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Need suggestions repairing PSU

Discussion in 'General Hardware' started by grandpatzer, Nov 27, 2013.

  1. SaiZo

    SaiZo

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    Just out of curiosity - what brand/make and model is your PSU? Can't find that information.
     
  2. grandpatzer New Member

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  3. grandpatzer New Member

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  4. de.das.dude

    de.das.dude Pro Indian Modder

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    :s going by the thread, i see that you lack experience in working with electronic components....

    the first thing you should have done to "fix" the loosening of the green pcb is to take a small wattage needle pointed soldering iron and touch the point where the green pcb was mounted. that would have reflowed the solder and eliminated any cracks..

    you have to be pretty clumsy while fitting it all back to not notice that the fan was too big and was hitting the pcb. nothig much can be done at this point, hope it works without that component.

    i just read that you failed at soldering it and that you melted the component itself,.... so its impossible to even know what the component was....

    if you knew what it was, its possible to fix it back with some delicate insulated copper wire and very intrinsic soldering. but that would require someone with a lot of practice and steady hands.


    this doesnt pertain anyway to the topic, but i dont like those temp adjustable expensive ones. those are really for the uber elite class of people who solder day and night. the prob is they are high wattage usually and will maintain the tip at specified temp as constantly as possible. no problems when soldering continously/heavy stuff, but when it comes to delicate stuff like small LEDs, SMD components, thermally sensitive components etc, they are bad. For that type of applications a good 10 -15W iron does the job good for amateurs as it can only transfer a "fixed" amount of heat to the component before cooling down itself :p hence preventing melt down of delicates (pun intended)
     
    Last edited: Dec 3, 2013
  5. grandpatzer New Member

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    you clearly lack any reading comprehension but anyway thanks for trolling me :p
     
    itsakjt says thanks.
  6. SaiZo

    SaiZo

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    You could always try the last solution.. Not even sure it will work.. Take a picture of the PCB where the SMD was, and send it to rwlabs, and ask them the specs for the component.
    If I knew what to look for, the chances of me having the same component would be 50/50 - but you would get it for free (could have sent it by mail).

    I know those are tricky to solder, I have done it once or twice, last time was on an Opticon device. Not only do you need steady hands, but get something that can magnify when you are soldering the component.
    For this reason, I have several soldering irons. Two of them are electrical, 175w & 30w and the third one uses butane. I bought extra tips for that one, just so I can make them as tiny and "sharp" as possible.

    Usually I glue them on first so that something is holding it. Then I solder the "feet" to the PCB. Oh, and get one of them "helping hands" with a magnifier, might not look like much but they are great.

    Good luck!
     
  7. grandpatzer New Member

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    On another forum a user thinks the LG is label for Toshiba, 2SC2712, according this manual the G stands for DC current gain hFE.
    Toshiba datasheet

    In that case I think a BC846 Transistor might be correct?
    There is 3 transistors on Elfa, difference are 330mW, 250mW powerdissipation, and marking is Marking 1B, Marking 1B* , Marking 1Bs
    Infineon sold on Elfa NXP sold on Elfa Diotec sold on Elfa


    One problem is that it has 65v while the toshiba is 50v, not sure if that is problem?
     
  8. grandpatzer New Member

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    So on another forum a user suggested me a transistor which seems like he knew was the correct one.
    Are these correct steps for me now?

    I have ordered the transistor, I should have it nextweek for soldering :)

    I want to be sure to have tested as good as I can before installing my PC components to the PSU, so besides these steps are there others to take?

    1: Solder and assemble PSU
    2: plug into wall PSU and with multimeter measure ATX 24pin Black + Purple, result should be between 4.75 and 5.25V
    3: Measure Yellow and Black, should get 12v
    4. Red and Black 5V
    5. Orange and Black 3,3V
    6. Install a fan and harddrive to PSU see if they start.
    7. install PSU into PC?
     
  9. SKBARON

    SKBARON

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    If you have any old pc parts you don't mind losing, test the psu on those, if anything goes wrong at least you won't fry your system. But it should work alright after you solder that sucker back in place :).
     
  10. grandpatzer New Member

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    thanks that makes sense, Phaedrus suggested me the transistor, he was not 100% sure about it,
    however
    I know he knows about psu's so I'm hoping he's correct about the transistor.
    I have ordered the transistor should have it next week.

    post17 regarding the transistor:
    http://www.jonnyguru.com/forums/showthread.php?t=11159&page=2

    So I guess the multimeter measurements and attaching a harddrive to is a good start?
     
  11. SKBARON

    SKBARON

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    Yes, those test are a good start, just use a spare or old hdd :), you seriously don't want any surprises.
     
  12. grandpatzer New Member

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    I finally recieved the transistor and soldered it in, bad news seems when I measure with multimeter I'm not able to get correct readings... only Black purple gives me good readings:
    Black Purple: 5.17v on level 20v on multimeter.

    Black Red on level 2000m: 0019
    Black Red on level 20v: -0.02

    Orange black level 200m: 00.5

    I also measured Green Black I believe that one was 4.79.
     
  13. xorbe

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    I've been watching this thread with interest, and I'm generally all for DIY fixes, but in this instance, you might not really want to go repairing a power supply without proper knowledge, due to danger of fire.
     
  14. johnspack

    johnspack

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    I hope there was not too much stress placed on the pcb when this happened, there could be breaks in traces in levels you can't see. Sorry, just glanced at this thread, normally I'd just chuck it out and start again. If you're sure it's just a top layer component, then go for it.
     
  15. grandpatzer New Member

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    My soldering tip is a bit too big for this job, it took me long time to solder it, I might remove the transistor and hopefuly it works without it there.

    Also I think the transistor is not same as the old one because it's physicaly much smaller...
     

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