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computer wont turn on..


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#1 vokab310

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Posted 28 April 2011 - 07:47 PM

ok im going to try and explain this as best as i can, i bought a computer from a guy a little while back,it's not a name brand computer i belive he built this computer. i brought it home and it would boot up,windows and everything just fine.then it would just shut off on me with no warning or anything, after about 10 minutes.Now it will turn on and i get nothing on the screen then shut right back off in about 5 to 10 seconds. im not that good with computers as in hardware and all. but i would like to get this comp up and running again.I tried a new power supply with the same specs as the one inside and it didnt fix it. so i put the old one back in and returned the new one. i checked all the connectors and everything and it's all seated just fine.The computer has windows vista on it.if whom ever can help me needs more info on it and can explain to me how to get this info for them i would greatly appreciate it.

P.S i hope i posted this in the correct section of the forums.


thanx again.

vokab

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#2 MrBruce1959

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Posted 28 April 2011 - 09:17 PM

Hello and welcome to Bleepingcomputer.

Yes you are in the correct forum for the problem you are experiencing.

Can you please post the make and model number of the motherboard? You will most likely see this printed on the main board roughly in the area of the RAM slots.

Next time you boot up the computer, try entering the BIOS setup utility and see if the system still shuts down while you are in this utility, you can get there by simply following the prompt displayed on the screen that mentions press the ( X ) key to enter setup. I used the letter X as a place holder, but the common keys to press to enter setup are F2 or DELETE.


If the computer shuts down while in this setup screen, then there is a problem with the motherboard.

Please post back the results.

Bruce.
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#3 Suicide King

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Posted 28 April 2011 - 11:33 PM

@Bruce: I assume you're suggesting the BIOS utility because you can enter it before the mobo makes use of the cards/drives attached to the computer? (And thus, since cards/drives aren't in use yet, they can be eliminated as problems?) What do you think about going one step further, and disconnecting everything from the mobo except for the RAM, CPU, and PSU?

#4 vokab310

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Posted 29 April 2011 - 11:17 AM

@bruce thank you for your reply, as for entering in bios i can't cause it dont stay on long enough its a (turn on shut right back off deal) lol. As for the motherboard i belive i have the right numbers for you. i hope this is right if not if u have any extra time on your hands and also have yahoo messanger i added my contact info to my profile feel free to add me to messanger. i am on it all the time. thank you for your help.ill be waiting for the next post.

motherboard winfast n15235.
video card ati radeon sapphire x1950 pro

Edited by vokab310, 29 April 2011 - 11:24 AM.


#5 dc3

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Posted 29 April 2011 - 11:29 AM

Bruce suggested the following...

If the computer shuts down while in this setup screen, then there is a problem with the motherboard.


Because of the way it progressed from staying on for about ten minutes to shutting down immediately there is a good chance that the problem isn't the motherboard. But you can use the method outlined below to see if it is the motherboard. I suspect that the computer will continue to shut down immediately. One of the possible causes of this could be overheating. This could be because the CPU is over heating due to a lack of air circulation through the heat sink due to accumulated dust, or a lack of thermal compound between the CPU and the heat sink. Is the heat sink free of dust?

Try the test below and let us know the results.

The purpose of this procedure is to bypass the motherboard to test the PSU.

When a computer begins the boot process the motherboard initiates the start up of the PSU. Because of this it is difficult to determine whether the problem is with the motherboard or the PSU when a computer shows no signs of starting up. The purpose of the procedure is to determine if the problem is with the motherboard or the PSU. For safety purposes please follow the instructions step by step.

This test is for ATX PSUs. Some manufacturers use non-ATX PSUs with 20/24 pin connectors that do not have the same pinout as a ATX PSU.

First, shutdown your computer. Then unplug the power cable going into your computer.

Once you have opened the case, touch the metal of the case to discharge any static electricity.

The connector of the PSU which connects to the motherboard is readily recognizable by the number of wires in the bundle. To disconnect it you will need to press on the plastic clip to disengage it and then pull the connector up and away from the motherboard. Please take notice of the location of the locking tab and the notch on the socket of the motherboard, this will only connect one way as it is keyed. This wire bundle will have a memory of the way it has been installed and will want to bend back that direction, you may have to play around with it to find a position that the connector will stay in the same position while you run the test.

