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Philips Widescreen TV EM1.2UAA / 30PW850H37A

Discussion in 'Electronic Repair' started by Archon, Sep 11, 2008.

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  1. Archon

    Archon Guest

    Hi , any TV repair folks help out here.

    This widescreen TV had a flashover, took out the red output on the
    TDA6108JF Video Output Amp on the crt board.

    I bought replacement chip and fitted it, now instead of a bright red
    screen with flyback lines I get a very bright white screen reduced in
    size with flyback lines.

    Previously I had Vin of 2.8Vdc, Vout(Cathode) 139Vdc on the dud chip
    (remaining working parts)
    Now I have 0.8Vdc input and 18Vdc output (Cathodes)

    Black current measurement output pin 5 old chip 0.8Vdc, new chip 7.5Vdc

    I don't have a schematic, any ideas where to buy ? I'm not in the TV
    servicing business anymore, prefer watching them than fixing them but
    this is my own TV and I guess I have to fix the sucker.

    I don't see any adjustments in this set, is there anything I need to do
    to set up/ recalibrate the black level? Isn't this automatic on these
    fangled new sets? Is the new chip duff? It did arrive in a polybag,
    guess its not that static sensitive. Nothing else reads as out of spec
    and using the duff chip, disabling the red output and shorting the red
    and green cathodes at the tube gives a reasonable picture.

    TIA for any help,

  2. Archon

    Archon Guest

    OK, No matter, fixed it, new chip was duff, wtf, lucky I ordered 2.
  3. Graz

    Graz Guest

    Are duff chips a common problem? I recently bought a frame output
    chip for a Hitachi TV that was shorted across two pins.
  4. Jerry G.

    Jerry G. Guest

    In looking ahead, to answer your question I myself have had bad IC's
    that were new.

    Because the drive IC had to be changed, it would be a good idea to see
    if there is anything unusual that could have caused it to fail in the
    first place. I have had everything from a CRT that arcs intermittantly
    to components becoming defective in the circuit area that works with
    the IC.

    Jerry G.
  5. Archon

    Archon Guest

    For parts to be defective from new is unbelievable, this was a Philips
    part made in Thailand from a reputable parts dealer. Where is the
    quality control? God help us when they start making chips in china.

    From researching this fault on the web it seems this tube/tv has a
    history of flashovers and early tube failure. Flashovers usually occur
    when switching from cable input to component video. In fact this is the
    third flashover that I have seen (heard) on this, the chip surviving the
    previous two.
    I have seen modification bulletins for other brands using the TDA6108JF
    involving extra earth bonding between the CRT board and aquadag/tube
    bonding but on this crt board the amount of ground copper is almost nil.
    In fact the board is of such poor quality the tracks lift as soon as
    they see an iron, very bad for Philips but typical of the decline in
    quality of domestic electronics, one reason I got out of the TV/video
    repair scene in the late 80's and went to medical/test equipment
    servicing where quality was still in evidence.
  6. Archon

    Archon Guest

    In the field I work in now, test equipment/medical no, but domestic
    repairs I couldn't say. I did replace the Lopt in a projection TV along
    with all the associated stuff that fails with it and that lasted only 12
    months where the previous had run for 10 years without problem. That got
    binned, just couldn't be bothered with it.
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