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Zenith TV fried from overvoltage A32B41W

Discussion in 'Electronic Repair' started by EJohnson, Apr 8, 2006.

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  1. EJohnson

    EJohnson Guest

    Hello everyone,

    I have a Zenith 32" Model# A32B41W TV that fried from higher inpu
    voltage; someone miswired a receptical and instead of 120 volts the T
    received 240V!!! Lots of smoke filled the living room when the powe
    was restored.

    I took the TV set apart and found two visible blown components...
    1. The line fuse (Alot good this thing did to protect the circui
    board!)
    2. 470uF 200V Electrolytic capacitor "was bloated" (located next to th
    transformer, this is what smoked)

    So I changed those two out with identical replacements...still doesn'
    turn on. I like to try to fix this TV myself...cheap; there are n
    nearby repair shops in my town anyways. Can someone with mor
    experience please tell me what else to look for and test or replace
    What else in the power supply section would burn up from this incident


    Thank you for any help possible;
    Johnso
     
  2. ray13

    ray13 Guest

    Assuming you didn't blow out the new fuse. You have to look for blown
    copper foil paths on the circuit board. Check all the glass and
    epoxy(black case) diodes.Check the value of any resistors that are
    larger than a pencil eraser. There are resistors that act as fuses they
    usually are low ohmic value under 5 ohms for sure and most likely
    factional ohm. I suspect it is a factional ohm resistor that took a hit
    and doesn't show a sign of being blown. You have to use an ohm meter to
    measure them, if they check ok take one lead out and test them to be
    100% sure they are good. Resistors of any size less than one ohm should
    be checked in and around the supply.

    Later
    KC8OJU
    Raymond Borowiak
     
  3. I am not familiar with this chassis...linear or switching supply?

    Tom
     
  4. EJohnson

    EJohnson Guest

    Hello; It is a switching power supply. Board# 9-2003 Date manu. 1998

    I checked the diodes and resistors around the PS section and all appea
    to be fine.
    I remember after I changed the 470uF cap and plugged the TV back in;
    saw a faint puff of smoke rise from somewhere on the board, maybe i
    was electrolytic cap juice left on board from the old cap...anythin
    else that would be affected? Could it be the Power Regulator I
    (STR53041 "5 pin IC") or the HOT (1167-01)? Thanks; Johnso
     
  5. EJohnson

    EJohnson Guest

    A schematic for this board would be useful...where can I get one
    Johnso
     
  6. Jeff, WB8NHV

    Jeff, WB8NHV Guest


    Considering that the set was accidentally plugged into a miswired
    outlet and received much more voltage than it should have, I'd say
    quite a bit of the power supply was damaged or destroyed. I read
    another post in answer to yours that mentioned small resistors that are
    supposed to act as fuses; however, when a TV gets hit with double the
    normal line voltage, no amount of fusing will prevent serious damage.
    I'd get an estimate on repairs first, though. If it is $200 or more,
    I'd put the money into a new set. This may be a good time to look into
    a new plasma or LCD flat panel, unless your set is relatively new. I
    don't know if your warranty, if still in force, would cover something
    like this. If you were not aware that the outlet you plugged the set
    into was miswired (why wasn't a 240-volt receptacle installed rather
    than a standard 120-volt one?) you may have a valid claim.


    Good luck.

    Jeff, WB8NHV (email addy not shown to deter spammers)
    Fairport Harbor, Ohio USA
     
  7. EJohnson

    EJohnson Guest

    It isn't under warranty anymore and the receptical it was plugged int
    used to be 120V but someone screwed up the wiring at a junction bo
    (mixed the neutral with another hot) during a breaker box upgrade.

    I plan to rebuild the power supply section; I just need a schemati
    (free) to know the resistor and cap values. Johnso
     
  8. Guest

    Who is responsible for the miswiring? You--tough luck. A
    professional--luck! It's their responsibility to fix the thing.
    At any rate, it appears you're going to need a pro to fix it. Call
    it quits now.

    David, on the Illinois prairie.
     
  9. Guest

    Who is responsible for the miswiring? You--tough luck. A
    professional--luck! It's their responsibility to fix the thing.
    At any rate, it appears you're going to need a pro to fix it. Call
    it quits now.

    David, on the Illinois prairie.
     
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