX +12 Volt power cable, was not plugged into the motherboard. This is power for the Processor (CPU)
[Connects to 4-socket hole white, square connector on motherboard; to the Bottom/Left corner of Processor socket]
For further questions, or to have me clarify any statements I have made above; please post back in a Comment.
Posted on Apr 26, 2013
Testimonial: "It was bad capacitors on the motherboard and in the power supply. Two computers working now thanks."
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Posted on Jan 02, 2017
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