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LG Plasma TV;50PC51-ZB;Chassis:LP78A(B) PP78A (B);no picture an OSD;Sound ok

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Sven76225:
Hello,

I am a television engineer and need help.

 :sign0085:

A 50PC51-ZB TV television stands on my desk.

PDP Model : PDP50X40D46


Mistake:

- No picture and no OSD insertions
- Sound available

A visual examination was carried out.

The front LED shines after him switch on permanently green. The screen is getting light for half a second. It appear, on top on the right in the corner to letter. However, these are very difficult to recognise.Complete screen black.

The operating voltages VA, VS, 5 V, 3.3 V exist. The fan works. On the 50X4A_CTAL_256 board all SMD DIODES SMD shine except D1 and D2. These diodes are nearby to IC 101.

I measure on the power board

Plug P800 ( See appendix ) Picture 1

The voltage 3.4V_ON is higher. The voltage value is 4,48 V. Where the voltage is generated. Have a bad circuit diagramm. From it this is not award.  :03:

On the signal processor Board (board name : 50X4A_CTAL_256CH Patr No : EAX37080201    REV : F) is an oscillator (see figure appendix). On the signal processor Board is an oscillator (see figure appendix) I measure To the resistor (R51) 3.3 volts!

I measure to the voltage converter, unfortunately only 5 V and 3.3 V. Where I measure 1,8 V and 2,5V? I need a better circuit diagramm. Please !

Thanks for your help.I wish a nice weekend.

Greeting Sven

Turnip:
Hi Sven 76225,

No ideas, never met one, no manual, but feel should reply as had a good and sunny week-end, and your entry was the ideal - full details, circuit info and piccies - who could ask fer more.

No Basil Fawlty stuff - local folks,

Now to try make some cash - Chris.

Sven76225:
Hello Chris,

thanks you for your answer.  :08: I have clamped the modules. (Buffer Modul´s upper and lower). One after the other! Upper and lower picture half is not shown. View check of the modules was unobtrusive! No dark places obviously. I have added the appendix some picture. The first picture shows the Y-Wavefrom. Unfortunately, not correctly.  :41: (The Probes have the setting 10:1) (DC voltage = -2,30)
What I could still test?

Regards, Sven

Turnip:
Hi again Sven,

Sounds like one for our very own 'Brian the Brain' as it's slightly more technical than double-dipped Conkers - Bri's speciality, that none but our 'Sparky' can comprehend  - Chris.

PS - Admit it's a taste aquired - or perhaps not.

michael first:
Hi Sven,
it could be a psu problem but as you know the diagram is not available.anyway take a look at the manual,can get some ideas.Cheers. 

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