I picked this monitor up as part of my ongoing quest to teach myself electronics. Near as I can tell, it was the victim of a botched repair.
First problem it had, was it would go into standby when power was applied. The vizio logo would light amber, then when you pushed the power button, it would go white. You could hear the power supply kick on, but that was all that would happen. I would then have to unplug it to get it to "turn off." After some google searching I found several threads here about regulators on the mainboard. I tested the u33 LDO which was, in fact, bad. Replaced that:
Then it would power on, and I could get sound. When shining a flashlight through the screen, I could see picture. Ok, backlight time. I cleaned up some horrific soldering botch on both boards, and they are still ugly. Visually the driver chip on the slave board had a pin fried, and I could tell both driver chips had been changed, as they both had flux puddles and pulled up traces. Replaced the driver chip on the slave board, and used a silver pen to re-draw the traces for the driver chips (red boxes in the inverter pics)
Now, the backlight will power on for about 1-2 seconds, then will turn off. The tubes do not look like they are igniting all the way, as the center of the display never comes to full brightness. Still have sound and picture (with flashlight) The HV transformers all test ok on my multi meter, and none of the caps look like they are bad from the outside.
Also, the two heatsinks on the powerboard that are circled in red. They are energized (both when on, and when in standby) with 65v ac. That was a bit of a painful discovery. That cannot be normal right? I do not know if they've always been charged; I only got zapped during testing, after re-installing the inverter boards.
My question is, what should I look at next? Does it sound like bad ccfl's? All the tubes seem to be doing the same thing, and I do not have a spare set of inverters to test with. (unless I could use the darfon board from an insignia I have apart)
P.S. Anyone know what that 4pin ribbon cable by the master inverter board is?(circled in red) There are traces for a plug on the board, but no plug.
First problem it had, was it would go into standby when power was applied. The vizio logo would light amber, then when you pushed the power button, it would go white. You could hear the power supply kick on, but that was all that would happen. I would then have to unplug it to get it to "turn off." After some google searching I found several threads here about regulators on the mainboard. I tested the u33 LDO which was, in fact, bad. Replaced that:
Then it would power on, and I could get sound. When shining a flashlight through the screen, I could see picture. Ok, backlight time. I cleaned up some horrific soldering botch on both boards, and they are still ugly. Visually the driver chip on the slave board had a pin fried, and I could tell both driver chips had been changed, as they both had flux puddles and pulled up traces. Replaced the driver chip on the slave board, and used a silver pen to re-draw the traces for the driver chips (red boxes in the inverter pics)
Now, the backlight will power on for about 1-2 seconds, then will turn off. The tubes do not look like they are igniting all the way, as the center of the display never comes to full brightness. Still have sound and picture (with flashlight) The HV transformers all test ok on my multi meter, and none of the caps look like they are bad from the outside.
Also, the two heatsinks on the powerboard that are circled in red. They are energized (both when on, and when in standby) with 65v ac. That was a bit of a painful discovery. That cannot be normal right? I do not know if they've always been charged; I only got zapped during testing, after re-installing the inverter boards.
My question is, what should I look at next? Does it sound like bad ccfl's? All the tubes seem to be doing the same thing, and I do not have a spare set of inverters to test with. (unless I could use the darfon board from an insignia I have apart)
P.S. Anyone know what that 4pin ribbon cable by the master inverter board is?(circled in red) There are traces for a plug on the board, but no plug.
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