Posted Image

From the top left to right the pins are 13-24, the bottom from left to right are 1-12.


Please notice that there are PSUs with 24 pin and 20 pin connectors, the location of the green wire in the 24 pin connector is #16, and the green wire in the 20 pin connector is #14. If you look at the connector with socket side facing you and the clip on the top the number one pin will be on the bottom left corner. This makes the pin out for the 24 pin connector from left to right 13-24 on top, and 1-12 on the bottom. The pin out for the 20 pin connector from left to right is 11-20 on top , and 1-10 on the bottom. If you look at the connectors you notice that these are sockets that fit over the pins on the motherboard where the PSU cable attaches, this is where you will place the jumper. For a jumper you will need a piece of solid wire about the size of a paper clip (20-22 awg), preferably a wire with insulation. It will need to be large enough to fit firmly into the socket so that it will not need to be held in place while testing. You are at risk of electrical shock if you are holding the jumper when you power up the PSU. Insert one end of the jumper into the socket of the Green wire, and insert the other end into the socket of any Black wire.

Once the jumper is in place plug the cord back in. If the PSU is working properly the case fans, optical drives, hdds, and LEDs should power up and remain on. I would suggest that you not leave this connected any longer than is necessary for safety purposes.

To reconnect the 20/4 pin connector unplug the power cord, remove the jumper, and reconnect the connector. Take a moment at this time to make sure that nothing has been dislodged inside the case.

Edited by dc3, 29 April 2011 - 11:30 AM.

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#6 MrBruce1959

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Posted 29 April 2011 - 01:28 PM

@ vokab310, I believe the suggestion made by dc3 in regards that the processor may be experiencing heat issues is a good probability, I would look into this first.

All the suggestions made above are good ones to follow.

@ suicide king, good suggestions, I was merely wanting to know if the system was capable of staying on for any length of time with just the BIOS screen loaded, this would then point to the processor as being the primary culprit/primary problem area.

The RAM is not used in the BIOS setup screen, the BIOS chip has its own memory, as for PSU, vokab310 stated he purchased a brand new PSU and tried it on this computer, with the same results, so I do not feel the PSU is the issue here.

Other hardware such as mouse, keyboard, drives, external devices would not cause a system to shut down several minutes later, they would cause issues as soon as the system is booted up.

Being that the system did or does run for some length of time and then shuts down, it sounds more like a CPU over heating issue than anything else.

Bruce.

Edited by MrBruce1959, 29 April 2011 - 01:36 PM.

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#7 MrBruce1959

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Posted 29 April 2011 - 02:21 PM

motherboard winfast n15235.

That number above is not exactly the model number of the motherboard.

I have done a web search on that number just out of curiosity to see what I came up with.

Besides using the BIOS string code as a reference, you may have to check the motherboard more closely for either a sticker or another set of numbers.

Foxconn may be the initial vendor of this motherboard. http://www.foxconnchannel.com/index.aspx

However I want to warn you that using winfast n15235 may not point you directly to your motherboard model on any web site.

The boards were made for various vendors under various model names for Acer, Packard Bell and a few other companies over the years.

Older motherboards usually display a BIOS string number at the bottom of the screen during the initial POST, pressing the PAUSE
button on the keyboard during this screen can cause the screen to sit at this stage long enough to get the entire BIOS string number, or enough time to take a photo of the screen with this string visible in the photo.

This string as I recall, can have as many as 24 characters in it, including numbers and letters, if you can get an image of this string up for us to see, there is a possibility the motherboard can be correctly identified.

I went through this same issue years ago with a PCCHIPS motherboard, I had to use the BIOS string to correctly identify the vendor and model number of the motherboard.

Bruce.
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#8 vokab310

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Posted 29 April 2011 - 04:54 PM

wheewww,,,, i found it lol it was on a white sticker right next to where i found the other numbers. sorry about that bruce for i am a n00b lol. this is the motherboard that is in this pc. i can also take pictures if need be and post them for you. here is the motherboard.

http://www.foxconnchannel.com/en-us/product/Motherboards/detail_overview.aspx?ID=en-gb0000202

#9 vokab310

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Posted 30 April 2011 - 06:28 PM

ok after following the steps from the above post,about the psu every thing starts up the fans and all, but im getting no initial beep like it would do normaly i have not tried running it like this hooked up to a monitor or keyboard...ect... so with this happening is it telling me that the psu is bad ? im going to hook it to a monitor and stuff and see what i come up with. i will post further..

once again i appreciate all the help i have got from this forum and will recomend this forum to anybody with computer issues.


vokab

ok i plugged everything in like normal with the pins still jumped. i still got no beep and nothing on the screen but the comp did stay on this time and to double check i took the jumper back out and tried to boot and it turned on and shut right back off back to the initial problem.

