Hi.
Am getting too old. Cannot find the schematic section for the backlight drivers in a 50LN5400 service manual.
----> [ https://servlib.com/lg/tv/50ln5400-ta-50ln542y-tc-chassis-lb36b.html ]
Unit does not turn on backlights; a flashlight against the screen shows video. The connector "+led" and "-led" for the backlights is dual; like two sets of drivers. "+ led" referred to chassis shows 80V at each branch; "+led" referred to "-led" shows no voltage. [P801 at top edge, near left on image]
If I had a known healthy string of LED backlights I could rule out the supply by plugging and confirming; but not.
If I knew the healthy voltages at the backlight connector pins, I could rule out things too.
If the two mosfets are not doing the grounding path at the schematic below; well that would match symptom.
Guidance, please ?
Am getting too old. Cannot find the schematic section for the backlight drivers in a 50LN5400 service manual.
----> [ https://servlib.com/lg/tv/50ln5400-ta-50ln542y-tc-chassis-lb36b.html ]
Unit does not turn on backlights; a flashlight against the screen shows video. The connector "+led" and "-led" for the backlights is dual; like two sets of drivers. "+ led" referred to chassis shows 80V at each branch; "+led" referred to "-led" shows no voltage. [P801 at top edge, near left on image]
If I had a known healthy string of LED backlights I could rule out the supply by plugging and confirming; but not.
If I knew the healthy voltages at the backlight connector pins, I could rule out things too.
If the two mosfets are not doing the grounding path at the schematic below; well that would match symptom.
Guidance, please ?