sharp lc40le820e, il televisore rimane spento, non accende

[riccoricco]

Good evening. The TV, as per the title, was completely turned off at a voltage test on the power supply board marked "DPS-126CP" known that the 13 volt output of the "Q7911" appears but not on the "C7962" the 5 volt and present a light hissing from the card in question, I try to close contact 3 and 4 of the optocoupler location "pc7702" and I am pleased to note that the screen lights up even if it is white and the 12 volt that feeds the "T-CON" also appears in the part where the sensor controls appear remains off after a few seconds the TV switches off. I decide to replace the optocoupler mentioned together with the other three and I am pleased to note that now the sensor controls part lights up even if no flashing appears, the TV behaves as before with the exception of the sensors part which lights up as explained. closing pins 3 and 4 of the optocoupler mentioned, again the situation repeats that starts with the blank screen. The power supply of the optocoupler location "pc7702" is 9 volts, I think it is excessive as if there was no absorption by the integrated "ic7702 dda003a" but maybe I'm wrong. I try to follow the "AC_DET" line that refers to pin 9 of the "p9601" connector must be at a high level and in fact 3 volts appear, at pins 1,2,3,4, 13 volts appear and pin 11 i 5 volts.

[kasfamily]

Re: sharp lc40le820e, il televisore rimane spento, non accende

Hello!
Power supply circuit
Ciao!
Schema di alimentazione

[peterkos2]

Re: sharp lc40le820e, il televisore rimane spento, non accende

Good day.
Can you advise me on the problem?
The TV Sharp mentioned above to the owner recently worked by turning itself off after three hours of watching, and then repeating it over and over again after 20 minutes.
But now it cannot be switched on and the logo in the middle flashes twice at intervals. According to the service manual, this is a fault in the power supply board. After the measurement, I found that the PD connector was missing 13.2V.
On Q7911 the SOURCE is fluctuating 14.2-14.35V
on DRAIN is 0V
at GATE is 14.19-14.38V
Thank you for any advice

[dick_barton]

Re: sharp lc40le820e, il televisore rimane spento, non accende

On the schematic check what voltage you have at SW because it looks like the mosfet Q7911 is not being turned on.
Can you give the voltages on Q7921 and Q7061

[Davi.p]

Re: sharp lc40le820e, il televisore rimane spento, non accende

No good hijack others one's thread.