Computer Won't Turn On

Discussion in 'hardware' started by Coolio10, Nov 7, 2010.

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  1. Coolio10

    Coolio10 Registered Member

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    I have a computer that will not even reach the boot screen (manufacturers logo). The orange HDD LED stays on constantly for a few seconds than turns off. The power supply seems to be working fine as the CD and DVD drives open fine, but the CPU fan does not start up. I think the motherboard might be failing. It was working fine until i starting moving through the BIOS settings, which during that it froze up and won't turn on. I removed the battery but still nothing. I left the battery out for an entire day and it booted up once, but once again froze when i moved through the BIOS settings. It hasn't turned on again since. The motherboard cannot be completely dead though as the signal to turn on obviously goes through the motherboard before it reaches the power supply.
     
  2. Searching_ _ _

    Searching_ _ _ Registered Member

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    Remove/unplug the hard drive and see if you can get to the boot screen.
     
  3. Coolio10

    Coolio10 Registered Member

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    Didn't make a difference.
     
  4. Fiat_Lux

    Fiat_Lux Registered Member

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    From your description it could be one of more things.
    First of all , then though you may be right in this case (or not) then your assumption about your PSU is wrong !!! The fact that some things can get get power is not equal to that the PSU functions as it should , so just to check then trying with a PSU one know for sure is 100% OK would be adviseable.
    Secondly, if not the PSU is then problem could be in either board, CPU or another thing.
    Thirdly , checking things : more things could be "fried" or "broken" , recently I saw a case with a computer where the hardrive failed ("fried") this in turn "fried" both board and PSU so one thing that breaks may take take another with it.
    When checking then I will kindly suggest that you follow the following procedure :
    Remove all cables except for front led,buttons and speaker, remove all cards PCI/PCI-E/AGP/whatever and then start with board + CPU alone (of course with CPU cooler !!!) + RAM you know to be working. Then plug in a PSU you know is OK but don't give it power yet. Put on a cheap working low power Graphics card and connect mouse , keyboard and screen. Check if this works, if it doesn't you may alternate Graphics card from one sitting in the main socket to one in an "old PCI" if you got that kind of socket (beware for settings if you also got onboard graphics, if you got onboard graphics you may try that instead using a graphics card to start with) .
    If neither of this works then either your board or CPU (or both) has a problem , which : you may determin by testing with/on other equipment.
    If the above works then test with different parts until you got the "culprit".
    "Good luck!"
     
    Last edited: Nov 7, 2010
  5. Bill_Bright

    Bill_Bright Registered Member

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    I agree with Fiat_Lux - you need to verify the PSU is working before assuming anything else. The drives use +12V for their mechanical functions, as do fans, but the PSU must also provide +5VDC and +3.3VDC in order for the computer to work. Here is my canned text on testing PSUs:

    To properly and conclusively test a power supply unit (PSU), it must be tested under various realistic "loads" then analyzed for excessive ripple and other anomalies. This is done by a qualified technician using an oscilloscope or power analyzer - sophisticated (and expensive) electronic test equipment requiring special training to operate, and a basic knowledge of electronics theory to understand the results. Therefore, conclusively testing a power supply is done in properly equipped electronic repair facilities.

    Fortunately, there are other options that are almost as good. I keep a FrozenCPU Ultimate PSU Tester in my tool bag when I am "in the field" and don't have a good spare power supply to swap in. While not a certain test, they are better than nothing. The advantage of this model is that it has an LCD readout of the voltage. With an actual voltage readout, you have a better chance of detecting a "failing" PSU, or one barely within specified ATX Form Factor Standard tolerances. Lesser models use LEDs to indicate the voltage is just within some "range". These are less informative, considerably cheaper, but still useful for detecting PSUs that have already "failed". Newegg has several testers to choose from. All these testers contain a "dummy load" to fool the PSU into thinking it is connected to a motherboard, and therefore allows the PSU to power on, if able, without being attached to a motherboard - great for testing fans, but again, it is not a true load or suitable for conclusive testing.

    Note the required voltage tolerance ranges:
    http://i195.photobucket.com/albums/z181/Digerati_Bill/One-Time%20Upload/PSUTolerances.jpg
    NOTE: Disregard the -5VDC reading. It is no longer used.

    Swapping in a known good supply is a tried and true method of troubleshooting used for years, even by pros. If you have access to a suitably sized, spare power supply, carefully remove the suspect supply and replace it with the known good one, and see if the problem goes away.

