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Computer won't turn on, help.

Discussion in 'Tech Talk' started by Davegrave, Sep 14, 2011.


  1. Davegrave

    Davegrave
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    I have a Dell Inspiron Desktop computer. Not sure of exact model, I could find out if it matters obviously. Anyway, for the past few week or two it started acting up. Whenever I was away from it for a while and it went into sleep mode it wouldn't start up again when I hit the keyboard or mouse. It was still on with the usual flashing blue light, but just wouldn't "kick in" again. I'd have to turn it off and restart it. I never had a problem with it turning off during use or not restarting. No other problems with it at all. Due to this I have been in the habit of shutting it all the way down when I don't use it.

    Well today, it wouldn't turn back on at all. There's a small green light in back near where the power cord connects. that comes on. But hitting the power button does nothing. No "good" blue light, no "bad" amber light. Just nothing, no fans no whirring. I took the case off to see if it was as simple as a wire not quite connecting in the button region. Was dusty, gave a quick vacuum. fiddled with the connections...still nothing. While the case was off I noticed that in addition to the green power indicator on the back of the unit, there is a light on the main large circuit board that comes on. Yellow/amber in color.

    That's all the info I have. Any ideas? :dunno:
     

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  2. Drjones

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    Are you sure that it was going into sleep mode, or did it actually shut itself off? I suspect the latter, and you're probably looking at a new power supply.

    They are cheap & easy to fix. Don't pay more than $75 for a new power supply, and like 20 minutes to install.
     

  3. Davegrave

    Davegrave
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    Is it something I could do myself? I've put RAM in and replaced a DVD drive. I can detail strip a glock or install a ceiling fan, so I'm "handyish".

    Also, the power button was flashing blue, so I assumed it was in sleep mode. There are no lights visible when it's powered off.
    Also if the power supply is bad would there still be that light visible on the main circuit board when it's plugged in?
     
    #3 Davegrave, Sep 14, 2011
    Last edited: Sep 14, 2011
  4. IndyGunFreak

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    Installing a power supply is very easy.

    Stay away from the "real cheap" ones (my rule of thumb, if it's so light you can throw a touchdown pass w/ it, don't use it).

    Best thing... Get an Antec or a Thermaltake, and you'll probably be OK. Personally, I think $75 is on the low end of what I would spend on a power supply. Do you know how many watts your current power supply is?
     
  5. wrenrj1

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    I'm no tech guru, but did you check your power settings? Perhaps changing the settings so the computer stays on and doesn't go to sleep and see how it acts...
     
  6. havensal

    havensal
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    Try unplugging it and hold the power button down for 10 seconds or so. This drains all of the power and sometime fixes power issues like this.


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  7. Davegrave

    Davegrave
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    I think 350 watts. At least that's what the Dell brand replacement for this model is. Why spend more on a power supply if you don't mind me asking, not being a jerk but I see some reconditioned Dell brand ones for $35. What do the more expensive ones offer?

    Can't adjust power settings. It's won't turn on at all. No reaction to the power button. Unplugged for 20 min. Replugged...still nothing.
     
  8. wrenrj1

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    Yep, sounds like power supply...
     
  9. BarrySDCA

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    sounds like power supply to me.
     
  10. CitizenOfDreams

    CitizenOfDreams
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    One thing you should check before replacing the power supply is the CMOS battery (a small coin cell on the motherboard). Some motherboards do not start if the battery is low.

    Next check is the power supply itself. If you are comfortable with basic electronics, you could disconnect it from the motherboard and short PS_ON signal to the ground (pin 14 on the 20-pin connector or pin 16 on the 24-pin connector). A good power supply will start.
     
    #10 CitizenOfDreams, Sep 14, 2011
    Last edited: Sep 14, 2011
  11. epoxy252

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    You don't need to spend a ton of money for a good power supply, you also don't need to buy a refurbished one with a lesser warranty.

    Here's a sweet 500watt corsair cx 80+ rated for with 10% off of $59.99 and mail in rebate to 49.00 + free shipping. 10% off deal Ends 9/15/11
    Corsair sells some of the best power supplies you can get.
    http://www.newegg.com/Product/Product.aspx?Item=N82E16817139027

    Or a 400 watt Antec Neo Eco 80+ rated for $44.99 + free shipping
    http://www.newegg.com/Product/Product.aspx?Item=N82E16817371029

    Xigmatek 400 watt 80+bronze rated $44.99 + $1.99 shipping
    http://www.newegg.com/Product/Product.aspx?Item=N82E16817815007

    Personally I would stay away from thermaltake's lower end offerings. They are not the same quality/oem as the higher end/cost units.
     
    #11 epoxy252, Sep 14, 2011
    Last edited: Sep 14, 2011
  12. IndyGunFreak

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    Because I've been building computers for about 10-15yrs.. Mostly as a hobbyist, but I've sold a number of them I've built, and Power Supplies is one of those things I've learned you DO NOT cheap out on.

    I don't necessarily mean "spend more"... I mean, my opinion, most of the power supplies in the $75 range, are junk.

    If all you need is 400w, that Antec that Epoxy listed would be a good choice.

