Trying to bring this thing back from the dead, and I am new to LCD repair but I have fixed some things before. I am hoping to attempt a component-level repair but I need to narrow down the issue a bit.
This Vizio VT420M (ccfl) was a pawn shop as-is buy: "no sound, HDMI input only". (I don't care about the sound, but it never provided sound from either speaker or output jack. Getting it home, I was able to use all video inputs and even the digital tuning was fine. Score!)
A month later, in the middle of a show, the picture froze and scrambled into the repeated artifacts I have now seen as typical of bad TCon. I restarted the tv and show, and about 30 seconds later the same thing happened. Tried again, and after the freeze, the backlights went and it was done trying.
Symptoms: No backlight, no picture, and (probably) no sound.
My findings are:
In the past, someone had cut/badly patched one set of speaker wires (presumably to check out the sound problem), they may have been shorted somewhere inside their cocoon of elec. tape.
Capacitors look fine. Everything visible looks fine.
Voltage comes out of the PS in its various forms. Standby 5v is fine and logo lights up with power button. PS_on gets 3 volts or so. My 12v is only at 11.4v.
Saw nothing on the flashlight test.
BL_on (labeled O/F on this board) gets 0v. When jumpered to the 5v, the backlights are bright, responsive, and alluring.
LVDS wires test to 0v or 1v, no real power seems to be heading to the TCon. TCon fuse has continuity but shows 0v.
I only found 2 regulators on the main board, one was 5v-3.3v-0v and the other was a fixed ...09 that read 11.4v-0v-9v.
I can provide more details if needed.
So is it the weak 12v of the power board? Or the TCon disabling everything on a whim? Or the main board stepping on the necks of my dreams in unabashed mockery? And where do I splash the solder to make the pictures show up again?
Thanks.
This Vizio VT420M (ccfl) was a pawn shop as-is buy: "no sound, HDMI input only". (I don't care about the sound, but it never provided sound from either speaker or output jack. Getting it home, I was able to use all video inputs and even the digital tuning was fine. Score!)
A month later, in the middle of a show, the picture froze and scrambled into the repeated artifacts I have now seen as typical of bad TCon. I restarted the tv and show, and about 30 seconds later the same thing happened. Tried again, and after the freeze, the backlights went and it was done trying.
Symptoms: No backlight, no picture, and (probably) no sound.
My findings are:
In the past, someone had cut/badly patched one set of speaker wires (presumably to check out the sound problem), they may have been shorted somewhere inside their cocoon of elec. tape.
Capacitors look fine. Everything visible looks fine.
Voltage comes out of the PS in its various forms. Standby 5v is fine and logo lights up with power button. PS_on gets 3 volts or so. My 12v is only at 11.4v.
Saw nothing on the flashlight test.
BL_on (labeled O/F on this board) gets 0v. When jumpered to the 5v, the backlights are bright, responsive, and alluring.
LVDS wires test to 0v or 1v, no real power seems to be heading to the TCon. TCon fuse has continuity but shows 0v.
I only found 2 regulators on the main board, one was 5v-3.3v-0v and the other was a fixed ...09 that read 11.4v-0v-9v.
I can provide more details if needed.
So is it the weak 12v of the power board? Or the TCon disabling everything on a whim? Or the main board stepping on the necks of my dreams in unabashed mockery? And where do I splash the solder to make the pictures show up again?
Thanks.
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