TV power board fuse question

Discussion in 'General Electronics Chat' started by Jrod123, Jan 31, 2016.

  1. Jrod123

    Thread Starter New Member

    Jan 31, 2016
    7
    0
    I have a Vizio E500l-B1 with a Power board ADTV3613XA6

    The problem is I have no power, no lights on in front.

    What I've checked
    120 V out of the outlet
    120V coming into the circuitboard
    But when I check the voltage at the fuse I get almost nothing, but if I remove the fuse and check each end of the fuse holder the voltage is 120v

    With the power plugged in and on the DC side I have the following
    With everything plugged in
    Pic 1
    5.15v
    Empty
    12.3v
    15.5v should be 24v
    Ps_on 2.95v

    Pic 2
    15 volts on each 1234 pins should be 24v

    Not sure where to go from here.
    Any help would be appreciated thank you
     
  2. Jrod123

    Thread Starter New Member

    Jan 31, 2016
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    0
    The fuse is a T5 A/250 and have tested it and put a new one in as well, i'm guessing the board is bad but would like to know why
     
  3. SLK001

    Well-Known Member

    Nov 29, 2011
    821
    229
    You are doing something wrong. If you are removing the fuse and getting 120V on both sides of the holder, then your measurement techniques are in error. Anyway, you are getting output voltages, so the problem isn't the fuse.

    Disconnect the PS from the mainboard and put a resistor between +5 V and PS_ON. This should enable the power supply outputs to be tested. Do this and remeasure the voltages.
     
  4. Jrod123

    Thread Starter New Member

    Jan 31, 2016
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    Yes I understand how mind-boggling it is but how can my technique be wrong? Remove fuse put one lead on each end
    AC mode 125v
    With fuse in nothing, I checked multiple points on each end, One lead on each end

    But back to testing it, by putting a resistor between PS and +5 V do you just mean like a jumper or just take the +5 V wire out of the connector as well as the PS wire out of the connector and then put a resistor in between them and then do the measurements?
    Thanks
     
  5. Jrod123

    Thread Starter New Member

    Jan 31, 2016
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    0
    I put a jumper between 5v and ps_on with the connector off hoping that's what you meant. And had the same ratings +\- .10 while measuring it.
     
  6. Dodgydave

    Distinguished Member

    Jun 22, 2012
    4,999
    745
    The 24V line is down to15v, its an smpsu so something is pulling it down or its not giving it out.
     
  7. Jrod123

    Thread Starter New Member

    Jan 31, 2016
    7
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    What should I test
     
  8. Jrod123

    Thread Starter New Member

    Jan 31, 2016
    7
    0
    The diodes read .57 I think
     
  9. SLK001

    Well-Known Member

    Nov 29, 2011
    821
    229
    I said a resistor. You risk burning out the supply with a jumper. But it has survived this far, so you will probably be okay. So, you are reading the same values with all the cables disconnected but the input 120V? Are any of the TO-220 devices getting hot to the touch? I suspect a bad capacitor on the cold side is loading the 24V supply (but I can't see anything wrong in the pictures).

    What diodes? If it is a schottky diode, the 0.57 is way too high.
     
  10. Jrod123

    Thread Starter New Member

    Jan 31, 2016
    7
    0
    Oops my bad!

    The only one unplugged was the one in the the first pic, not sure if they are getting hot, ill feel next time, that's only on the the DC side right?
    Yes they look schottky diodes
     
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