Which components on hp nc6400 motherboard can cause input power failure

Used motherboard, Nick?

http://www.ebay.com/sch/i.html?_nkw=nc6400+motherboard

Also wear an ESD wrist strap, and have it's alligator clip attached to a good ground source.
Average cost is $3 to $6.

Support homepage,

http://h20000.www2.hp.com/bizsupport/TechSupport/Home.jsp?lang=en&cc=ca&prodTypeId=321957&prodSeriesId=1847703&lang=en&cc=ca

Service Manual,

http://h20000.www2.hp.com/bizsupport/TechSupport/DocumentIndex.jsp?contentType=SupportManual&lang=en&cc=ca&docIndexId=64179&taskId=101&prodTypeId=321957&prodSeriesId=1847703#3

HP Compaq nc6400 Notebook PC Maintenance and Service Guide

24 Apr 2007 / 4.61MB

Regards,
joecoolvette

Does it start up at all ? Will it start up in Safe mode ?

Heat will cause computer components to expand sometimes not being able to make connecting to the hard drive. Could be a problem with the Hard Drive or the Hard drives PCB http://www.onepcbsolution.com/ Motherboards can go bad for many reasons, although there are a few common culprits. Among the most common causes of motherboard failure are excess electrical shocks, physical damage, or excess heat. Some of these dangers are inescapable, and may vary in likelihood depending on your computer model. Fortunately, there are some simple steps to protecting the computer's motherboard, or mainboard, as it might also be called.

Signs of a Failing Motherboard Detecting the difference between a failing or failed motherboard and other failing components can be difficult. This difficulty arises because all the components of a computer are plugged into the motherboard. Thus, if you are having trouble seeing the screen, it could be that the motherboard is failing or that the video card is failing. For this reason, any part of the computer failing can be a sign of a motherboard failure. However, there are some more specific indications that the failure is the motherboard. These include the system randomly powering down, all the components of the computer powering up without a live image appearing on the screen and only certain components of the motherboard working. b> Causes of a Failing Motherboard b> As with most computer components, the most common culprit when a motherboard fails is heat. All computer components are particularly sensitive to heat, and the inside of computer can become quite hot. Over time, this wears out the motherboard and can lead to its failure. A second common cause of motherboard failure is electrical damage. Commonly this occurs during computer maintenance such as installation of new peripheral devices. During maintenance, if the technician has static electricity built up on his or her hands, it can discharge into the motherboard, leading to a failure. Electrical surges, such as those created by lightning striking a power line, can also lead to motherboard failure. This is most commonly prevented by using a surge protector, but some surges are powerful enough to overpower the surge protector and destroy the motherboard. The last common cause of motherboard failure is physical damage. This can be in the form of water damage or actual physical impact. Although the motherboard is typically well protected, a strong enough hit to the computer case or the introduction of water into the case can lead to motherboard failure. b> Diagnosing Motherboard Failure b> Determining that the motherboard is the cause of a particular symptom can be difficult. Although specialized tools exist to determine if a specific component has failed, the easiest method for determining which components are damaged is a simple bench test. This does, however, require having a second computer, or at least extra components. The method for this is to determine what possible causes could lead to the symptoms of motherboard failure. For example, if the system shuts down randomly, it could be the motherboard, the power supply unit, or connecting cables. In this case, you could plug the power supply unit into another system that is known to be working and if the problem persists on the other system, then the power supply unit is the likely cause of system instability. Similarly, if the computer powers up but fails to display an active screen, you can move the video card into a second, working computer and determine if the video card is bad. Then try using the good video card from the second computer in the damaged computer to determine if it is only the video card or if it is also the motherboard. Although this method is not foolproof, it is effective. b> Preventing Motherboard Failure b> A few simple steps can be taken to ensure the motherboard does not fail. While a motherboard may fail anyway, simply due to age or unforeseen circumstances, it is less likely to fail if you take a few simple precautions. First, ensure the computer is in a stable location where it will not be knocked over and will not be likely to have liquid spilled on it. Second, if any maintenance is performed that will expose the motherboard, use an antistatic wrist strap or discharge any static electricity before working in the computer by touching a grounded metal object. Third, keeping the motherboard clean and free of dust can ensure that it continues working, although some computer manufacturers do not allow the users to open the case during the warranty period. Last, ensuring you use a quality surge protector can prevent the motherboard from being destroyed by power surges. b> Laptops Laptop motherboards are more exposed to damage than desktop motherboards. Although they tend to stay cleaner, they are more likely to be exposed to heat due to the small case. They are also more likely to be exposed to impact since the computer is being regularly moved. When transporting a laptop, it is crucial to use a case designed for laptops that will prevent blunt forces from hitting the laptop. Also, many laptops have vents on the back and the bottom. As cooling the inside of a laptop is much more difficult given the confined space, ensuring that these remain unblocked while working on the laptop is critical. Learn where they are on your laptop and ensure you leave them unblocked while working and the laptop's motherboard should be effectively cooled. Hope this helps.

b>

Since you already tried another power cord (assuming that it was a working cord and for the exact same model). Then I would say your motherboard is dead.

