Sharp Acqos LC-40L650X no start but **+%#!!

[maxvalutech]

Due to various reasons haven't looked at any sets for a number of weeks but had a bit of spare time yesterday so decided to take this set back off to test voltages etc. due to no start. Measured between legs of main capacitor on PSU and curses as voltage fluctuating between 180 - 410v. But then checked a connector and a stable 12v found. So been here before as budm knows and he is right that this really can't be so. So watched dmm carefully and noted that now and then battery icon displayed itself. Further checking showed the dmm fluctuations only happened on the high voltages and not on lower ones even on same scale. Now previously I had cross checked with my other dmm and been bamboozled when it also showed fluctuations. But they are both the same make and checking the batteries both are down a bit!!! So both have been giving me false indications but I emphasise only on the high voltages. Live and learn.

[budm]

Re: Sharp Acqos LC-40L650X no start but **+%#!!

When you check the batteries, you need to have load connected.

[maxvalutech]

Re: Sharp Acqos LC-40L650X no start but **+%#!!

Got back to this set finally - have been laid low with heavy cold. The strange wire type connector is P3 with 23 wires and I give details below, the others are CN8 with 9 x Gnd and 5 x 24v all read OK, and the 4 wire is PNL 2 x Gnd and 2 x 12v with nothing shown. Basically as far as i ascertain nothing happens from standby due to error in that no PNL on signal is generated to PSU from mainboard.
PNL ON
BL ON
OFL
ERR. 3.2V
G
G
12V. 12V
12V. 12V
12V. 12V
12V. 12V
G
G
P ON. 2.6V
AC DET. 2.9V
PC3.3. NilV
G
NC
NC
CTRL SEL
KEY1
KEY2. 3.1V
SBY. 3.2V
G

Voltages as shown all else nil reading. Not very familiar at all with this make of set so any input welcome.

[Andrew F. Ali]

Re: Sharp Acqos LC-40L650X no start but **+%#!!

If you have P-ON: 2.9V I would think either the Main Bd. is not sending the PNL-ON and BL-ON signals. The S-BY is 3.2V. Perhaps you could disconnect the connector from PSU to Main Bd. and connect a 1Kohm resistor across the S-BY pin and the P-ON pin, another 1Kohm across S-BY pin and BL-ON pin and a third 1Kohm across S-BY pin and PNL-ON pin and see if the backlights come On and the other voltages appear. If this works then the PSU is OK and we can now investigate the Main Bd.