Edited by vokab310, 30 April 2011 - 06:37 PM.


#10 dc3

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Posted 01 May 2011 - 10:35 AM

The procedure you did by passed the motherboard entirely in order to see if the PSU will power up the peripheral devices, this is why there were no beeps from your motherboard. The fact that the PSU will turn on and stay on with the motherboard bypassed indicates that you have a problem with your motherboard.

At this point there are no other indications that there is a problem with the PSU, but if you want to test it, have access to a voltage meter with a DC scale and know how to use it, you can use the procedure below to test the PSU rail voltages.

Reading PSU Rail Voltages

Caution: Please read this before continuing.


∑ Since it will be necessary for your computer to be on during this procedure, you need to be aware that you will be working with live 12Volt DC potentials, which if handled improperly may lead to electrical shock.

∑ There are electronics inside the case that are very susceptible to electrostatic discharges. To protect your computer, touch the metal of the case to discharge yourself of any electrostatic charges before touching any of the components inside.

∑ If you are not comfortable doing this procedure, then I would suggest that you not use this tutorial. The risks involved are minimal, but are there nevertheless. Anyone who uses this tutorial will be doing so at their own risk.


There are two devices commonly used to read the rail voltages: a PSU tester, and a multimeter.

The PSU tester is the easiest to use since all that is necessary is to plug the different connectors into the tester and read the results on the LCD display. The problem with most of these is that they only perform a pass/fail test. They will not provide you with actual voltage readings.

There are a variety of multiple meters, but this tutorial will address Analog and Digital multimeters. The advantage of these meters is that you will be able to obtain accurate real time voltage readings.

For those of you who wish to know more about multimeters there is an excellent article in Wikipedia.


Analog Multimeter

Posted Image


An Analog multimeter is a little more complicated to use. Both Analog and Digital multimeters need to be set to the appropriate voltage, but with an Analog multimeter, you will need to choose the voltage range and must read the proper scale.

The Analog multimeter uses a needle display which moves from 0 across the scale until it reaches the voltage being tested. This multimeter has five major linear divisions with multiple scales to read a variety of ranges. An example would be three different ranges. The first is graduated in increments of 0 through 5, the second, 0 through 10, and the third, 0 through 25. Each of these ranges are subdivided into divisions that are graduated into tenths. In order to read 12 volts the 0 through 25 range would be the appropriate one.

Because DC voltage has positive and negative potentials this device is polar sensitive, this means that if you reverse the two probes when reading a positive DC voltage it will read as a negative voltage. This is actually necessary to read negative DC voltages. The two probes are differentiated by their color, Black (negative), and Red (positive). To read a positive DC voltage, the correct probes must be used with their corresponding potentials (positive to positive and negative to negative).

With the probes being used normally to read a negative DC voltage, the needle moves from the 0 to the left, "pegging" the needle. By reversing the probes you can properly read the negative voltages.

Digital Multimeter

Posted Image


The Digital multimeter (DMM) is much simpler to use. As was mentioned previously, you will need to set the appropriate voltage. One of the advantages is that the DMM has an LCD display with a numeric readout, so there are not any multiple scales to read. Another advantage is that most DMMs are autoranging when reading voltages, which means that you will not need to set the range with these DMMs. A DMM will read both positive and negative DC voltages and display them correctly. When reading a negative voltage, a minus sign will appear on the display before the numeric value. This still is a polar sensitive device, so you will still need to use the positive and negative probes with their corresponding potentials.

There are five different DC rail voltages which are color coded. The Black wires are always negative.

Yellow +12VDC

Blue -12VDC

Red +5VDC

White -5VDC

Orange +3.3VDC


There are only three voltages that can be measured easily without disconnecting the 20/24 pin connector from the motherboard: +12V, +5V, and +3.3V.

The +12V and +5V voltages can be read from a four pin Molex power connector.

