I have a Vizio V042L. It's about 4 years old, and I had one inverter board replaced by a local repair shop about a year ago when it exhibited the same symptoms as these threads:
https://www.badcaps.net/forum/showthread.php?t=14667
https://www.badcaps.net/forum/showthread.php?t=18010
Now it's happening again: no picture, but all other functions in tact, including audio, but my problem seems different from those other threads (hence the new thread).
When I plug the set into the wall, the Vizio logo illuminates orange. When I press the power button, the Vizio logo illuminates white, but no picture. I tried the flashlight test, and can't see if there's any picture there at all, but there's definitely no backlight. About 2 seconds after powering on the set, a blue LED illuminates quickly on the master inverter board. After about 1 second, it slowly fades to dark over the course of another second.
So far, it seems the same as the other threads, right?
The devil's in the details here. I think my problem is different. Read on for the exciting ending!
After reading the very helpful information on those threads (and a few others), I began troubleshooting the set.
Here's what I found:
GOOD: Power supplies appear okay. 5v standby voltages are good when turned off, and all voltages are good when turned on. No capacitors appear puffed or smoked. The ICs and leads look good on each inverter board, but I graciously defer to the more masterful eyes on this forum to review my photos (attached, hopefully high enough resolution).
BAD: I measured the resistance across each of the 8 MOSFETs, 4 per inverter board. At least, I believe these are MOSFETs--please correct me if I'm mistaken. They all read 8.5 Kohm, except one MOSFET on the slave inverter board (circled in red), which reads in the 10s of Ohms (seems way too low compared to the other 7).
So I am suspecting this one MOSFET (circled in red).
My question to you, oh great masters of Badcaps:
I have soldering experience, and this looks within my ability (the IC looks a lot harder by comparison).
Thank you in advance for lending your time and expertise.
https://www.badcaps.net/forum/showthread.php?t=14667
https://www.badcaps.net/forum/showthread.php?t=18010
Now it's happening again: no picture, but all other functions in tact, including audio, but my problem seems different from those other threads (hence the new thread).
When I plug the set into the wall, the Vizio logo illuminates orange. When I press the power button, the Vizio logo illuminates white, but no picture. I tried the flashlight test, and can't see if there's any picture there at all, but there's definitely no backlight. About 2 seconds after powering on the set, a blue LED illuminates quickly on the master inverter board. After about 1 second, it slowly fades to dark over the course of another second.
So far, it seems the same as the other threads, right?
The devil's in the details here. I think my problem is different. Read on for the exciting ending!
After reading the very helpful information on those threads (and a few others), I began troubleshooting the set.
Here's what I found:
GOOD: Power supplies appear okay. 5v standby voltages are good when turned off, and all voltages are good when turned on. No capacitors appear puffed or smoked. The ICs and leads look good on each inverter board, but I graciously defer to the more masterful eyes on this forum to review my photos (attached, hopefully high enough resolution).
BAD: I measured the resistance across each of the 8 MOSFETs, 4 per inverter board. At least, I believe these are MOSFETs--please correct me if I'm mistaken. They all read 8.5 Kohm, except one MOSFET on the slave inverter board (circled in red), which reads in the 10s of Ohms (seems way too low compared to the other 7).
So I am suspecting this one MOSFET (circled in red).
My question to you, oh great masters of Badcaps:
- Am I on the right track in diagnosing this problem?
- If so, can this MOSFET be replaced?
- My inverter boards are marked as Rev 1.2. Should I just buy 1.3 replacements anyway?
I have soldering experience, and this looks within my ability (the IC looks a lot harder by comparison).
Thank you in advance for lending your time and expertise.
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