    I do not recommend using a multimeter to test power supplies. To do it properly, that is, under a realistic load, the voltages on all the pins must be measured while the PSU is attached to the motherboard and the computer powered on. This requires poking (with some considerable force) two hard and sharp, highly conductive meter probes into the main power connector, deep in the heart of the computer. One tiny slip can destroy the motherboard, and everything plugged into it. It is not worth the risk considering most multimeters, like plug-in testers, do not measure, or reveal any unwanted and potentially disruptive AC components to the DC voltages.

    And remember, anything that plugs into the wall can kill. Do not open the power supply's case unless you are a qualified electronics technician. There are NO user serviceable parts inside a power supply. ​
     
  6. midway40

    midway40 Registered Member

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    Coolio, you did not mention the brand of your 'puter. On most Dells the power switch is an indicator which can give you a general idea of what is going on. Green of course everything's ok, flashing amber is usually the PSU, solid amber is mobo related (though it can also be related to an installed card).

    Bill, I got one of those cheap LED PSU testers I use here at work. I am going to talk to the sysadmin about getting one of those FrozenCPU testers. I am now working on a GX520 that was just powering off on it's own though the tester showed the PSU was ok. Apparently after it heats up the PSU would break down.
     
  7. Bill_Bright

    Bill_Bright Registered Member

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    Well, as I noted above, those testers are not conclusive, but are you saying with the PSU plugged into your current tester, the PSU shuts down? If so, then I would definitely suspect the PSU. If you are saying the computer shuts down after it heats up, then I would suspect RAM, the CPU, graphics card (if it has one) or the motherboard board.
     
  8. midway40

    midway40 Registered Member

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    When connected to the tester, it shows the PSU being ok. When I power up the machine for a couple of hours it will shut down with the flashing amber on the power switch. I ran a Dell diagnostic CD beforehand which said that everything checks out ok. I remember working on a GX270 with a similar problem a couple of years ago in which a new PSU fixed it.

    Mobo has no busted caps on it (I haven't seen near as many on the 520s as I have with the 270s) and the HDD checks out. I got a new PSU from Impact Friday but it was defective--only showing 5+V-- so I RMA'd another this morning. I usually keep one on hand but had used it on another 520 earlier last week.

    BTW, I just got approval from the sysadmin to get the FrozenCPU tester so thanks for the head's up on that. :)

    I have cut this short I just got a call from a user saying their screen was 'yellow' :rolleyes: Nobody deserves this much fun :D
     
  9. wat0114

    wat0114 Guest

    I agree with others about the PSU. Just because cd trays open does not necessarily mean it's okay.
     
  10. Meriadoc

    Meriadoc Registered Member

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    Coolio10 have you swapped out your ram to see if that's the culprit. Often one will go and cause the other(s) to also.
     
  11. Fiat_Lux

    Fiat_Lux Registered Member

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    Your problem could possibly still be a recurring periodical fault , I've seen and nailed such, very difficult to go to the shop with for return.
    Only way to find out is : no matter what the test equipment says then try replacing the PSU with a 100% OK and trusted PSU, if that fixed your problem you then had a recurring periodical fault on the other PSU, if it does not fix it then your problem is elsewhere.
    But a computer shutting down can be many things including, but not limited to, defective CPU and not enough cooling of CPU.....
     
  12. midway40

    midway40 Registered Member

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    On Dells I usually get a "thermal event" message and/or a solid amber light when it has a mobo/CPU problem. In this case I was going to replace the PSU and observe the computer a day or so. If it did it again then I would just step back and start over again.

    Since my company has 6 locations with around 150 machines total (aging ones at that, lol) I keep mobos, PSUs, and other items in 'inventory' for a faster turnaround so I do have the luxury of just trying parts out. I don't really like to "shotgun" things but this isn't my primary job and I have limited time to work with them.
     
  13. Coolio10

    Coolio10 Registered Member

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    eMachines with solid hdd light for about 5 seconds.
     
  14. JRViejo

    JRViejo Global Moderator

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    Coolio10, I had an eMachine T2984 that upon reboot, it never came back on. It had a Bestec ATX-250-12E PSU. Tried a new PSU but the Mobo was dead.

    There is an ongoing debate (eMachines Psu Issues) whether it is the PSU or Mobo's fault for the eMachine's issues. Just FYI.
     
  15. midway40

    midway40 Registered Member

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    Ack, some of the stories I read from JR's link are really bad. Someone had to buy another copy of Windows just for replacing a mobo?

