+ Post New Thread
Results 1 to 5 of 5
  1. #1
    Full Member level 1
    Points: 2,210, Level: 10
    Achievements:
    7 years registered

    Join Date
    Feb 2010
    Posts
    101
    Helped
    1 / 1
    Points
    2,210
    Level
    10

    Siemens SITOP 20 switch mode powersupply

    Hi friends
    I am try to repair this SMPS Siemens SITOP 20 .
    When I switch on the powersupply Power transistor getting blast.
    I changed all capacitors and faulty componants on control board
    The original powertransistor they used ON5134 and I trieng BUV48A.
    I could not find datasheet of ON5134 . Can I use BUV48A insted of ON5134 ?
    There are two power transistor used as same nomber only one got shorted.

    Thanks
    Maxim

    •   AltAdvertisement

        
       

  2. #2
    Advanced Member level 5
    Points: 34,911, Level: 45
    Achievements:
    7 years registered

    Join Date
    Sep 2008
    Location
    cambridge
    Posts
    7,255
    Helped
    526 / 526
    Points
    34,911
    Level
    45

    Re: Siemens SITOP 20 switch mode powersupply

    You say it bloWs as soon as it switchs on.
    Something bad with the circuit.
    What is gate voltage on fet when you switch it on?

    Is high voltage somehow getting through to your control circuit

    When unplugged and ALL CAPACITORS DISCHARGED....what is resistance bewteen live and neutral.?....or vdd and ground if its not offline psu.

    Be wary of using 10:1 probe on high voltage circuits where you may need 100:1 otherwiwse you blow your scope too.


    1 members found this post helpful.

    •   AltAdvertisement

        
       

  3. #3
    Super Moderator
    Points: 84,086, Level: 70
    Achievements:
    7 years registered
    Awards:
    2nd Helpful Member
    betwixt's Avatar
    Join Date
    Jul 2009
    Location
    Aberdyfi, West Wales, UK
    Posts
    13,835
    Helped
    4593 / 4593
    Points
    84,086
    Level
    70

    Re: Siemens SITOP 20 switch mode powersupply

    I think before even contemplating a replacement you should find out if it is actually a bipolar transistor at all. If it is the main switching device it is more likely to be a MOSFET.
    BUV48A is a BJT.

    Brian.
    PLEASE - no friends requests or private emails, I simply don't have time to reply to them all.
    It's better to share your questions and answers on Edaboard so we can all benefit from each others experiences.


    1 members found this post helpful.

    •   AltAdvertisement

        
       

  4. #4
    Super Moderator
    Points: 15,926, Level: 30
    E-design's Avatar
    Join Date
    Jun 2002
    Posts
    2,014
    Helped
    505 / 505
    Points
    15,926
    Level
    30

    Re: Siemens SITOP 20 switch mode powersupply

    It appears that the recommended equivalent is a BU2508AF. The BUV48A looks like a good match, except for the lower Vce with (Vbe = 0) rating.
    http://pdf1.alldatasheet.com/datashe.../BU2508AF.html


    1 members found this post helpful.

  5. #5
    Advanced Member level 5
    Points: 31,275, Level: 43
    BigBoss's Avatar
    Join Date
    Nov 2001
    Location
    Turkey
    Posts
    4,591
    Helped
    1387 / 1387
    Points
    31,275
    Level
    43

    Re: Siemens SITOP 20 switch mode powersupply

    That transistor can be very old
    800V SILICON NPN TO-3P PHILIPS
    And BUV48A can most probably be an equivalent.


    1 members found this post helpful.

--[[ ]]--