test all power and data leads that attach to your hard drive SATA

the leads from your (motherboard to your hard drive) make sure they have a secure dust free connections and are not faulty

make sure all leads that are attached to your drives dvd\cd have secure connections and are not faulty

even something as small as faulty fan lead can cause you problems

computers need all of the data and power to travel through every working device and to have an end for a computer to be able work properly

a motherboard and a hard drive any leads between them will fail before your motherboard or your hard drive check all power and data leads make sure they are securely seated even the cd/dvd drives need to have current go through make sure these devices are working

check the CPU central processing unit make sure it has thermal paste and dust free secure seating

also check your computer ram modules and cmos battery make sure it has charge and they are dust free and securely seated some motherboards cmos batteries are soldered in

hope it helps

One bad lead or faulty connection point can cause a computer to shutdown continue restarting on a cycle or fail to detect your hard drive boot up

test all power and data leads that attach to your hard drive SATA

the leads from your (motherboard to your hard drive) make sure they have a secure dust free connections and are not faulty

make sure all leads that are attached to your drives dvd\cd have secure connections and are not faulty

even something as small as faulty fan lead can cause you problems

computers need all of the data and power to travel through every working device and to have an end for a computer to be able work properly

a motherboard and a hard drive any leads between them will fail before your motherboard or your hard drive check all power and data leads make sure they are securely seated even the cd/dvd drives need to have current go through make sure these devices are working

check the CPU central processing unit make sure it has thermal paste and dust free secure seating

also check your computer ram modules and cmos battery make sure it has charge and they are dust free and securely seated some motherboards cmos batteries are soldered in

hope it helps

What does the AC do? (Alternating Current)

Apparently not get rectified into DC electricity by the AC adapter, (Charger), or the rectified AC (Which is now DC), is not getting to the laptop.

Be sure the Battery is still good. They have a lifespan, and only last so long.

Verify, by performing a DC Voltage test with a multimeter, if the AC adapter is putting out the correct Voltage.

If it is an AC adapter for an HP Compaq NC6400 Notebook PC, the DC Voltage coming out of the AC adapter is supposed to be
18.5 Volts. (DC),

http://www.amazon.com/Notebook-Adapter-Presario-cq50-142us-cq50-110/dp/B001MQ4MNW

On the AC adapter plug going to the laptop, the center pin is the Positive connection.
The outer cylindrical metal shell is the Negative connection.

AC adapter puts out 18.5 Volts?
Have an assistant;

1) Gently wiggle the power cord coming TO the AC adapter.

2) Gently wiggle the cable coming FROM the AC adapter TO the laptop.

See if you get an intermittent reading on the multimeter. Indicates a broken wire.

[ An economical, but fine for this test, multimeter, can be purchased for as little as $8 to $12, here in the US.
Analog or digital is fine.
Available in a multitude of stores. An auto parts store is but one example ]

AC adapter checks out it's on to the DC Power Jack.
This jack is the round port on the laptop, that the plug from the AC adapter plugs into.

Battery removed use a wooden small object, and gently see if you can move the center pin around, for the DC Power Jack.

See if the rest of the DC Power Jack will move around.
ANY perceptible movement means a problem with the DC Power Jack.

The DC Power Jack looks like this not mounted to the motherboard,

http://www.batterystyle.com/compaq-nc6400-jack-p-436629.html

Click on the two views shown of the DC Power Jack.
The view on the left shows the jack from the back.
The view on the right shows the jack from the front. The view you see now.

Note that in both views the jack is shown upside down, in relation to how it actually sits on the motherboard.

The view on the left, (Back view), shows Prongs coming from the jack, that go down through the motherboard, and are then soldered.

The gold colored prong is the Positive prong. It goes to the Center Pin of the jack.
All of the silvery colored Prongs are for Ground, or Negative.

Where the Prongs are soldered to the motherboard, are called solder joints. Each prong has a solder joint.

It may just be that one, or more solder joints are cracked.
This would require disassembling the laptop down to the bare motherboard in your hand, then re -soldering any cracked solder joints.

[ Be SURE to use an ESD wrist strap, and have it's alligator clip connected to a good ground source, BEFORE working inside a laptop ]

It may be however that the DC Power Jack is damaged, and replacement is necessary.

HP Support > HP Compaq NC6400 Notebook PC > Manuals page,

http://h20000.www2.hp.com/bizsupport/TechSupport/DocumentIndex.jsp?contentType=SupportManual&lang=en&cc=us&docIndexId=64179&taskId=101&prodTypeId=321957&prodSeriesId=1847703

On this page click on - Service and maintenance information

(Under the - Quick jump to manuals by category - heading)

Under the bold - Service and maintenance information - heading, click on -
HP Compaq NC6400 Notebook PC Maintenance and Service Guide
(24 Apr 2007 / 4.61MB )

[ This is a PDF file. The computer you are using now has Adobe Reader on it, which uses PDF files.

After you click on the above file name, it may take up to 30 seconds, before the first page comes up ]

Need guidance in de-soldering, and removing the old DC Power Jack, and soldering in a new one?
Post in a Comment.

If the DC Power Jack checks out, you have a bad power correcting chipset. This is a type of Power MOSFET.
Motherboard replacement is the solution.

Regards,
joecoolvette

More than likely the battery is defective, even with a charger it will not run if the battery is an open circuit due to failure.

Unlikely. They both would have to be running a motherboard that you can take off the cpu. And the cpu socket would have to be exactly the same on both motherboards.

I too had same problem and I guess you too have the same problem as mine. VGA adapter is not working anymore. Hardware failure. You may need to change the motherboard.

HP Compaq nc6400,,is the bios pin on correct jumpers?

https://support.hp.com/rs-en/document/c00363478