    I don't know much about E-machines other than I found out last year they were either bought out by Acer or connected to them. I was setting up new laptops for some employees at work last Christmas (the $198 Walmart specials) and was surprised to see Acer literature in the boxes. I own two Acers and I did replace the PSU in the desktop but it was to upgrade from the stock 270w to 750w to accommodate the 9800GTS vid card I put in it.

    Anyway, good luck with your machine :)
     
  16. midway40

    midway40 Registered Member

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    BTW, someone posted a similar problem as yours on one of the forums that was due to a bad power switch. It appears that E-M used some cheap power switches on some of their models and hopefully that may be your only problem.
     
  17. Coolio10

    Coolio10 Registered Member

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    Put PSU into another emachine (with a dead PSU) and computer booted fine, so i guess motherboard/CPU problem.
     
  18. Noob

    Noob Registered Member

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    That's what i thought at first, CPU or Motherboard :rolleyes:
     
  19. Meriadoc

    Meriadoc Registered Member

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    Have you tried some ram? Maybe to stop all the guessing the best thing would be to take it to your local recommended workshop and ask them for a quote - this will enable you to find out the cause and decide what to do.
     
  20. pidbo

    pidbo Registered Member

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    To me this sound like a bad stick of ram

    unplug your pc

    Try taking one stick of ram out (replug your pc :) )and try to start the computer and then the same thing with the other stick on it's own and if dead ram is the problem you will see which one is the bad stick.

    If you are not familiar with ram it has a small tab at each end holding it into it's slot which you need to release to get it out (remember which way it came out and (when putting it back in again) don't try to put it in back to front)
    It comes out fairly easily so don't force it.

    It usually goes back in (only one way) with a firm even press when the holding tabs are open
    You may feel/hear the ram suddenly click into place when the tabs re-engage.
     
    Last edited: Nov 9, 2010
  21. Fiat_Lux

    Fiat_Lux Registered Member

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    Never wrote that it were the PSU, only that your assumption were not right.
    I agree that, from the experience that others have had with the product you are using, it is most likely a M.B. or CPU problem.
    However the right way to go about things if one wants to trouble shoot in general would be to follow the procedure I described initially.
    For example if you do not follow guidelines as laid out by me then if you put on another CPU that you know is OK on your M.B. and it still does not work you could then logically still not 100% exclude other causes of malfunction unless that you followed the procedure I let you have. Which is to test from the bottom with components you know are working and without any other things connected that might interfer with the outcome of the test that you may perform.

    I see that you understand the important influence a BIOS problem (or wrong data in BIOS) may have on your boards startup procedure, from your writing :
    "I removed the battery but still nothing. I left the battery out for an entire day and it booted up once".
    So I just want to add that after removing the battery (and removing the PSU cable) it generally is enough to just shortcircuit BIOS memory power to drain it by using either contact point on board or by using a jumper, depending on make and model, but usually a few minutes where BIOS power is shortcircut without power will drain memory completely.

    Ohhh... (this remind me) : by the way, strange thing, a few times I've come across where it helped to simply have only the board with no cables other than power button, and no cards (not even video) and memory (can't remember if to leave memory on or not , board othervise totally stripped) , then also strip power cable from PSU to board, remove BIOS battery , remove CPU also !!! , short circuit BIOS power to drain BIOS some minutes, remove short circuit, without CPU then reconnect PSU and turn it on, use power button to give board power, turn off power again, also strip power cable from PSU to board, short circuit BIOS power to drain BIOS some minutes, put on CPU again (+cooler ofcourse) and put back memory on if not on, put on graphics card , attach Video /and turn on screen) , keyboard and mouse, reconnect PSU and turn it on, use power button to give board power and see if this whole, sounding rather elaborate, scheme has worked.
    It will sound as pure nonsense to almost all people but there can seldomly exist conditions on a board within the logic circuitry where the circuitry apparently cannot be reset by other means than the above procedure , this is most likely to work if the root to the problem is some disagreement between the board and the CPU.
    I am not saying that this procedure will fix your problem, but I am sharing my knowledge with you that you can try it out whenever you like if you have a problem.
    I don't care what other people here will say with respect to this procedure, I've had it work on boards that any other would have/had discarded as dead,
    And I do have a 15 year+ experience with "PCs" and have fixed probably houndreds of them (I don't know how many, just countless for me) so I am not new to most of this.
     
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