DIY COMPUTER POWER SUPPLY

Discussion in 'The Projects Forum' started by Ferden, Sep 18, 2014.

  1. Ferden

    Thread Starter New Member

    Sep 18, 2014
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    Hi, my computer crashes very often, and some people told me it could be because of insufficient power. I think it's that, 'cause the PSU is not enough for peak needs. I don't have the money for a new, more powerful one, but I have a spare one.
    Can you use 2 PSU on 1 motherboard by simply providing them both with electricity and connecting both to the motherboard pin-outs?
     
  2. pwdixon

    Member

    Oct 11, 2012
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    Pretty much guarantee that's a bad idea, a PC PSU is not a simple switch mode PSU. Standard switch-mode PSUs often can load-share but a PC PSU is a different beast. I recommend don't do it.
     
  3. Rich2

    Member

    Mar 3, 2014
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    Check the smoothing capacitors with an ESR meter, they are usually the problem
     
  4. Ferden

    Thread Starter New Member

    Sep 18, 2014
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    Wow, I guess it's my fault for posting on such a forum... You see, I don't know what are "smoothing capacitors" or "ESR meter"... I can read on wikipedia, but that doesn't explain me what you mean. Are you saying that instead of increasing the power I should check for a problem in the current PSU's capacitor? And what should I look for exactly?
     
    Last edited: Sep 18, 2014
  5. Rich2

    Member

    Mar 3, 2014
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    Look for electrolytic capacitors on the power supply board they will be something like 1000uf 16v or higher.
    When they are old and faulty they bulge on the top, but not always.
    You would need to unsolder them and get a reading on an ESR meter.

    The ESR meters are about £80
     
  6. pwdixon

    Member

    Oct 11, 2012
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    Of course someone who admits they don't know that much about electronics is not likely to want a meter.

    More likely they just want a solution and at £80 I would imagine you can just buy a replacement/more powerful new PSU.

    Also, if the original PSU has a problem a novice and a broken switch-mode PSU are definitely not a good match and someone is likely to get hurt.
     
  7. sirch2

    Well-Known Member

    Jan 21, 2013
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    Where as a new PSUs are £20 to £30...


    Have you tried just swapping the spare PSU you have with the one in your PC?
     
    atferrari likes this.
  8. MrChips

    Moderator

    Oct 2, 2009
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    The problem might not even be with the power supply. Your mother board could be at fault.
     
  9. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
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    Or one of many other possible problems...
     
  10. sirch2

    Well-Known Member

    Jan 21, 2013
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    I suppose it might help to know if this problem has been going on for a long time or is recent? Is it getting worse? Has anything else changed, e.g. have you installed any new hardware?

    I'd put in the spare PSU, unplug everything but the basics (motherboard, HDD, keyboard, mouse and monitor - preferably on a basic video card) and see if the problem persists and then build up form there.
     
  11. wayneh

    Expert

    Sep 9, 2010
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    There are software utilities that can show you where power is going and what it's being used for. By monitoring the time period before a crash, you might learn where the problem is and what power level triggers it. Whenever my Macbook heats up, I can guarantee I'm going to find Flash burning up lots of power. Force quit that, and everything cools down again.
     
  12. ISB123

    Well-Known Member

    May 21, 2014
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    Some of the components are overheating?Did you check the RAM?Check capacitors on the motherboard?
     
  13. IcedFruits

    Member

    Jan 15, 2014
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    consult a computer repair technician, is it only crashing during high cpu load or just anytime random? ->
     
  14. Ferden

    Thread Starter New Member

    Sep 18, 2014
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    Nah, don't worry: I can pull out a capacitor and weild it back, and I can borrow a multimeter... if anything I would need some info like "the likely problem is this capacitor once had a (hability) of at least (number) (unit of mesure), and now if you mesure less than (number) (unit of mesure) you need to do (action)" I should also know if this mesure has to be done while working or not, while plugged to the PSU or separated.



