Hi, I have been looking though the posts, trying to diagnose the fault with my Vizio D58U-D3. When turned on, the screen remains black. Mistake #1- Never connected an antenna to see if there was any audio. There is nothing displayed on the screen using the flashlight test, but the status light illuminates and goes out. Mistake #2 Never noticed the optical audio out port illuminate until after I repaired the set.
Looking at the power supply board (CAN00), with the TV ON, I never got any voltage on the LED out but the 16 volts to the main board was good.
Occasionally, the set would start working and I quickly tried to get as many voltage readings as possible. This is further complicated with the two (2) ground references between the high and low voltage sides of the board.
Rabbit trail #1: VSNS. I could not figure out if this voltage/signal was generated in the power supply or was coming from someplace else.
Rabbit trail #2: LED power. When the set was working, I had 384V on the lower set of cap's in the high voltage side and when it failed I had 160V (half). The FET's on the underside of the heat sink gave unreliable resistance readings so I decided to replace them. You cannot get the part number (5R380CE-CGJ531) until you pull the entire heat sync. Note: Original FET's are plastic cased, new ones have a metal tab. Be sure and order the bushing and mica insulator kits.
No luck so next I tried the Opto Isolater (L1539 817B) thinking the VSVS signal was not getting back to the FET ‘s.
Still no luck so I followed the trace from VSNS down to the Stunt Regulator (AS431 in a TO-92 package).
After replacing, still no luck.
My friend who had been watching the whole thing had ordered a LED Driver board, so I replaced it, still nothing.
Stepping back, I changed my thinking that something else was controlling the VSNS and retraced the interconnections between all boards (sketch attached.)
In desperation I pulled the Main Bd and went over the board with a microscope and “Et Voila”, there it was. On the CN507, pin 5 was soldered on the bottom of the board but not on the top (where the components live).
With the set working I finished noting all voltages in the power supply for future BadCap'ers (sketch attached).
Hope this helps others.
Looking at the power supply board (CAN00), with the TV ON, I never got any voltage on the LED out but the 16 volts to the main board was good.
Occasionally, the set would start working and I quickly tried to get as many voltage readings as possible. This is further complicated with the two (2) ground references between the high and low voltage sides of the board.
Rabbit trail #1: VSNS. I could not figure out if this voltage/signal was generated in the power supply or was coming from someplace else.
Rabbit trail #2: LED power. When the set was working, I had 384V on the lower set of cap's in the high voltage side and when it failed I had 160V (half). The FET's on the underside of the heat sink gave unreliable resistance readings so I decided to replace them. You cannot get the part number (5R380CE-CGJ531) until you pull the entire heat sync. Note: Original FET's are plastic cased, new ones have a metal tab. Be sure and order the bushing and mica insulator kits.
No luck so next I tried the Opto Isolater (L1539 817B) thinking the VSVS signal was not getting back to the FET ‘s.
Still no luck so I followed the trace from VSNS down to the Stunt Regulator (AS431 in a TO-92 package).
After replacing, still no luck.
My friend who had been watching the whole thing had ordered a LED Driver board, so I replaced it, still nothing.
Stepping back, I changed my thinking that something else was controlling the VSNS and retraced the interconnections between all boards (sketch attached.)
In desperation I pulled the Main Bd and went over the board with a microscope and “Et Voila”, there it was. On the CN507, pin 5 was soldered on the bottom of the board but not on the top (where the components live).
With the set working I finished noting all voltages in the power supply for future BadCap'ers (sketch attached).
Hope this helps others.
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