Vizio LED xvt553sv

[mnpdreed]

Re: Vizio LED xvt553sv

On main board in tv now Q1 with meter in diode mode. Black lead on base red on emitter it reads OL. On original main board it read .999v

[budm]

Re: Vizio LED xvt553sv

OK, we used the ground the Gate pin of Q 3 with 100 Ohms and it works, let see if we can use 20K (or any value between 15~20K) to see if we can turn Q3 on. It still does not make sense why Q1 stuck on unless R13 is bad or Q1 is bad.

[mnpdreed]

Re: Vizio LED xvt553sv

R13 on both boards read 9.8K ohms. So replace the 100 ohms with the other correct.

[budm]

Re: Vizio LED xvt553sv

Yes we want to know if 20K or so will be enough to turn on Q3 to provide 12V as before with the 100 Ohm.
If we can get Q1 to toggle high and low then we can use it to turn Q3 on and off, but right now Q1 is not working, we should check the resistance between Collector and Emitter to see if it shows low resistance.

[mnpdreed]

Re: Vizio LED xvt553sv

Board in tv collector to emitter is 11.24K ohms. Original main board has 18M ohms

[budm]

Re: Vizio LED xvt553sv

If it is 11.2K, and R13 is about 9K, then the voltage should be around 1/2 of 12V or about 6V but you are getting 0V (mV range). Something is not making sense unless you should remove Q1 and test it off the board.

[mnpdreed]

Re: Vizio LED xvt553sv

Tv came on with 20K ohms connected

[mnpdreed]

Re: Vizio LED xvt553sv

It had 4.8 volts on the gate of Q3 and same on Q1 collector 27mV with new resistor connected

[mnpdreed]

Re: Vizio LED xvt553sv

Can you test it in curcuit first just to get an idea. If so how