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eMachine power supply (PSU) green light flashing, won't turn on

By Augy
Nov 29, 2010
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  1. My sister-in-law has an eMachine that she turned off and unplugged before leaving for vacation. A week later she returned and plugged it back in only to find it won't turn on. I don't know much about this pc other than it's a tower and about 3 or so years old. I figured it was probably the PSU (power supply) but wanted to verify as many things as possible. Basically, there is a green light on the back of the pc (on the PSU) that will flashes on and off when you try to turn on the computer. The PSU fan doesn't spin and nothing else makes any attempt to turn...just dead.

    I pulled all the power connectors and jumpered the power switch pins (15-16), this gave me a solid green light on the PSU and the fan spun normally. I tested with a voltmeter and got the proper voltage on all the pins. I am thinking that this probably rules out the PSU but not 100% as something could be 'pulling it down'???

    Any ideas on what else to look at? I hate to buy a PSU when it appears this one is ok. That pretty much leaves the MoBo and/or CPU. I've pulled all the cards and memory trying to get it to do anything and nothing affects it. I suspect there is something wrong with the MoBo but don't know how to verify that.

    Any help or advice is appreciated. Thanks!
     
  2. Computerpete

    Computerpete TS Rookie Posts: 151

    What you need is a PSU Tester which you can get on eBay that will tell you if the power supply is bad.
     
  3. Computerpete

    Computerpete TS Rookie Posts: 151

  4. Augy

    Augy TS Rookie Topic Starter

    Do those testers put a 'load' on the PSU? I tested all the voltages and they were what I would expect but that wasn't under any sort of load. Probably worth picking one of these up though since they're so cheap. Thanks.
     
  5. captaincranky

    captaincranky TechSpot Addict Posts: 10,823   +922

    Emachines have a nasty habit of motherboards going bad. Examine the area around the CPU to see if there are any bulging or burnt capacitors.

    The voltages from a PSU are present more than once in the main harness. I'm not sure if all,say 12 volt lead come off the same tap.

    Is the HDD spinning up?
     
  6. Augy

    Augy TS Rookie Topic Starter

    Thanks, I'll examine the caps tomorrow morning. The HDD is not spinning. If I have everything hooked up (i.e., the power harness from the PSU to the MoBo), I get nothing but a blinking green light on the PSU and another blinking green light on the MoBo. No fans spins, nothing at all. The best I can do is to jump the power switch pins (15-16) on the harness and then I get the PSU fan to spin and the voltages all appear.

    I'll check the caps and post back...thanks again!
     
  7. Computerpete

    Computerpete TS Rookie Posts: 151

    What the testers do is test that power is coming through if the psu is working properly the lights will show up green.
     
  8. Computerpete

    Computerpete TS Rookie Posts: 151

    Hi augy
    If you are getting a tester I would get the Dr Power one looks good.
     
  9. Augy

    Augy TS Rookie Topic Starter

    Well, I took the PSU into a local PC shop and they tested it with an 'analog' tester (which I assume is like the cheaper ones on ebay). They said it tested ok. So, I figured it must be the MoBo or CPU. Since it's about 4 years old I figured it was probably worth upgrading and just bought a new Mobo/CPU and memory. Got home and swapped out the components and went to fire it up and....same thing, blinking light on PSU. Arghhhh!

    So now I figure it has to be either the PSU or the on/off switch. I tested the switch the other day as well and it seemed ok. I hate throwing good money after bad but it looks like I'll have to try a cheap case/psu and (hopefully) be done with it.

    I don't what else it could be. New MoBo, CPU, RAM, and HDD with old Case and PSU gives me the same blinking light. It HAS to be either the PSU or the case, right??? Man, I get frustrated when it's MY computer and MY money but when it's someone else's I just feel awful. I've got a buddy with a case/psu laying around that I'm going to borrow and see if that fixes it. Wish me luck!
     
  10. Augy

    Augy TS Rookie Topic Starter

    Got a used but working PSU and case from a friend. That solved the problem. So, I guess it was either a flaky Power Supply or power switch. Won't know for sure unless I want to investigate further but at this point I'm just happy to have it up and running.
     
  11. Xqu_sme

    Xqu_sme TS Rookie

    Hello I the same problem with the blinking green light, I wanted to know if could use a PSU from a hP a6700y for a e machine t3646? I know that the difference between the two isn't much but I don't want to blow the mobo. PLEASE ANY INFO WILL BE GREATLY APPRECIATED.
     
     
  12. captaincranky

    captaincranky TechSpot Addict Posts: 10,823   +922

    An off the rack eMachine should be able to accept any spec ATX 2.0, 2.1, or 2.2 PSU, within reason. The size of the case kind of limits you to maybe a 400 watt max PSU. Larger supplies are too deep.

    OK, a PSU puts out 3 or 4 different voltages, 12.0+, 5.5+, 3.3+, and IIRC a 12.0-. Any of those taps could have failed. Basically, the system fans run on 12 V + along with the optical drive motors, the USB on 5 V+, and the CPU gets stepped down off the 3.3 V+ tap. (There is a measured CPU voltage on the order of 1.0 to 1.5 Volts +. I'm not exactly sure if this is another tap off the PSU, or the mobo's VRM performs the step down).

    As for the PSU in the Hewlett, if it is a Matx case, and the PSU sports the ATX standards I quoted above on its back plate, then most likely, yes.

    (The "ATX" standard includes the mounting flange dimension, and bolt spacing spec, as well as the specific voltages).

    At most, a suitable brand new replacement for the eMachine, should cost no more than $50.00. Since the age and mileage of the HP PSU starts to become an issue in an of itself, as who knows when that is going to give up the ghost, a brand new supply would be your best option in the long run.

    BTW, you should verify that none of the capacitors in proximity to the CPU are burnt, blistered, or bleeding, before you undertake this as a strictly PSU failure. It could be the motherboard.

    But generally speaking, a failure to revive from soft off, is the PSU.
     
    Last edited: Aug 1, 2014


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