Overloaded Toshiba TV (2010)

Discussion in 'The Projects Forum' started by jesserebel, Nov 19, 2013.

  1. jesserebel

    Thread Starter New Member

    Nov 19, 2013
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    RE: Toshiba 26" TV/DVD Model #26CV100U / Doesn't come on & no lights at all

    Greetings,

    My father managed to cross some wires while working in the house circuit panel and now my daughters TV doesn't work at all (sent 240v through the outlet we think).

    A friend who works at Radio Shack pulled out the Power Supply Unit (photos attached) and we determined that the ceramic fuse in the bottom left-hand corner is blown ... though after reading many threads here I'm not sure if that is the entire problem.

    My friend builds radios so he can handle the soldering on the boards but he doesn't work on TVs so he said that I have to do the research.

    This board runs about $80 but unfortunately it isn't available that I can find.

    Would anyone be kind enough to give me their assessment on this? Will swapping out that fuse solve the problem?

    ... thanks in advance. :)
     
  2. shteii01

    AAC Fanatic!

    Feb 19, 2010
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    Replace the fuse. It is there to protect the circuit. If it is blown, then it did its job and the circuit is most likely in working condition. Replace the fuse and it is likely that the circuit will work, and tv will work.

    The fuse rating is probably printed on the board next to it. For example, I am looking at the power board from lcd monitor, the rating for the fuse is printed on the board right next to the fuse.

    In the first photo I can see it is rated for 4 ampere current. The second number is 250 volts, but it does not say AC or DC. Also there are a couple of other parameters missing. You might want to e-mail Toshiba and ask them for specs on this fuse.
     
    Last edited: Nov 19, 2013
  3. jesserebel

    Thread Starter New Member

    Nov 19, 2013
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    Thanks for your quick reply shteii01!

    We found the fuses locally for $3 (for 5) so we will be swapping it out very soon.

    My biggest concern was if that current was passed through the Neutral side then there is no fuse to protect that, or is there?

    Anyway, will post back as soon as I have the new fuse soldered in.

    Thanks! :)
     
  4. wayneh

    Expert

    Sep 9, 2010
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    I'm a little less optimistic but agree completely with the advice. You can't proceed one way or the other until you replace the fuse.
     
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  5. #12

    Expert

    Nov 30, 2010
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    That fuse is between the jack labeled L and N and a 220 volt capacitor, so I'm betting it's an AC fuse. Besides, there is no reason to put a 250 volt fuse on a 24 volt DC circuit. Speaking of betting..are you willing to bet $3 you can repair the TV? If so, buy the fuses. You will be betting a lot more than $3 if you take it to a repair shop, and the third answer is the trash can.
     
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  6. shteii01

    AAC Fanatic!

    Feb 19, 2010
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    I also think it is 250V AC fuse, but mine is clearly labeled so. Their's just says 250V, so I was not sure.
     
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  7. jesserebel

    Thread Starter New Member

    Nov 19, 2013
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    Hello again ... and thanks for the responses.

    I got the electronics shop to solder a new fuse on the power board for me (only $10) but sadly it didn't solve the problem.

    I put it all back together and plugged it in. I heard the familiar "click" like it was coming on and then nothing. Took it apart again and the fuse was blown again.

    The repair shop wants me to bring the entire TV in so I guess that is next. I found that power board on eBay for $80, so maybe take a chance on that?

    Any thoughts?
     
  8. #12

    Expert

    Nov 30, 2010
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    The last time I did this, the click meant the horizontal output transistor had shorted. ANYTHING can be taking out the power supply fuse.
    If you don't have skills and test equipment, make a decision between price of repairs and price of a different TV.
     
  9. wayneh

    Expert

    Sep 9, 2010
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    And even if you do, there's no guarantee of success. The only guarantee is that it will take a lot of your time. If you enjoy the challenge and can be patient waiting for parts and such, go for it. Personally, I've replaced the HOT and a number of other components - still no joy on my TV project.
     
  10. MaxHeadRoom

    Expert

    Jul 18, 2013
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    You have 5 power devices on the board, 3 of them in the area marked primary, any of these devices would be suspect, Personally I would opt for the 3 on the pri. section first.
    Max.
     
  11. shteii01

    AAC Fanatic!

    Feb 19, 2010
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    It looks like I was too optimistic.
     
  12. wayneh

    Expert

    Sep 9, 2010
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    Have you searched for a schematic or service manual?
     
  13. debe

    Well-Known Member

    Sep 21, 2010
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    The first to check is the mains rectifier then the 2 switching devices on the head sink for shorts.
     
  14. THE_RB

    AAC Fanatic!

    Feb 11, 2008
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    The main PSU FET is likely blown (shorted). It (they) are on the small heatsink at the top, in the "primary" zone.

    You should also check the diode bridge (black rectangle above the big primary cap). It may have a shorted diode.
     
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