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Toshiba 27" TV Random Channel 1

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    #1

    Toshiba 27" TV Random Channel 1

    Well this TV is acting up again it has been performing great after the 100uf cap replacement on the vertical IC.

    Lately it has been doing something really strange if I turn the TV off for an extended period and turn it back on the TV won't memorize the last channel it was on and will tune to channel 1.

    Not only that it will sometimes randomly tune to channel 1 while the TV is operating. Not very often but it has happened at least 3 times.

    I understand why it would do it with the TV off if the last channel is not being saved into the EPROM but while the TV is on???

    Anyone ever dealt with something like this before?
    Last edited by Krankshaft; 02-28-2009, 03:43 AM.
    Elements of the past and the future combining to make something not quite as good as either.
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    #2
    Re: Toshiba 27" TV Random Channel 1

    I have seen this on my 25" Hitachi. Does it have an switch for CATV1/CATV2/ANT input select? If it does, check it for dirt. Weird, but that's the problem mine has. Random jump to CH4. Drove me nuts at first, thought the remote had lost its mind.
    veritas odium parit

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      #3
      Re: Toshiba 27" TV Random Channel 1

      This toshiba tv, have notorious solder problem. Go over everything: big resistors, diodes and power transformers and coils. Then replace any capacitors that is looking bad with ESR meter. (required!)

      Cheers, Wizard

      Comment

        #4
        Re: Toshiba 27" TV Random Channel 1

        You were spot on Wizard the caps over the chroma IC were toasted.

        I think I must have replaced at least 15 small value (under 10uf) lytics. They were mostly Rubycon but underrated temperature wise they were 85Cs.

        A light board darkening on the component side of the chroma IC signaled the heat to me.

        I then went over the entire board with my fluorescent magnifier and touched up I don't know how many joints.

        No random changes yet but I'll give it a few days.

        I think I found the source of my intermittant loud HV whine too. A 22 uf 250V cap that supplies the color output transistors through an inductor. It's ESR was around 65 ohms I had to leave it in for the time being until I can order it from Newark though.

        I have had inductors and transformers sing from bad caps before and I'm sure this time is no different.

        That value is too obscure to have in my stock.

        All the caps were Rubycon YK series there were some others I replaced with a big R on them but they were in the minority.

        Also this TV was manufactured by Orion in Taiwan (right again) it said so right on a label on the chassis and on the tube.

        The ESR meter was a must for this one I would be nowhere without it.

        It seems like in low heat areas the 85Cs hold up just fine but in the hotter ones (like over SMT ICs and near heatsinks) they die pretty quickly.
        Last edited by Krankshaft; 04-05-2009, 11:54 AM.
        Elements of the past and the future combining to make something not quite as good as either.

        Comment

          #5
          Re: Toshiba 27" TV Random Channel 1

          Then it is not toshiba. Toshiba is yellow label for toshiba chassis.

          Cheers, Wizard

          Comment

            #6
            Re: Toshiba 27" TV Random Channel 1

            Yikes I have another 32" Toshiba (i.e. Orion here too) it has a white label so I'll assume Orion.

            If I knew this back in 03 I wouldn't have purchased either of them.

            Not a single problem out of it yet though.

            It's the same age as the 27" manufactured in 2003 so I guess they put 105C caps in it since it's still performing flawlessly.
            Last edited by Krankshaft; 04-05-2009, 04:39 PM.
            Elements of the past and the future combining to make something not quite as good as either.

            Comment

              #7
              Re: Toshiba 27" TV Random Channel 1

              Typical.

              Eventually, just get good TV. Avoid generic brands.

              Cheers, Wizard

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