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  1. Replies
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    [SOLVED]Closed: Re: Solving electrical circuit - loop method.

    You were totally right !

    I used your advices and solved:

    148660

    Thanks,

    Regards
    Peter
  2. Replies
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    [SOLVED]Closed: Solving electrical circuit - loop method.

    Hello everyone,

    I've been trying to solve this circuit :

    148604


    Just to be clear -the single circle with arrow means voltage source,
    - double circle with arrow...
  3. Replies
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    [SOLVED]Closed: Re: Thevenin's law - tricky example.

    Ok, I know what i should do with resistors. But now, for example I want to calculate the Thevenin's voltage on A B terminals. Is it possible to use the node potential method ?
    It will be a problem...
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    [SOLVED]Closed: Re: Thevenin's law - tricky example.

    147668

    What do you think about that? Could it be correct? Of course Ra, Rb, Rc will be calculated from triangle/star formulas.
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    [SOLVED]Closed: Re: Thevenin's law - tricky example.

    It's just the symbol which are used at my university to draw a "voltage source".
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    [SOLVED]Closed: Thevenin's law - tricky example.

    Hello everyone,

    I've been trying to solve this circuit. I have to use Thevenin's method to find the I5 current - so I tried to calculate the Thevenin's voltage and Thevenin resistance.

    I tried...
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    Closed: Solving nonsteady circuits.

    Hello,

    I am preparing for my circuit theory. I am trying now to solve a basic circuit like this :

    131798

    I know that I could use Laplace theory to do it (with s symbol).
    But unfortunately...
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    Closed: Re: TV LG RZ 29FB51RX no picture.

    1) Gate of Q401 has 8V.
    2) Resistor R407 has 67,5V
    3) B+ has 134,6V
    4) pin 32 od sda5555 has 3,3V

    - - - Updated - - -

    drain of mosfet has 0,1V, source =0V
  9. Replies
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    Closed: Re: TV LG RZ 29FB51RX no picture.

    There is 0V, also 0V on R421.

    Do you think it could be KIA4558 or transistor broken?

    - - - Updated - - -

    Also 0V on C416.
  10. Replies
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    Closed: Re: TV LG RZ 29FB51RX no picture.

    You're genius.

    I checked d413 diode and there is 0V. I'm going to check that diode outside fbt.
  11. Replies
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    Closed: Re: TV LG RZ 29FB51RX no picture.

    Yes I connected everything.
  12. Replies
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    Closed: Re: TV LG RZ 29FB51RX no picture.

    OK, I was checking for bad soldering. And I check the voltage again. I've got +3,3V on pin 44. But there is still no picture.
    But tv isn't going to standby, it's working, but no picture, filament no...
  13. Replies
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    Closed: Re: TV LG RZ 29FB51RX no picture.

    It's a sound like a starting TV .

    TV won't start if pin 44 has 0,45V ?
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    Closed: Re: TV LG RZ 29FB51RX no picture.

    OK, I connect like in schematic.

    TV now is starting on, hearing coil. But there is still no picture. Even the filament is not glowing.

    Maybe it's something with Horizontal/Vertical...
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    Closed: Re: TV LG RZ 29FB51RX no picture.

    OK, if I understood, I should connect through resistor r40 the output of IC to ground?

    Cheers
  16. Replies
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    Closed: Re: TV LG RZ 29FB51RX no picture.

    I checked L102 isnt open.
  17. Replies
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    Closed: Re: TV LG RZ 29FB51RX no picture.

    Well, I checked voltages, and look:

    pin9 =2,46V
    pin11=3,29V
    pin13=2,46V
    pin30=3,28V
    pin33=3,29V
    pin37=2,45 (It should be 2,7V so there is voltage drop)
    pin42=2,46V
    pin44= there is a...
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    Closed: Re: TV LG RZ 29FB51RX no picture.

    Question is - could I check these voltages when tv is in standby mode?|


    ps. sorry for not being on forum but studying, studying :D
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    Closed: Re: TV LG RZ 29FB51RX no picture.

    I replaced LM7845, but nothing helped.

    nnaveli - what do you mean remove standby pin ? It's about SDA 5555 IC or DDP 3315 ?
    Could I removed this standby pin, and tv should switch on even if the...
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    Closed: Re: TV LG RZ 29FB51RX no picture.

    Ok, I will check the voltages.
  21. Replies
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    Closed: Re: TV LG RZ 29FB51RX no picture.

    I removed this two resistors but tv still going back to standby. I'm still thinking about la7845 .
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    Closed: Re: TV LG RZ 29FB51RX no picture.

    I disconnected yoke connector but tv is still going to stand by.
  23. Replies
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    Closed: Re: TV LG RZ 29FB51RX no picture.

    I checked in darkness, and you're right. When I power on tv the filament is glowing for a few seconds and tv is turning back to stand-by.
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    Closed: Re: TV LG RZ 29FB51RX no picture.

    I checked LA7845 and on the 6th pinount is only 12,3V not 14. Could be a defected ic?
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    Closed: Re: TV LG RZ 29FB51RX no picture.

    I checked B+ and it has 134.5 V. So fbt is working correctly?
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