Re: Dell W3000 Problem with Power Supply

Discussion in 'Electronic Repair' started by Franc Zabkar, Aug 9, 2008.

  1. Franc Zabkar

    Franc Zabkar Guest

    On Fri, 8 Aug 2008 22:52:43 GMT, put finger to keyboard
    and composed:

    >I thought I had repaired this Dell W3000's power supply , but
    >after about 20-30 minutes the power light goes out (no video or audio)
    >and the power light comes back on (sound and video returns for a sec.).
    >IOW, the power goes off and then back on. Over and over again with a few
    >seconds in between.
    >
    >All the voltages appear to be correct. I'm just not sure if it's the power
    >supply or
    >logic board. I replaced the bridge Rect.(it was shorted), 20N60 Transistor
    >(shorted), Controller IC (shorted). and a couple of
    >Schottky Diodes. This could be heat related.
    >
    >Any help or direction on this would great!!!!
    >
    >TIA


    No specific help, but some general ideas ...

    Assuming the Schottky diodes are on the secondary side, then it might
    pay to see what's connected to those rails.

    Otherwise, if you think the uP may be shutting down the supply, then
    try to locate a PS_ON pin.

    If it's a thermal problem, then try to narrow it down with some spray
    freeze and a hair dryer.

    As a matter of course I'd check the ESR of all the electrolytic caps.

    What is the part number of the PWM controller IC? Perhaps its
    datasheet has an application circuit.

    - Franc Zabkar
    --
    Please remove one 'i' from my address when replying by email.
     
    Franc Zabkar, Aug 9, 2008
    #1
    1. Advertising

  2. Franc Zabkar

    Franc Zabkar Guest

    On Mon, 11 Aug 2008 14:46:34 GMT, put finger to
    keyboard and composed:

    >
    >The primary side controller is a MC33262PG.


    That's a power factor correction controller:

    http://www.onsemi.com/pub_link/Collateral/MC34262-D.PDF

    There must be an additional PWM circuit to drive the chopper
    transistor for the switchmode transformer.

    >Switching MOSFET: 20N60S5
    >
    >The secondary schottky diodes (2): DSSK60-018A 180v 2X30A ...


    Could it be that an excessive load on this particular rail is the root
    cause of your problem?

    - Franc Zabkar
    --
    Please remove one 'i' from my address when replying by email.
     
    Franc Zabkar, Aug 11, 2008
    #2
    1. Advertising

  3. Franc Zabkar

    Franc Zabkar Guest

    On Wed, 13 Aug 2008 14:59:06 GMT, put finger to
    keyboard and composed:

    >It also uses a least one ICE2AS01 controller IC.
    >It may have more, but I don't remember right off.


    That IC has its own internal overload protection but no external
    on/off control. I was wondering whether the PSU had some control pin
    that was being triggered by a fault condition on the logic board. I
    notice that a lot of people are having power-up problems with your
    particular model. One vendor is offering a replacement logic board as
    a solution.

    Here is the datasheet for the PWM controller IC:
    http://datasheet.digchip.com/216/216-12321-0-ICE2AS01.pdf

    - Franc Zabkar
    --
    Please remove one 'i' from my address when replying by email.
     
    Franc Zabkar, Aug 13, 2008
    #3
    1. Advertising

Want to reply to this thread or ask your own question?

It takes just 2 minutes to sign up (and it's free!). Just click the sign up button to choose a username and then you can ask your own questions on the forum.
Similar Threads
  1. Dave97

    How should I filter a Dell sw power supply?

    Dave97, Mar 19, 2006, in forum: Electronic Design
    Replies:
    0
    Views:
    330
    Dave97
    Mar 19, 2006
  2. Brad Curfman
    Replies:
    13
    Views:
    2,260
    Albert Grennock
    Sep 17, 2005
  3. mikercana1
    Replies:
    9
    Views:
    633
  4. Mark

    Dell DJ Dell pocket DJ battery replacement

    Mark, Oct 27, 2007, in forum: Electronic Repair
    Replies:
    0
    Views:
    1,618
  5. Dell W3000 problems

    , Feb 11, 2009, in forum: Electronic Repair
    Replies:
    0
    Views:
    1,039
Loading...

Share This Page