Four pin Molex power connector

Posted Image


The same voltages can be taken from a four pin SATA power connector, but in order to read the +3.3V you will need to read this from a five pin SATA power connector as seen below.

Five pin SATA power connector.

Posted Image

To read these voltages you will need to insert the Black (-) probe into any of the black sockets, and insert the Red (+) probe in the different colored voltage sockets. To read the voltages from a SATA power connector it is easiest to insert the probes into the bac k of the connector where the wires enter. Unfortunately the sockets of the modular SATA power connectors are not accessible from the back, so the readings will need to be made from the socket side. Some probes are going to be too large to fit in these sockets, so you may need to insert a piece of wire into the socket of which you want to read the voltage of and place the probe on this for your reading. To reduce the potential of creating a short I would suggest taking the ground potential from another connector so that the two wires will remain physically separated.

Caution: It is very important to make sure that you don't allow the two probes to touch each other when taking the voltage readings. This will cause a short which could damage the PSU or other components.

To get accurate readings of the rail voltages it is important that there be a load on the PSU. In order to do this I would suggest downloading Prime95 for this purpose. This program was designed to be used by overclockers to put a full load on the RAM and CPU to determine the stability of their overclocking. Because of this it will put stress on the CPU and RAM which will create higher than normal temperatures. For this reason I would suggest not running this program any longer than is necessary. I would also suggest that an inspection be made of the interior of the case to make sure that there isnít an accumulation of dust which would impede adequate cooling. Pay special attention to the heat sink and fan assembly on the CPU. If there is a dedicated graphics card with a fan installed on it, look at this fan as well.


Readings should not have variances larger than +/- five percent.

Maximum.........Minimum
12.6V.................11.4V
5.25V.................4.75V
3.47V.................3.14V

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#11 vokab310

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Posted 01 May 2011 - 11:53 AM

yesi have meters and stuff to use . thank you for your post. im thinking should i just replace the mother board ? and if so do u guys have any other prefrence's on motherboards or should i get the same one. or is there any other steps i should take to narrow the problem down to any other hardware on the motherboard?


thanx vokab

#12 MrBruce1959

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Posted 01 May 2011 - 08:11 PM

I am going to offer some things you can try that won't cost you anything but a little bit of your time.

What I suggest you do is examine the processor heat sink closely for dust build up.

To assist you some what here, I am going to post a picture of what you should be looking for.

The image below is what a typical CPU heat sink and cooling fan look like.

Attached File  heat sink w fan2.jpg   5.6KB   0 downloads

In the image below, this is what dust can look like in a heat sink.

Attached File  dust.jpg   8.98KB   0 downloads

If your CPU heat sink looks anything like image number two above, your CPU will over heat and can cause the computer system to power off to avoid permanent damage to the processor.

You can remove this dust, in one of two ways.

Use a can of compressed air, you can purchase this in most computer related retail stores, or possibly a hardware store.

Just ask for a can of compressed air for the purpose of blowing out electronic components such as computer cases.

Point the nozzle into the heat sink and apply short but direct blasts of air into the heat sink.
This should start forcing the dust out of the fins, be advised, the container can become quite cold with continued usage, or the nozzle can become closed off by being frozen, just wait till things warm up and try again.

You can also accomplish this by using an old tooth brush or small paint brush used to paint portraits to remove the embedded dust.

There are methods of removing the heat sink from the CPU, cleaning off the old thermal grease and re-applying a bead of new thermal grease before re-installing the heat sink back over the CPU.

This procedure requires extreme caution and a clear understanding of what you are doing.

The number one major concern is guarding your system from potential damage caused by static electricity, this is something the human body carries and it can cause damage to sensitive electronic components.

To avoid this potential, make sure before you handle anything inside your computer case, you ground yourself first to the computer chassis by keeping one hand on the computer case. This safely equalizes the energy stored in your body with the energy that is stored on the motherboard.

Bruce.

Edited by MrBruce1959, 01 May 2011 - 08:39 PM.

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#13 vokab310

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Posted 02 May 2011 - 04:12 PM

thanx bruce,, i checked and there was no dust build up, but on the other hand the heat grease was hard so i cleaned it and added a drop more and reassembled and still have the same problem. any more suggestions would be greatly appreciated. thanx for the help. and your time.




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