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

[triplefour]

got a Element ELCHS321 from the recycler yesterday for 10 bux.

when plugged in i see the red LED and i can see 5vsb on the board
but when i push power, nothing changes.

heres some pics
and the voltages on the connection from the PSU to the Mainboard

pin/name/voltage
1,+5v,0.83v
2,+5v,0.83v
3,gnd,0
4,gnd,0
5,bl-on/off,0.02v
6,dimm,0.83v
7,gnd,0
8,+12v,3.2v
9,+12v,3.2v
10,+5vsb,5.14v
11,+5vsb,5.14v
12,on/off,3.87v
13,gnd,0
14,gnd,0

i dont see any change in on/off or any pin for that matter when i push power button.

[triplefour]

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

i do see a change in the voltage on pin1 of the button board connector when i push power... there are 3 pins on the connector. 1 is ground. the other 2 show voltage drops from 3.3 to varying voltages depending on which button was pressed. the voltage drops from 3.3 to 0. on pin1 when pushing power.
seems the motherboard is getting the signal from these pins to turn on but it is not actually listening....

[triplefour]

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

the connector to the inverter has 14 pins also
the labels are kind of confusing as they dont label each pin individually
but here are the readings i got on the pins
1,4.93v
2,4.93v
3,4.93v
4,4.93v
5,4.93v
6,0v
7,0v
8,0v
9,0v
10,0v
11,0v BRI
12,0.02v SW
13,0.85v PWM
14,0 GND

seems like pin 1-5 are labeled 24v
pins 6-11 are labeled ground
but maybe pin 11 is BRI
because after that there is
only
SW
PWM
GND

[triplefour]

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

heres some pictures of the back of the PSU...
spooky, the main cap still has a charge of 120v after being unplugged for a couple minutes!

i just checked again and it still has like 55v
its been like 10 minutes!

is that a sign of something wrong in the circuit? arent they supposed to discharge a lot faster?

seems like they do on the other sets ive worked on...

[triplefour]

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

well i think i found the problem!
after i looked closer at the board i noticed that a gecko had gotten into the TV at some point and got fried under the PSU board and then fell down into the case.
where he died you can see he rusted some of the case as he decomposed, and on the PCB where he must have initially got fried, theres a row of resistors that are all corroded, probably ruined.

HAH! believe it or not this is not the first time ive seen this.
pretty common in hawaii to have critters crawl up and die in electronics.
i assume they find it when its off and think its a cool place to chill, and then when someone turns on the power, ZZZZZAAAAAPPPP!!!!

can this type of thing be cleaned and fixed up, or do i just need a new board?

[triplefour]

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

jeez...how can i be sure that it didnt fry the motherboard as well?

cause it seems like pressing power on the button board should still generate a change in voltage on the on/off pin for the connector that goes to the PSU, shouldnt it?

[budm]

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

1) So far the main board does send out PS_ON (12,on/off,3.87v) to the power supply board but the power supply is not putting out the 24V as needed by the inverter board.

2) The main board is not sending out the BL_ON (5,bl-on/off,0.02v) (it is labeled as SW (same as BL_ON or Inverter ON) pin on the inverter board).

Try disconnecting the cable from the power supply to the inverter board to see if the 24VDC will show up.

11,0v BRI: Analog dimming control, not used.
12,0.02v SW: BL_ON (same as Inverter ON).
13,0.85v PWM: This inverter uses PWM Dimming control.
14,0 GND

The board looks badly corroded, did you check all the connectors and all the boards for more corrosion? Moisture damaged?

[mmartell]

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

IIRC there are two mosfets under the board, one for the 5v supply the other for the 12v. I had the same set and budm helped me troubleshoot it. In mine I had 5v but no 12v, the 12v mosfet was not opening up completely. I see you have a small voltage on your 5v rail so I would check those mosfets - 8 pin soic I think.

[mmartell]

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

Search ELCHW321 may help.

[Agent24]

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

Clean up all the corroded traces and replace any if destroyed for a start

[triplefour]

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

i dont see anything corroded except where the gecko got fried.
i tried disconnecting the inverter from the PSU and it didnt change anything.
i cleaned up the traces as best i can but no luck... how can i test those components to see which ones are fried? they are tiny SMT capacitors and resistors?
mmartell thank you, i am reading your post.
are you sure that is the same TV though, or just similar?

[triplefour]

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

i do have 2 8 leg IC's on the underside... are these the mosfets you speak of?
what should i test on them?

[triplefour]

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

ugh can someone please tell me what im doing wrong and why i can never seem to find the datasheet for anything?

1207A - nothing
PFLQ - nothing

17A06 - nothing
PBLY
what are the magic google terms?

i read all of mmartell's thread but i still dont really understand what i should be looking for. plus my board is different :/ still a noob

[triplefour]

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

on the 1207A i see 150v on pin1 and 75v on pin 3 but 0 on all other pins.

all pins on 17A06 are zero as well...

and as usual, cant find a service manual...

[selldoor]

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

https://cdn.badcaps-static.com/pdfs/...5fdfffadce.pdf

[triplefour]

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

ok great but HOW did u find those? please teach me how to fish so i dont gotta keep hitting u up for fish!

not that i am in any way ungrateful for these delicious fish.
thank you!

[Agent24]

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

Part of the trick is knowing which number to search for - one is usually just a datecode which won't turn up anything. If in doubt try each one separately.

If you get a match, download the datasheet and verify that the marking in the datasheet is the same as on your actual IC.

[triplefour]

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

hmm now i see it in the results i got but i guess im supposed to know that its a pwm current mode controller... all the extra letters around it threw me off...
NCP1207ADR2

[triplefour]

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

ok from the datasheet i now see that the voltages i was seeing were on the HV pin and the Vcc pin... but why am i getting zero on all the other pins, and on the 17A06?


in mmartell's thread the IC was a mosfet with a S, D and G but mine is totally different... what am i supposed to look for here?

[Agent24]

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

Do you have a scope? You could check for a drive waveform on pin 5. Also check feedback pin to see if it's not causing a shutdown.

If the other IC has no power, find out where it gets power from, it may be it gets switched via something else or the fact it has no power is a clue to the fault