Element ELCHS321 has 5vsb and red light but wont turn on

[triplefour]

Re: Element ELCHS321 has 5vsb and red light but wont turn on

so i was trying to measure these smt components as best i can. the o resistor checks out at 0, the 2 ceramic caps on the left check out around 14-15kohms each but the resistor labeled 105 (whats that supposed to mean?)
and the ceramic cap directly to the left of them both read crazy high ohms that jump around or keep growing until infinite.

can i desolder these caps and test with my ESR?
i never messed around with these tiny smt caps before

[mmartell]

Re: Element ELCHS321 has 5vsb and red light but wont turn on

Clean that board up, man! Get yourself a toothbrush (preferably your wife's or girlfriends ) and some isopropyl alcohol and start scrubbing. Don't worry about the smd stuff yet.

It looks from here like the leg of that mosfet is burnt but can't tell because of the condition of the board.

And I thought my set was similar due to the model numbering but it's possible it's not anywhere near the same. Post a pic of the entire back of the set.

[triplefour]

Re: Element ELCHS321 has 5vsb and red light but wont turn on

wifes toothbrush...haha! no wonder tech's are single

ok i cleaned it all up with the propyl

and took another picture of the back, and the model numbers on my PSU...
RSAG7.820.1411/R0H VER.D
what next?

typing "schematic" at the end of that in google didnt get me anywhere :/

[mmartell]

Re: Element ELCHS321 has 5vsb and red light but wont turn on

Some of those traces look suspect. Make sure there is continuity along them.

My board was different btw.

[triplefour]

Re: Element ELCHS321 has 5vsb and red light but wont turn on

yeah i checked, the traces seem fine... its the cap and resistor on the right im worried about..and i dont even know what that other thing is...

edit: resistance on that cap and resistor on the right have gotten better with the cleaning. they seem close to what im getting on the other caps...my digital meter's battery ran out though so im only using the analog meter and im not really sure how to read the ohms. i just know the needle is going to around the same place....

[triplefour]

Re: Element ELCHS321 has 5vsb and red light but wont turn on

well i let it rest that night and the next night, i didn't even mess with it i was just going to put it all back together and put it on the side till i figured out something else...but after i had it back together i decided to try power it on and boom! it totally works now!
i guess all it needed was the dead gecko cleaned off real good!

dang another TV fixed but no lesson to learn.
oh well! now i can sell this TV and get a Hot Air station.

[Agent24]

Re: Element ELCHS321 has 5vsb and red light but wont turn on

The lesson is probably that conductive and corrosive lizard residue stuck on a circuit board can cause improper operation and PCB damage.

[triplefour]

Re: Element ELCHS321 has 5vsb and red light but wont turn on

true but i meant like learning how the power supply actually works...still pretty foggy on a lot of things

[Agent24]

Re: Element ELCHS321 has 5vsb and red light but wont turn on

If you haven't already, learn the basics of SMPS operation - that covers a lot of things. There are many designs but they all come back to the same basic ideas.

Once you know the different sections, you can identify these sub-circuits on a board, and get an idea of what each bunch of parts are for, even if you don't know exactly how a specific implementation may work.

Reading the datasheets and appnotes for the PWM controllers can help.

[triplefour]

Re: Element ELCHS321 has 5vsb and red light but wont turn on

good advice. i know i am just starting out and i have a lot to learn. just gotta invest the time. i got some more TV's to work on today so hopefully one of them will teach me something about the PSU. on a mission to save every TV i can from the landfill!