    Also, and maybe some of you can correct me on this.. but I worked on a Dell a few years ago, and I could swear it had some sort of proprietary power supply. You need to make sure you have a standard ATX power supply.

    IGF
     
  13. IndyGunFreak

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  14. CitizenOfDreams

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    Yes, I've seen some old Dells (Pentium era) with weird power supplies. Standard 20-pin connector, non-standard pinout. But I think they stopped doing that nonsense. :dunno:
     
  15. Sgt. Schultz

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    That used to be the case but I've found on recent models that they have started using standard connections.


    .
     
  16. GIockGuy24

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    When Dell changed their assembly to China they went to standard power supplies. A friend has one the power supply needed replacing. It was lower end, smaller model.
     
  17. IndyGunFreak

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    That's a relief. I thought that was pretty stupid when I saw it the first time. Of course, if your PS goes bad, Dell will happily sell you a new one for almost half the cost of the PC.. :) (at that time, I don't recall there being an adapter).
     
  18. epoxy252

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    The thing most people don't realize is that there are very few actual PSU manufacturers most of the major brands are actually rebranded units. Like 10 or less if you don't count the no name generic trash.

    The antec that I suggested was actually made by seasonic. The corsair was made by channel well tech. I'm not sure about the xigmatek but I know they were using seasonic,fsp, and sirtech last time I checked. The original dell psu was probably either a seasonic or fsp as they tend to use those two brands for some reason, I'm guessing reliability. All of the ones I suggested have been tested on professional equipment for efficiency, output voltage,active pfc, overload protection, max wattage, ripple etc... They are just as good quality wise as the higher wattage units rebranded and sold for more money. Price and branding are no longer an indicator of quality, as some really expensive psu's from major rebrand labels are dogs.

    Here's an incomplete list of PSU brands and the OEM brand that actualy made them, if anyone is interested.
    http://whirlpool.net.au/wiki/psu_manufacturers

    More complete list and reviews
    http://www.realhardtechx.com/index_archivos/Page541.htm
     
    #18 epoxy252, Sep 15, 2011
    Last edited: Sep 15, 2011
  19. CitizenOfDreams

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    Or, you could extract the pins from the connector and rearrange them in the right order... :whistling:
     
  20. JimmyN

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    You can test the power supply by switching it on manually. If it starts up then it's a motherboard problem or a bad connection in the power_up circuit, if it doesn't start then it's likely the power supply.

    On the 20/24 pin motherboard connector you'll see a green wire, there will only be one, that's your power supply power_up signal line. All ATX power supplies use the same color scheme (ATX specification - version 2.2). It will be pin #16, but you don't have to worry about pin numbers, just look for the green wire.

    The signal line is normally high (3.3V) and if you pull it low (0V) the power supply will turn on. As long as the power supply has line power it outputs on the 3.3V rail even though the computer is off. That's why with the computer off and the power supply fan stopped you may still have some LED's lit up on the motherboard. The power supply is never actually off unless you unplug it from the wall socket, or turn the switch off on the back, if it has a switch.

    Take a small jumper wire, like #24 telephone wire, and stick one end into the back of the motherboard connector so it makes contact with the pin for the green wire. Touch the other end of the jumper to any black wire in the motherboard connector, drive power plug, etc, any black wire will do. If the power supply doesn't switch on, and the fan start running, then most likely the power supply is bad. If it does switch on then either something has failed in the motherboard power_up circuit, or you have a bad connection somewhere.

    ATX power supplies usually won't turn on unless they have a load on the 5V rail. If you pull the connector from the motherboard to test you will likely need to put a resistor or some 12V lamps across a red and black to put some load on the 5V rail. If it's plugged in the motherboard will provide the necessary load.

    If the power supply starts up when you manually ground the green power_up line then you move to step 2. Your motherboard will have a pin header, usually on the lower edge, where the 'power on' switch from the front of the case connects to the motherboard. It will be a two pin connection with two wires, and usually the connector will be labeled 'Power On', 'Power Sw', or something similar. It will be in a group that also includes the 'Reset SW', 'HDD light', 'Power on LED', etc coming from the front of the case. Unplug that connector and momentarily touch a screwdriver tip or something across the two pins on the motherboard to short them together.

    If the power supply again starts up and continues running then the motherboard is good, PS is good, and either the power switch in the case is bad, you have a broken wire, or a bad connection at the pin header. If the power supply started up when grounding the green wire, but doesn't do anything when you short the two 'power on' pins then you have a motherboard problem. If shorting the two pins causes the power supply to turn on, then it turns right back off within a half second then it's not outputting +5V on the power_good line (gray wire), the motherboard is doing a shutdown and turning the PSU off to protect itself from low voltage and you have a bad power supply.

    As always there is a "but" to all of that. If the motherboard is shorted the PS would switch on and back off due to excessive current draw. That would be a bad motherboard rather than a bad PS. I've never actually seen one do that, but it is a possibility since PS's have overcurrent protection. However, any short that would exceed the PS's output current should be noticeable, either by sight or smell.

    So that's my "Power Supply Troubleshooting 101" for Thursday. Maybe there is something in there that will help you diagnose the problem.