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Tough "Dog", Curtis Mathes/Samsung TV model CM27001S

Discussion in 'Electronic Repair' started by Brad, Jun 16, 2007.

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  1. Brad

    Brad Guest

    Hi,

    I have a Curtis Mathes/Samsung TV model CM27001S (mfg. 11/01) in my
    shop. I now have SM (.PDF file)

    The TV will turn on. There is around 27KV (measured) for the CRT. There
    is vertical deflection and good sound, but just as the picture begins to show,
    the TV turns off. Note: This happens every time you turn on the TV.

    Note: Regulated B+ is 130V (measured).

    I unplugged the CRT pcb and the TV stays on. I plugged it back onto the
    CRT and turn "screen" (FBT) to minimum. I turn on the TV and it says on, but
    when I turn up the "screen" slowly, just as the picture begins to show, TV
    turns off. Note: I tested the CRT and it is AOK. If I turn the "screen" all
    the way up, then turn on the TV, I can see a good picture just for moment,
    but the TV turns off. I scoped FBT with "screen" turned all the way down.
    Very good FB pulses which doesn't change at the point the TV turns off
    (by advancing the "screen"). The "Xray" circuit is not the cause (tested).
    I put a "pull up" (via bias box) on the ABL line to "hold up" the voltage
    which would drop (viewed on scope) at the moment the picture starts to show,
    but the TV still turns off.

    Did you have one of these sets with the same symptom? What
    caused it?

    Thanks in advance, Brad

    Before you type your password, credit card number, etc.,
    be sure there is no active keystroke logger (spyware) in your PC.
     
  2. JANA

    JANA Guest

    Check for high ESR caps in the power supply and horiz output stages.

    --

    JANA
    _____


    Hi,

    I have a Curtis Mathes/Samsung TV model CM27001S (mfg. 11/01) in my
    shop. I now have SM (.PDF file)

    The TV will turn on. There is around 27KV (measured) for the CRT. There
    is vertical deflection and good sound, but just as the picture begins to
    show,
    the TV turns off. Note: This happens every time you turn on the TV.

    Note: Regulated B+ is 130V (measured).

    I unplugged the CRT pcb and the TV stays on. I plugged it back onto the
    CRT and turn "screen" (FBT) to minimum. I turn on the TV and it says on,
    but
    when I turn up the "screen" slowly, just as the picture begins to show, TV
    turns off. Note: I tested the CRT and it is AOK. If I turn the "screen"
    all
    the way up, then turn on the TV, I can see a good picture just for moment,
    but the TV turns off. I scoped FBT with "screen" turned all the way down.
    Very good FB pulses which doesn't change at the point the TV turns off
    (by advancing the "screen"). The "Xray" circuit is not the cause (tested).
    I put a "pull up" (via bias box) on the ABL line to "hold up" the voltage
    which would drop (viewed on scope) at the moment the picture starts to show,
    but the TV still turns off.

    Did you have one of these sets with the same symptom? What
    caused it?

    Thanks in advance, Brad

    Before you type your password, credit card number, etc.,
    be sure there is no active keystroke logger (spyware) in your PC.
     
  3. mark

    mark Guest

    How much high voltage does it have maybe it's high,is the screen
    voltage in a normal range or is it excessive.
     
  4. Art

    Art Guest

    Possible LOPT, devices in the G2 supply circuit, and maybe even the Kine,
    even though it may have checked good. The 130 B+ and 27KV uthor potentials
    seem within design tolerence.
     
  5. R!

    R! Guest

    (Brad) wrote in
    Find the monitored leg of the HVT and check there, for a voltage change
    at the time the picture appears.

    Take a closer look at the abl detect is the dag on the tube above ground
    this also may be monitored.

    Hope this helps, been out of this type of work for several years.

    R!!
     
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