LG 37LC2D No Sound, and No Channels

[whitemus]

Re: LG 37LC2D No Sound, and No Channels

The 12v drops to 11.0 when the middle is unplugged.

[whitemus]

Re: LG 37LC2D No Sound, and No Channels

sorry, I double posted.

[tom66]

Re: LG 37LC2D No Sound, and No Channels

So it's almost dropping the same as the 6V does, which leads me to believe there's a short circuit on the board between the 12V and 6V. I have no idea if this could cause your issue - but it's definitely a problem. The higher voltage could potentially cause a voltage regulator (or a few) to overheat, causing some odd problems.

Did the problem suddenly develop or slowly get worse?

Can you unplug the TV, wait 30 seconds, then remove the power board and take a clear photo of the under side (green side?) From memory there are MOSFETs providing 6V, which could short-circuit.

[whitemus]

Re: LG 37LC2D No Sound, and No Channels

Okay, well there is definitely a blow out! This must have been the problem the whole time.

[whitemus]

Re: LG 37LC2D No Sound, and No Channels

There is also a rattle noise coming from the board when I shake it. Sounds like something is loose inside of something else.

[tom66]

Re: LG 37LC2D No Sound, and No Channels

Yeah, these TVs have always amazed me - the power board can have a severe failure and the TV still mostly works. That right there is a MOSFET which has had a bad day.

The damage is likely to extend further than that MOSFET, so I would say getting a new PSU would be the best option, unless you want to repair 20 other SMD components.

I think the rattling is the relay, it is normal. When you plug in or turn on your TV you probably hear a click or two, the relay is making that sound. It consists of a contact, which can move, and a coil, which pulls the contact when the coil is energized (current flows through the coil.)

I just hope that no damage has been done to the main boards.

[whitemus]

Re: LG 37LC2D No Sound, and No Channels

I will try a new PSU and see what happens. Hopefully the rest will be fine. I'm really unsure about the TV not getting channels though. Makes me believe that something else may have blown too. I really appreciate your help! I'll report back and let you know the outcome.

[tom66]

Re: LG 37LC2D No Sound, and No Channels

I will try a new PSU and see what happens. Hopefully the rest will be fine. I'm really unsure about the TV not getting channels though. Makes me believe that something else may have blown too. I really appreciate your help! I'll report back and let you know the outcome.

Visibly check the main boards for signs of burning or damage.

Then unplug all of the power connectors and test the resistance between the 6V and case of the TV... I'd guess you should see more than 1k ohm.

[multimeter]

Re: LG 37LC2D No Sound, and No Channels

Visibly check the main boards for signs of burning or damage.

Then unplug all of the power connectors and test the resistance between the 6V and case of the TV... I'd guess you should see more than 1k ohm.

"I'd guess you should see more than 1k ohm" spot on,i repaired a uk version with bad 6v and a 12v rail the resistance to ground on the rails was 1027kohm,unfortunatley the psu had simular damage from shorted mosfet on solder side,loads of smd fried and open circuit,it was more economical to replace the psu,(bout £25 i think),the tv worked fine after that.

[ergela]

Re: LG 37LC2D No Sound, and No Channels

Hello, I have a similar problem, no sound.
Just voltage on 3.4V is incorrect
3.4V-1.16V
Middle connector unplugged 1.16V
I had 1 bad capacitor, after replacement most of them except 3800uF ( green V mark) beside connectors, no difference
When the TV is off few hours sometime the sound is back and the led beside 'x' is lighting. After a few minutes the sound is cracking and getting off then I see this LED gets dark and off
Any help is much appreciated !

[tom66]

Re: LG 37LC2D No Sound, and No Channels

My personal theory is the buck converter IC is failing (8pin SMD on bottom of PSU board) but I've never been able to confirm such.

[ergela]

Re: LG 37LC2D No Sound, and No Channels

Thank you Tom66, i just look at the forum on your Thread https://www.badcaps.net/forum/showthread.php?t=20932 a got the exact same problem and same caps.
It is 100% PSU? I think i have no chance to fix this one, can't find this 8pin SMD on the internet and we are not sure 100% is it this one, probably i need to buy a new PSU .

Do you mean one of those 8pin SMD?

[tom66]

Re: LG 37LC2D No Sound, and No Channels

Yes, the one without the large copper areas connected to it, it is the controller chip.

[ergela]

Re: LG 37LC2D No Sound, and No Channels

3037CS
611P
CC1M7

On which number i should look to find one?
I found one, it is same or different? I looked at no. 3037cs

"8-PIN SYNCHRONOUS PWM CONTROLLER" http://www.datasheet-photos.com/ProI...tNumber=3037CS or here: http://www.aliexpress.com/wholesale?...20130813071852

[tom66]

Re: LG 37LC2D No Sound, and No Channels

http://www.ebay.co.uk/sch/i.html?_tr...at=0&_from=R40

[ergela]

Re: LG 37LC2D No Sound, and No Channels

tom66 thank you for your time. So just the no. 3037sc is important? no matter which i will get just must be 3037sc because is see they have different numbers below

[tom66]

Re: LG 37LC2D No Sound, and No Channels

The other numbers are production/lot codes, so not usually important.

[tom66]

Re: LG 37LC2D No Sound, and No Channels

One thing to make sure is that you get the SO-8 or SOP-8 size which matches your board (compare the ratios), not the MSOP, or other sizes.

[ergela]

Re: LG 37LC2D No Sound, and No Channels

Ok I will let you know how it works when I replace. Thank you!

[ergela]

Re: LG 37LC2D No Sound, and No Channels

I replaced 3037sc but no result
After this I swapped this 2 smd beside 3037sc [ 2 are the same] they going there where was a bad capacitor and now 4th red led is on but I think not bright enough.
You think it could be the problem?

Look at the picture, I should look for ic smd IRF7807Z or other numers? http://www.ebay.ie/itm/IRF7807Z-INTE...item2ec7bba515