PSU Asus. Is the bridge rectifier dead? Need advices for replacement

Discussion in 'Power Electronics' started by UnnamedUser159, Aug 2, 2016.

  1. UnnamedUser159

    Thread Starter Member

    May 3, 2016
    130
    0
    Hi there.
    I began the thread in one other forum, but cannot remember the password init(have done "forgotten password" but still am waiting for mail..?)
    I am giving you the URL with photos.
    https://www.flickr.com/photos/142883181@N04/sets/72157671570689715/
    The product model is t6kb60 0024
    First - is it dead?
    Can you give me advices which parameters to watch as main?
    I want to find a replacement because the price for that in Ebay is not cheap and the psu doesn`t cost that price. To not comment the time in weeks,months.
    Want to buy replacement here from Bulgaria.
    I can tell you what bridge on that voltages there are here in the stores.
    I see Repetitive peak reverse voltage 600V.
    I am ataching One photo!

    Thanks in advance

    the main meaning is to learn something and second perhaps sell it at very low price.
     
  2. wayneh

    Expert

    Sep 9, 2010
    12,151
    3,058
    We are to guess from a few photos? Have you made any measurements?
    Do you have any experience diagnosing a power supply? It could be dangerous to poke around inside if you don't know what you are doing.
     
  3. Dr.killjoy

    Well-Known Member

    Apr 28, 2013
    1,190
    156
    @wayneh
    +1

    I am not sure what info you need in choosing a bridge rectifier.. A bridge rectifier doesn't change the voltage or current unless you count the diode voltage.. It simply adaptes AC to DC but make sure you won't go past the Max voltage and it can handle the current needed..
     
  4. AlbertHall

    Well-Known Member

    Jun 4, 2014
    1,961
    387
    As has been said we would need our psychic powers to be much enhanced to be able to answer that.
    On the right side of the picture, by the blue wire, there are two components in black sleeves. Looking down the top of the sleeves, one of them looks orange and one of them looks black. This is the same in both pictures. If that component really is black inside it is probably dead. Was the fuse blown?
     
  5. UnnamedUser159

    Thread Starter Member

    May 3, 2016
    130
    0
    i can`t see glass fuse.
    Yes, i am talking about the different color on the physical view of the element.
    What voltage should i see on what "pins" of the bridge ?
     
  6. wayneh

    Expert

    Sep 9, 2010
    12,151
    3,058
    The inner two pins should be at your local AC supply voltage. I suppose that's ~220V AC?

    The outer two pins (labelled + and -) should show a DC voltage between the AC value above and ~1.4X that value, so ~220-308V DC. It's probably toward the higher end due to the presence of a filter capacitor. You might find that same high voltage on the pins of one of those large blue electrolytic capacitors.

    You can also check the DC voltage on each outer pin against either of the AC pins. Sometimes a damaged bridge will show one side working and not the other.

    I'm assuming that the transformer in the picture is not changing the incoming voltage, and that the rectifier is rectifying mains voltages. I'm not sure of that.
     
  7. AlbertHall

    Well-Known Member

    Jun 4, 2014
    1,961
    387
    The 'transformer' is a simple inductor (you will notice just two wires) and is part of the circuitry to correct the power factor of the supply.
    If it has active power factor correction (PFC) then the PFC circuit is connected between the bridge and the bulk storage capacitors and the bridge output will be mostly unsmoothed rectified mains.
     
  8. ian field

    Distinguished Member

    Oct 27, 2012
    4,415
    784
    For a 230VRMS supply; you'd expect the reservoir electrolytic to charge to somewhere around 320VDC - its dangerous because neither side of the cap is ground.

    PFC front ends are a common weak spot - but that one has a dirty great iron-cored choke in series with the AC feed instead.

    If the bridge rectifier fails; it usually takes out the fuse - it can be either glass or ceramic, sometimes wire ended types are covered by heat shrink tubing.

    Any time a PC PSU is opened; is a good excuse to inspect the secondary side electrolytics, Any with bulged (or sunken) tops should be replaces with good quality low ESR parts.
     
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