    Believe me, the one I need is more expensive (at least 130 euros). The thing is I have lot of things on the PC.


    Nope, the second is less powerful.



    I know it could be many things, but the basic hardware (MB, CPU, RAM and video card) is essentially new. I also tried minimal configurations, it's the first thing you do on a diagnostic, and I can't isolate a single piece responsible. Software problems are ruled out.

    On the other hand I made a simple calculation on this website: http://www.extreme.outervision.com/psucalculatorlite.jsp, and the result is clear: not enough watts. Maybe it's my habit of salvage everything, but at the same time I can't really give up the disks or unplug the fans...



    I can't really tell you: I inherited the pc, and as soon as had it I added all my stuff who previously worked fine (that includes my old, more powerful PSU).
    My take is the power. I did want to mesure (not calculate) the consumption, none of the programs I found work:

    http://research.microsoft.com/en-us/downloads/fe9e10c5-5c5b-450c-a674-daf55565f794/ wants I buy and plug a special tool, while

    http://download.cnet.com/Energy-Lens/3010-2077_4-10571141.html wants a specific verion of excel (?!?) to show results

    Maybe someone of you knows a better program (mesuring the consuption at the source is obviously a bad idea, since it's bottlenecked by the PSU limit and implies actually messing with exposed powered household wires)



    I'd really like to know which ones



    Don't think so: after a crash I rebooted and checked the temperature went to the UEFI and on the MB windows utility, and nothing ever went over limits (I think 70 °C is the warning threshold)



    RAM is new (1 year) as for the MB capacitors... I don't even know what they are or what should I look for



    I'm afraid a technician is well beyond my pocket. They also like, you know, to solve any software problem by simply formatting everything whether you have the drivers or not and to solve every hardware problem by selling you whatever surpluss they managed to salvage...
    And yes, a casual use has a crash frequency of 20-60 hours, while network transfer+browser+player+few windows+whatever in the background transform it in 20-60 minutes.
     
  15. pwdixon

    Member

    Oct 11, 2012
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    Last warning. Switch mode PSUs like these if faulty can electrocute you if you touch internal components even after the PSU has been off for a prolonged period. That's all I'm going to say about that, no more posts from me on this. Good luck don't die.
     
  16. #12

    Expert

    Nov 30, 2010
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    I'm used to seeing rows of 2200 uf/16V capacitors on the mother boards (right next to the power plug). Those caps could be bad. I actually fixed one mother board by replacing 8 of those.

    You can pretty much bet that any capacitor of 100 uf or more on the mother board is for power supply filtering.
     
  17. Ferden

    Thread Starter New Member

    Sep 18, 2014
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    You mean they have electricity even when unplugged ?!?



    I don't know man, the MD is less than 1 year old and didn't experience any trauma (fall, short-circuit, humidity, accidental scratch with the screwdriver over the conductive tracks...)

    And I DO lack 150 watts.
     
  18. #12

    Expert

    Nov 30, 2010
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    Yes. A lot of devices can hold a charge after they are unplugged.

    We all suspect capacitors because: A) There was a bad batch of them a few years ago...millions of bad aluminum electrolytic capacitors!
    B) Electrolytic capacitors are the only kind of part that has an end of life calculation when operated under proper conditions.
     
  19. Ferden

    Thread Starter New Member

    Sep 18, 2014
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    Sorry if an ignorant guy questions your degree, but... it cannot be. Not only I opened and touched hundreds of computers and the like without problem, but even if you manage to trap some electrostatic charge, it can't do more than a sparkle. Actually, I never saw that either, not with an electronic devise.

    Well, my PSU is 6 years old...
     
  20. #12

    Expert

    Nov 30, 2010
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    I don't have a college degree in any sort of electronics, but I do have a vivid memory of being knocked backwards out of a television while trying to disconnect the anode connector from the picture tube. Several other devices can retain a charge, but usually not as bad as a CRT.
     
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