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Sony plasma model PFM42V1 just clicks and buzzes continuing problems

Discussion in 'Electronic Repair' started by [email protected], Mar 18, 2007.

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    I had previously written about this set. There was a "buzzing" sound
    when turn on was attempted. The green front panel light comes on but
    the set doesn't power up. I got into it and found that there is a
    power supply board on the right side. This is where the buzzing seemed
    to be coming from. There is a large heat sink lying flat which is on
    top of what looks like a huge (perhaps 3.0 X 5.0 ") IC. The heat sink
    runs warm.
    There are two voltages marked on a connector on this board. There are
    5.0 volt and 15.0 volt points evident. The 5.0 volts was OK but the
    15.0 volt line was at about 9.0 volts. There was also a capacitor on
    this board, C16. This is a 47uf 250 volt electrolytic which was bulged
    at the top and had unreadable ESR.
    I replaced the cap and the symptoms were the same. Within a minute or
    so the new cap was running quite warm. I powered down and checked all
    the diodes near this cap and they all seemed to be OK. The board was
    reinstalled at this point so I don't know what the voltage across the
    new cap was.
    Since something was going on around the area of that cap my intention
    was to briefly power up again and recheck these voltages. The set was
    powered up for about 20 seconds and I had just finished checking the
    low voltages when I heard a fairly loud "crack" come from the area of
    this board. There was no smell or evidence of any component failure,
    unless its that large IC under the heat sink which I can't really see
    very well.
    The buzzing is now gone and while the 5.0 volt line is still OK, the
    15.0 volt line is now reading 12.0 volts. There are also two small
    fans mounted on two other boards on this set that do not run.
    Admittedly I may be in a little over my head here but I really don't
    want to walk away from this kind of work, especially when these things
    are so expensive and consequently so likely to have a repair estimate
    Can anyone please offer some further assistance with this repair.
    Sorry that this is so long but I don't feel its possible to provide
    too much information when dealing with something like this. Thanks
    very much. Lenny Stein, Barlen Electronics.
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