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Sony KV36FS12 no power any thoughts

Discussion in 'Electronic Repair' started by bob, Oct 20, 2007.

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  1. bob

    bob Guest

    My neighbor has a Sony Wega set that just went dead and asked me to look at
    it
    completely dead no response to remote or power button
    Wondering if these have any known issues that I need be aware of that might
    cause this
    Thanks
    bob
     
  2. AJ

    AJ Guest

    Check the obvious, then call for service. Multiple things may cause a dead
    set, including being unpluged, having a blown fuse, or other failures. Post
    any actual diagnostics and tests that have been done then a revelant
    responce may follow.
     
  3. Guest

    Many of the later model Sony TV's have a built in Self- Diagnosis
    function. If the timer/standby indicator is blinking, this could be an
    indication of the problem with the unit. The diagnostic blinking will
    occur automatically with no action required by you to engage it.
    The timing of the blinking you see would be as follows: two to eight
    blinks (depending on the fault) about a third of a second apart, then
    pauses for 3 seconds, then the two to eight blinks about a third of a
    second apart again. Here is a list of the problems that might have
    occurred indicated by the number of blinks. The words in parentheses
    are those which you will see for each of these faults on a diagnosis
    screen described later in this article. Unit is dead and there are no
    blinks---Problem in the standby power section. Might check fuse, R607,
    Q601, IC601, R612 and VDR601 (should show open)
    Continuous Blink Once A Second, No Pausing---No reply from the jungle
    IC (data bus is busy, shorted to ground or held high), IK video path
    is defective.
    ONE Blink--- not used for the self-diagnosis
    TWO Blinks---B+ over current protection (OCP) , unit goes to the
    standby mode then displays the 2 blink fault. Could be a short in the
    power supply of any of the circuits.
    THREE Blinks---B+ over voltage protection (OVP), unit goes to the
    standby mode then displays the 3 blink fault. This is also a problem
    in the power supply circuit.
    FOUR Blinks---No Vert. Deflection (V STOP), Screen goes to a single
    horizontal line then the video signal muted.
    FIVE Blinks---AKB circuit (AKB), the timer/standby indicator blinks
    for about 30 seconds then goes to the self-diagnosis function.
    Something is wrong with the video. Also unit be in IK blanking, try
    turning up screen slightly.
    SIX Blinks---No Horizontal (H STOP), no raster, goes to the blinking
    selfdiagnosis function immediately. Check jungle IC and nearby
    components.
    SEVEN Blinks---High voltage shutdown. The high voltage has exceeded
    33kv and the unit goes immediately into safety shutdown. Check power
    supply regulation and horizontal circuits.
    EIGHT Blinks---Problem with the audio (AUDIO), unit goes to standby
    and blinks the self-diagnosis code. Check audio amp IC.

    faisal :)
     
  4. bob

    bob Guest

    By Dead I should have clarified that there is nothing no diagnostic lights
    blinking or otherwise so I Assume loss of a DC supply and hoped for some
    common issue causing this I'll reply when I get into it
    Bob
     
  5. James Sweet

    James Sweet Guest

    For a completely dead set I'd start in two places. First check the fuse, if
    it's blown then figure out why. If the fuse is ok, then check for standby
    voltage. Unfortunately I have no direct experience with this model though.
     
  6. Jerry G.

    Jerry G. Guest

    Start with the basics:

    Is the set plugged in to the AC?
    Are there any blown fuses?
    Is there anything looking visualy burned?

    When any of the above faults are shown, this means that there is a more
    serious problem that must be delt with.

    If you have the experience and a good DVM and a scope, start by getting
    the service manual, and then following through from the power supply.
    There are many types of failures that can cause a set to fail according
    to your description.

    Your best bet is to pack the set in to the car, and bring it to a local
    service center that is able to service Sony TV sets. These sets can
    be a challange for even the most experienced techs.

    There are also safety issues involved when performing TV service.


    --

    Jerry G.


    By Dead I should have clarified that there is nothing no diagnostic
    lights
    blinking or otherwise so I Assume loss of a DC supply and hoped for some
    common issue causing this I'll reply when I get into it
    Bob
     
  7. yeah there is one usr error get a life or a g f instead of posting
    stupid retarded question u pathetic sad loser.
     

  8. he did ask u to take it to a repair center he asked u to fix his
    neibbhor t.v. for him u pathateic sad troll loser retard.
     
  9. Bob T

    Bob T Guest

    I got this opened up last night and the 6.3A fuse was blown
    Luckily this PS is removable and I brought it back to my bench to look for
    the problem
    After checking all the obvious things and finding nothing bad I replaced the
    fuse and powered it up without incident then proceeded to bypass the two
    relays to bring up the running voltages again without incident.
    I'm going to put it back in tonight and start looking elsewhere .
    I'm assuming the HOT would be the next likely place to check . Any other
    obvious places to look
    Seemed strange that with this diagnostic capability a non PS problem could
    take out the primary fuse.
    Bob
     
  10. Actually, the fuse would not normally blow on a Sony when the horizontal
    output is shorted. The SMPS transistors and fusible resistor however, would.

    I'd check the horizontal transistor of course, but if the bridge rectifier
    is OK, and the main input DC filter cap doesn't show a short across it, I
    would guess the fuse was the only problem - just try firing it up and see. A
    fuse is easier and faster at this stage than troubleshooting more. You can
    resume troubleshooting if the fuse blows again. Do remember to resolder the
    horizontal drive transformer and the vertical output I.C. for good measure.
    BTW the horizontal transistor will show a near-short emitter-base when
    measured in-circuit. This is normal.

    Mark Z.
     
  11. Bob T

    Bob T Guest

    Went back out and checked the HOT an dit was fine but as you said very low
    resistance in circuit

    Having checked out the Hot I gave it a try and it ran fine just a blown
    fuse.

    Friend commented that they were jumping around in the room the night before
    it failed

    Thanks again

    BOb
     
  12. AJ

    AJ Guest

    Another common falure in a lot of large screen direct view sets (i.e. >27"
    diag measure) is the degauss thermistor changing value causing increase
    current during degauss functions. Eventually it will cause the 6.3 amp fuse
    to simply open. RCA, Samsung, Sony, Philips, etc have all incurred this
    specific symptom called "nusiance Fuse failure".
    Repairs normally involve changing the fuse and degauss thermistor, plus
    resoldering the LOPT, H drive transformer, H-output, etc.
     
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