LG 37LC55 Flickering and then stand by

[rasketeplas]

Hi, I've a LG 37LC55 my friend give me, it wasn't tuning on and I replaced the caps in power board.
It was working fine, but after a week of use, it started to flickering and go to standby after some minutes. And now it start flickering after 60sec of power on and then go to standby...

The caps seems fine, they only have one week of use, so I don't know what else should I test/look/change...

I've been reading in this forum about C901 replacement in main board, but don't know if is for this kind of problem.

How can I check if the caps I've replaced previously are ok?
Should I change any cap in main board?

Thanks in advance!

[ReeceyBurger123]

Re: LG 37LC55 Flickering and then stand by

Yes failed caps on mainboard, go to my youtube chanel (MrReeceyBurger123) and watch my 32" Lg flickering screen video will help you.

[rasketeplas]

Re: LG 37LC55 Flickering and then stand by

Thanks, I will go and buy some caps and try it.
But the voltage in the IC you show in your video is good, no changes after it goes to standby. So don't know if is the same thing...

[rasketeplas]

Re: LG 37LC55 Flickering and then stand by

I've changed the caps in mainborard, C553, C901, C915, C970, C954 and C975 but is doing the same. After some minutes of working then it goes to standby....

How can I check if the power source is fine? And points to check the voltage and see if it's fine or any component is failing?

[rasketeplas]

Re: LG 37LC55 Flickering and then stand by

one thing is that just before start to flickering and goes to standy, I can hear some 'clicks' in the power source board....what can this be?

[ReeceyBurger123]

Re: LG 37LC55 Flickering and then stand by

Heat the mainboard and see if the fault occurs.

[rasketeplas]

Re: LG 37LC55 Flickering and then stand by

Yes, it seems the fault occurs in seconds after heating the mainboard with a hairdryer....

How can I find the faulty part?

Here is the mainboard with the caps I've changed.

[ReeceyBurger123]

Re: LG 37LC55 Flickering and then stand by

Good image but you have not changed all the caps that I did in the video you need to do that. Also have you an esr meter ?

[rasketeplas]

Re: LG 37LC55 Flickering and then stand by

I did not change the caps near the IC because voltage in the IC was the same as in your video after you install the caps, but I will go and buy more caps


I don't have an ESR meter... what do you thing about this cheap one?
http://www.ebay.es/itm/322041136424?...%3AMEBIDX%3AIT

[rasketeplas]

Re: LG 37LC55 Flickering and then stand by

Now I've changed the same caps as you but still the same... I need to find the bad component..arrrggghhh...

[vinceroger69]

Re: LG 37LC55 Flickering and then stand by

all what you can really do is to narrow down the area your heating i sometimes use a cardboard tube and aim the hot air down it to minimise the area being heated.

or maybe try the opposite try freeze spray see if the set stays on longer as you can freeze small areas

[dick_barton]

Re: LG 37LC55 Flickering and then stand by

Have you checked the voltage on the 3 pin chip right side of board. It looks like a voltage regulator.
What is the part number on the other two other IC's the arrows are pointing to.

[rasketeplas]

Re: LG 37LC55 Flickering and then stand by

The 3 pin chip is a 70SJ61, and the voltage when standby and when tv on is 4.85 , 2.45, 0 (from left to right in the picture)

The other 2 chips where the arrows are pointing: SC156515M

Voltage Standby:
The one at top right:
3.2 3.14 0 1.7 1.13

Top left: 0v in all pins


When TV on, Top left have 3.35 3.35 0 1.3 1.17 (from right to left)


Now i'm trying to heat each single cap with using aluminium foil with a little hole with the cap size let's see if I can find the bad one...

[ReeceyBurger123]

Re: LG 37LC55 Flickering and then stand by

It probably is the issue as the badcaps on the Psu cause excessive stress on the motherboard ones which causes failure, keep us updated

[dick_barton]

Re: LG 37LC55 Flickering and then stand by

The SC156515M are LVD regulators.
Pin 1 Enable
Pin2 Vin
Pin3 Gnd
Pin4 Adj
Pin5 Vout

70SJ61 Cannot find anything on this one.

[rasketeplas]

Re: LG 37LC55 Flickering and then stand by

With the TV unplugged from power cord tonight, this morning I've been heating all main board, and then power on.
The TV then was working fine 5 minutes, and then flickering for some seconds and go to standby....
While flickering , the voltage in the ICs was the same, and after one or two minutes the tv turned on again without doing anything...autopower on . ...and again standby aftert some seconds....

Is there any way to test the power source without the main board?

[vinceroger69]

Re: LG 37LC55 Flickering and then stand by

post good clear pictures of the psu and a coulple showing the connectors and any writing by them we may be able to force the psu on and place a load on the rails and see if theres a issue.
whats the board number on the psu?

[rasketeplas]

Re: LG 37LC55 Flickering and then stand by

Here are the pictures...

I can read here other guy with similar problem solved by replacing all caps near one IC...but I'd like to know the one broken part before doing a massive replace

http://www.abcelectronique.com/forum...ad.php?t=81203

[vinceroger69]

Re: LG 37LC55 Flickering and then stand by

Im not 100% sure what pins you need to link too get the psu voltages up, also what load you need to have on each voltage rail, this may then prove if the psu is faulty or not as without a load the issue maynot show up. im sure budm will let us know what pins too link and what loads to use that way if the psu does go off you know its at fault.

[budm]

Re: LG 37LC55 Flickering and then stand by

Can you please verify the board number? Pink marker in the picture:
http://assets.shopjimmy.com/media/ca...6801-top_2.jpg

http://www.shopjimmy.com/lg-eay34796...wer-supply.htm