From: ohg...@gmail.com   
      
   On Friday, July 22, 2022 at 2:06:13 PM UTC-4, Peabody wrote:   
      
   > I'm just not clear how the LEDs are driven. Are they like the old    
   > Christmas tree lights - all in series, so if one burns out they all go    
   > dark? Or are they in parallel, or what?    
      
      
   In *this* model, they're all in series and it's a one channel LED system - one   
   LED or if one interconnect opens, no light.   
      
      
   > Still no success finding a schematic or service manual.   
      
   Samsung doesn't publish schematics anymore.  Just block diagrams and wiring   
   diagrams at best.   
      
   An easy test on this model is to unplug the harness between the main board and   
   the power supply and plug in the AC.   With the main disconnected, the on/off   
   line pull-up resistor will put the power supply into free-run, including the   
   LED drive.  If the    
   back light comes on, the main *or* the power supply board is bad.  If the LEDs   
   come on, post that and I'll walk you through isolating the main or the power   
   supply.   
      
   If the LEDs don't come on with the main disconnected and the AC applied which   
   is what I'm confident you'll find, measure between BD9101 (either side) and   
   J858 on the top side of the board near the LED harness.  Should be more than   
   150V-300V (depending on    
   whether this uses 3V or 6V LEDs) there between those jumpers.  If it's there   
   or higher, the problem is inside the display - either a bad LED or open   
   interconnect between the LED strips.   
      
   No voltage or low voltage between those points?  Bad power supply.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)