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1. Thread: Solving electrical circuit - loop method.

by piotrekn95
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3
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2,706

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

You were totally right !

148660

Thanks,

Regards
Peter
2. Thread: Solving electrical circuit - loop method.

by piotrekn95
Replies
3
Views
2,706

[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. Thread: Thevenin's law - tricky example.

by piotrekn95
Replies
11
Views
4,275

[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...
4. Thread: Thevenin's law - tricky example.

by piotrekn95
Replies
11
Views
4,275

[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.
5. Thread: Thevenin's law - tricky example.

by piotrekn95
Replies
11
Views
4,275

[SOLVED]Closed: Re: Thevenin's law - tricky example.

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

by piotrekn95
Replies
11
Views
4,275

[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...

by piotrekn95
Replies
1
Views
1,067

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...
8. Thread: TV LG RZ 29FB51RX no picture.

by piotrekn95
Replies
48
Views
4,956

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. Thread: TV LG RZ 29FB51RX no picture.

by piotrekn95
Replies
48
Views
4,956

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. Thread: TV LG RZ 29FB51RX no picture.

by piotrekn95
Replies
48
Views
4,956

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. Thread: TV LG RZ 29FB51RX no picture.

by piotrekn95
Replies
48
Views
4,956

Closed: Re: TV LG RZ 29FB51RX no picture.

Yes I connected everything.
12. Thread: TV LG RZ 29FB51RX no picture.

by piotrekn95
Replies
48
Views
4,956

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. Thread: TV LG RZ 29FB51RX no picture.

by piotrekn95
Replies
48
Views
4,956

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 ?
14. Thread: TV LG RZ 29FB51RX no picture.

by piotrekn95
Replies
48
Views
4,956

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...
15. Thread: TV LG RZ 29FB51RX no picture.

by piotrekn95
Replies
48
Views
4,956

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. Thread: TV LG RZ 29FB51RX no picture.

by piotrekn95
Replies
48
Views
4,956

Closed: Re: TV LG RZ 29FB51RX no picture.

I checked L102 isnt open.
17. Thread: TV LG RZ 29FB51RX no picture.

by piotrekn95
Replies
48
Views
4,956

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...
18. Thread: TV LG RZ 29FB51RX no picture.

by piotrekn95
Replies
48
Views
4,956

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
19. Thread: TV LG RZ 29FB51RX no picture.

by piotrekn95
Replies
48
Views
4,956

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...
20. Thread: TV LG RZ 29FB51RX no picture.

by piotrekn95
Replies
48
Views
4,956

Closed: Re: TV LG RZ 29FB51RX no picture.

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

by piotrekn95
Replies
48
Views
4,956

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 .
22. Thread: TV LG RZ 29FB51RX no picture.

by piotrekn95
Replies
48
Views
4,956

Closed: Re: TV LG RZ 29FB51RX no picture.

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

by piotrekn95
Replies
48
Views
4,956

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.
24. Thread: TV LG RZ 29FB51RX no picture.

by piotrekn95
Replies
48
Views
4,956

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?
25. Thread: TV LG RZ 29FB51RX no picture.

by piotrekn95
Replies
48
Views
4,956

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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