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Dummy load for SMPS

Discussion in 'Electronic Repair' started by Brian, Nov 25, 2003.

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  1. Brian

    Brian Guest

    I am troubleshooting a SMPS for a projection tv and am not too sure on
    what the load should be. The prints only mention voltages, no loads.
    The schematics show that a +130vdc line is connected to a
    photocoupler, so im assuming this is the line that is used for
    feedback regulation, and therefore the one that needs the load. I have
    looked all over google for "dummy load" and cant really find a good
    site to help me out on this. Any ideas Sam? The sticker on the outside
    of the smps says 120v 150w if that helps.
     
  2. Bill Jr

    Bill Jr Guest

    A 60 watt light bulb makes a near perfect load for the 130 volt line.
    The other section of that power supply doesn't like to be run unloaded, just
    desolder the wire(coil) that supplies the STRS5141G while you test the
    section with the STRS6301.

    Good Luck,
    Bill Jr
     
  3. Brian Friedl

    Brian Friedl Guest

    Okay, you are good. How did you know it was using a STR6301? And the
    other half was a STR5041...you were close. So desolder the supply to the
    transformer or the regulator IC?
     
  4. Brian Friedl

    Brian Friedl Guest

    Even with dummy load, output voltages are all messed up. I have already
    replaced the caps on primary side. Could it be the regulator IC? or the
    Opticoupler?
     
  5. TV Fixer1

    TV Fixer1 Guest

    If output voltages on STR5041 side are bad (high), replace C920,
    [email protected],105c. You'll probably have to replace the vertical IC (LA7838) as
    well, since the runaway B+ to the chip fries it (usually). If the STRS6301
    voltages are high, change C914,[email protected] Too low, change the SE130.
     
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