July 14, 2022, 10:39 AM
snideraTV / Electronics repair gurus, some help please
TV croaked during a thunderstorm. Plugged into a wall surge suppressor, 3 other devices on same are OK. Replaced it with a larger, 4k set for less money than I spent in 2016, so I'm not sad.
Vizio M552i-b2
No power-on light. No 5V stand-by on power board, no reaction to power button or remote. Googline wasn't specific help.
On the power board, I found 2 diodes that are shorted & 5 capacitors that read open (possibly due to diodes? at least the electrolytics are right next to the diodes)
Mosfets all pass diode test from source to drain.
It's a grand total of $3 for the parts, before the $8 shipping from mouser.
I can't track down 1 diode part number exactly. The larger one in the bottom left of picture. The marking is (from polarity stripe) "LT4" new line "SB2". no mfg mark that I can see & none of the mouser brands list that type of mark. Probably a chinesium substitute...
LT4 translates best to the STmicro
SB2 translates best to the Vishay
Both are 60V Schotkty diodes, so I'm going to buy both & try the bigger Amps 1st.
Sound like a plan? Any advice? I'm little more than 'don't let the magic smoke out' with electronics, so any advice/experience could help.
52216208664_ee00d031f1_o by
Andy Snider, on Flickr
mouser by
Andy Snider, on Flickr
July 14, 2022, 11:02 AM
SpinZoneTroubleshooting circuit cards can be challenging. If you are not isolating components you may be getting erroneous readings. Repairing circuit boards without causing additional damage is skill in itself.
That being said, go for it. Its already broke, you can't make it work less.
Is this what you need?
Not A Recommendation For This Particular SiteJuly 14, 2022, 12:06 PM
snideraquote:
Originally posted by SpinZone:
Troubleshooting circuit cards can be challenging. If you are not isolating components you may be getting erroneous readings. Repairing circuit boards without causing additional damage is skill in itself.
That being said, go for it. Its already broke, you can't make it work less.
Is this what you need?
Not A Recommendation For This Particular Site
That picture isn't the same, but $60-70 is the going rate for the power boards.
I'm thinking more along the lines of 'Swap $10 of parts in & see if it works'. There's always the chance there is something fried downstream, so I'm not dropping $70 to find out the main board ($100, but out of stock) is cooked too.
The shorted diodes could be the cause, could be a symptom.
I will probably pull the parts I identified off to test them before ordering new ones, but the caps are cheap & easy to replace, so I'll swap them too.