Power inverter repair question

Discussion in 'General Electronics Chat' started by imaan, Aug 22, 2015.

  1. imaan

    Thread Starter New Member

    Jul 24, 2014
    17
    1
    Hi guys
    I had a 300w Chinese power inverter which due to curiosity I connected it directly to my own build 160w solar panel.
    But it stopped working after a while and now two red and green lights go on together .
    They had used 4pcs of IRF830 MOSFETs which I replaced them
    But there are 2 other MOSFETs on the other side that the place of their code has been scratched !
    So can't see what number those are
    Any idea how to sort it out?
    Or which number is suitable for those two MOSFETs ?

    Regards
     
  2. GopherT

    AAC Fanatic!

    Nov 23, 2012
    5,980
    3,707
    Are they MOSFETS or double high-current diodes?
     
  3. imaan

    Thread Starter New Member

    Jul 24, 2014
    17
    1
    I think out of 6 MOSFET shape pcs there, 4 of them must be MOSFETs and maybe 2 others diodes
    No idea , since the info of those 2 have been faded by the factory !
     
  4. ian field

    Distinguished Member

    Oct 27, 2012
    4,413
    782
    There's usually 2 MOSFETs in a half-bridge configuration. In most cases anything else in TO220 or bigger is diodes, although some older PC-AT PSUs for example had one or two 3-terminal regulators on the secondary side.

    You have to watch out with the rectifiers - they're very often Shottky-barrier type. When testing them, some reverse leakage is normal on the SB variety. A DMM on diode test should easily distinguish between leaky and shorted, fast silicon rectifiers shouldn't show any leakage at all.

    Another thing to watch with SB rectifiers is reverse voltage rating. In AT & ATX PC PSUs, about 45V is fairly typical. Sometimes you might find them rated at 60V, but higher than that they get expensive.

    If it were a flyback type PSU; SB rectifiers on the secondary side would be less likely - but not impossible.
     
  5. #12

    Expert

    Nov 30, 2010
    16,248
    6,744
    Standard stuff: Please post photos and any information about brand name, model number, Users Manual, etc.
     
  6. debe

    Well-Known Member

    Sep 21, 2010
    945
    184
    The 4 x IRF830 are 500v 4.5A MOSFETS, these would be in a H bridge to give the output voltage of the inverter (120V or 240V ). The other 2 IGTBs would be the LV part of the inverter (12v or 24V DC). From personal experience if you hook these inverters just to a solar panel with out a battery to stabilise the voltage. You will destroy the switching MOSFETs/IGTBs.
     
    Last edited: Aug 23, 2015
  7. imaan

    Thread Starter New Member

    Jul 24, 2014
    17
    1
    Thanks for your replies
    Well here is the pic of the board
    I was doubtful about one of the capacitors which will change but still donno which number is suitable for those 2 diodes /mosfets
    Info of the photo:
    On top 4 MOSFETs irf830
    Down is another one and one next to it that I've removed
    Both info is being faded
     
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