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Sony KV-T25SZ8 TV problem

Discussion in 'Electronic Repair' started by David, Dec 14, 2005.

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  1. David

    David Guest

    Hi All,

    I'm about to start working on the above model - apparently it stopped
    working after a lightning storm. The tv has no standby lights, but you can
    hear it momentarily "thump" when the power point is first turned on. I'm
    guessing that the main capacitor is still charging - the fuse is still
    intact.

    Does anyone have any ideas on where to start first. I'm guessing I'll have
    to get a manual to start tracing.

    Any thoughts would be greatly appreciated.

    David
     
  2. kip

    kip Guest

    Yes trouble shoot the SMPS section first.

    kip
     
  3. Bruce H

    Bruce H Guest

    Agreed. I have found that in a SMPS that a power surge can take out
    ceramic disc caps in the power supply. Sometimes they are hard to see as
    they don't fail like electrolytics.

    Bruce
     
  4. David

    David Guest

    Many thanks for your reply.

    How do I check ceramic disc caps without an ESR meter?
     
  5. sofie

    sofie Guest

    David:
    Use a DMM to check for shorts or leakage and if your DMM has a capacitance
    function you can measure the accuracy of the disc cap for the proper
    value....
    Not to be condescending here but are you certain you have the necessary
    electronics experience and knowledge to be working on one of the most
    dangerous electronic devices in your home????
    For lots of helpful information regarding repairs and troubleshooting you
    should go to the website for this newsgroup at
    http://www.repairfaq.org/
    plan to spend some quality search time there.
    --
    Best Regards,
    Daniel Sofie
    Electronics Supply & Repair
    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    - - - - - - - - - --
     

  6. Why do you want to? Ceramics don't change ESR as they age.
     
  7. David

    David Guest

    I finally got around to having a look at the set today. I found a ceramic
    capacitor on the AC (next to a 470 ohm resistor) side that was open circuit.

    The capacitor is marked 103P. Am I right in assuming that it is a 130 pF ??
     
  8. Asimov

    Asimov Guest

    "David" bravely wrote to "All" (08 Jan 06 09:25:07)
    --- on the heady topic of "Re: Sony KV-T25SZ8 TV problem"

    Da> From: "David" <>
    Da> Xref: core-easynews sci.electronics.repair:354497

    Da> I finally got around to having a look at the set today. I found a
    Da> ceramic capacitor on the AC (next to a 470 ohm resistor) side that was
    Da> open circuit.
    Da> The capacitor is marked 103P. Am I right in assuming that it is a 130
    Da> pF ??


    That cap is probably not 130pF.
    Capacitors are normally open circuit for DC, what do you mean by this?

    The marking 103 would mean 10 with 3 zeros, so this would mean it was
    a 10,000pF or a 0,01uF capacitor. However the letter P is a tolerance
    of +100/-0% so the cap may measure as much as 0,02uF. Finally, its
    thickness and diameter would give a rough approximation of its voltage
    rating, unless it is written.

    Typically, P tolerance 0,01uF or 0,1uF ceramic caps are used for
    bypassing and this means these would be unlikely to cause a major
    problem if they did fail with a reduced capacitance.

    A*s*i*m*o*v

    .... High Voltage Electronics: Life's a glitch, then you fry.
     
  9. David

    David Guest


    I tested the capacitor and it measured -.598 on the 2uF range on my
    meter. I'm wondering if my meter is stuffed.
     
  10. Asimov

    Asimov Guest

    "David" bravely wrote to "All" (09 Jan 06 09:26:11)
    --- on the heady topic of "Re: Sony KV-T25SZ8 TV problem"

    Da> From: "David" <>
    Da> Xref: core-easynews sci.electronics.repair:354617

    Da> I tested the capacitor and it measured -.598 on the 2uF range on
    Da> my meter. I'm wondering if my meter is stuffed.


    If the cap was across a diode it might be rectifying the test signal
    and resulting in a negative reading. First try unsoldering just one
    leg and then take the measurement.

    A*s*i*m*o*v
     
  11. David

    David Guest


    I tested the cap out of the circuit initally. I'm wondering if my meter is
    on the way out.
     
  12. Asimov

    Asimov Guest

    "David" bravely wrote to "All" (10 Jan 06 06:56:16)
    --- on the heady topic of "Re: Sony KV-T25SZ8 TV problem"

    Da> From: "David" <>
    Da> Xref: core-easynews sci.electronics.repair:354740


    Da> I tested the cap out of the circuit initally. I'm wondering if my
    Da> meter is on the way out.


    If the cap tested open circuit on the DC ohms range then I certainly
    would wonder about the capacitance range since caps don't typically
    exhibit a negative value.

    A*s*i*m*o*v
     
  13. David

    David Guest

    What DC ohms range could I expect from this capacitor?
     
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