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TV powers down

First TV would not come on and I found power supply PW8552 had vented electrolytic caps C840 and C841, R820 burned open in darkened area of PCB, and blown F807.

I found suggestion to replace caps C840, C841, C822, R820, Q840 (L787MR05) and Q802 (STR-D1005), all in darkened area of PCB to fix symptom of TV would not come on.

Now TV comes on but powers off after 5 or so minutes. It will come back on when I pull the plug and reinsert it.

Any ideas where to check next? I know this is an old TV, but I have come so close, I just want to finish fixing this problem.

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  • Larry Copley Jan 26, 2008

    Sorry, my first post, and I thought I filled in somewhere that this is a Toshiba rear projection model TP5288 with Toshiba Chassis TAC8891 (shared by 46 inch model TP4688) and the Power Supply board is PW8552 which is the board the component references are from.



  • Larry Copley Jan 27, 2008

    After replacing Q802 and Q840 (I think these were the regulators because they each had five pins) The relay clicks on and the TV comes on right away, and works great for about five minutes. Then the relay clicks off. It comes back on again without using the power button by power cycling the plug i. e. I un plug the set and then plug it back in and it comes on by itself.



    I read somewhere there are Chemical Fuses on the board and I was kinda thinking maybe the Chemical Fuses reset themselves when I cycle the power.

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  • Master
  • 8,617 Answers

What is the make and model number of the set your trying to repair? Post that information and I will be able to possibly help you out.

Posted on Jan 25, 2008

  • 1 more comment 
  • Sonny Berry
    Sonny Berry Jan 26, 2008

    When you power up your set whart does t do?

    Do you hear the relay click? Have you checked the voltage regulators all of them? Usually in sets that have that many shorted components I always check all regulators as well as check for shorted line coils and leaky diodes in the Bridge rectifier.

  • Sonny Berry
    Sonny Berry Jan 26, 2008

    Also if you dont have any success you may want to call PTS they usually stock all the modules for thousands of models at about 30 percent of what the OEM prices here is a link.

    http://www.ptscorp.com/

  • Sonny Berry
    Sonny Berry Jan 27, 2008

    Yo have a resistor or diode that must be open. Check near the regulators that you replaced. What is happening is the resistor is probaly allowing a rise in voltage and thats tripping the shutdown mode if it cycles off fast enough your set can power back on when you replug it. I am not famillar with chemical fuses. However toshiba does use fusible resistor FR and variable resistorsVR. I will do some research on that chassis. Check the resistors near those regulators take one lead out of circuit to check them.

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