So I recently received an LG 37LC7D UK from a friend. The TV does not power on and the only sign of life was the standby light that was flashing red and green on repeat. To say the least I was eager to rip into it and upon doing so I found 4 visually bad caps on the power supply board. Ordered the 4 new caps and installed them. Moment of truth and success TV now powers on and has a beautiful picture but has one problem no sound what so ever. I made sure the volume was up and it wasnt muted. I also went into the menu and made sure that the speakers were on. That all checked out fine. I did some research and found the way to get it into service mode to check those options and they all checked out just fine. There is no reset option on this tv apparently so that went out the window. Oh and I find it odd that it is stuck in mono mode for audio selection. I have tried plugging in a chromecast and dvd player and both give me a picture but no sound. There is also no headphone output on this tv so I cant test that option. I have searched google high and low for answers and im coming up empty handed. I have tried to go through the hundreds of posts on this forum but cant find anything similar. Im not very good with forums so I may have missed it and if I did i apologize. I did find a random youtube video with a tv with a similar problem and it said it was a bad resistor on the main board. I have a multi meter and I am still learning how to use it to its full potential. There is a cluster of resistors prior to the 4 pin output to the speakers and I believe I tested them right but I could be wrong. There were a couple smd resistors that had a funny reading but then again I could be testing them wrong hence why I am here...to learn. One would think it would be the main board but there is still a part of me that questions the power supply board.So if anyone has some insight on this it would be much appreciated. All I ask is to please be patient with me, I know enough to get me in trouble but not enough to know what I am doing. I am still learning and appreciate all the help I can get. All the TV's I have fixed have just been replacing the entire board but I want to take it to the next level and attempt to fix the board. Makes the puzzle more interesting. Thank you in advance and if there is any other info needed just ask and I will do my best. Can you tell this is my first post in a forum?
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Last edited by bleed4me; 11-03-2015, 10:47 PM. -
Re: LG 37LC7D UK has image has no audio
Can you take some pictures of the boards and how they are laid out please ?Please Do Not PM My Page Asking For Help Badcaps Is The Place For Advise, Page Linked For Business Reasons Only. Anyone Doing So Will Be Banned Instantly !
https://www.facebook.com/Telford-Tel...7894576335359/ -
Re: LG 37LC7D UK has image has no audio
See if you get any power to the audio IC? Check a different input maybe something RF or RCA... Not that there is something wrong with the HDMI.Comment
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Re: LG 37LC7D UK has image has no audio
Check 3.4V on power supply. Common fault with these is low 3.4V causing no audio.Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
For service manual, schematic, boardview (board view), datasheet, cad - use our search.Comment
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Re: LG 37LC7D UK has image has no audio
Thank you for the responses. Give me 8 hours and as soon as I get off of work I will upload pictures and do some testing and report back with my findings.Comment
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Re: LG 37LC7D UK has image has no audio
Maybe also worth doing a full capacitor recap of this power supply as you have only replaced four it dose not mean the others are good.Last edited by vinceroger69; 11-04-2015, 12:10 PM.Comment
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Re: LG 37LC7D UK has image has no audio
A full recap is definitely an option...for the sake of curiosity is there a solid way of testing them without an esr meter?Comment
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Re: LG 37LC7D UK has image has no audio
no you need a esr meter really but you can find some good capacitor kits online with all the ones you need in it, when you get a moment can you find the power supply number etc, and what brand of capacitors did you use when you changed just the four visable faulty ones.Comment
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Re: LG 37LC7D UK has image has no audio
That sir is a question I can answer without having the TV in front of me...the power supply number is LG AGF35626301 and the 4 visably bad caps I replaced with Rubycons from digikeyComment
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Re: LG 37LC7D UK has image has no audio
that part number is the mainboard?Comment
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Re: LG 37LC7D UK has image has no audio
Sorry about that you are absolutely right...had the wrong picture...EAY3866901 is the PS.Comment
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Re: LG 37LC7D UK has image has no audio
can you double check that number as it does not come up with anythingComment
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Re: LG 37LC7D UK has image has no audio
Apparently I need to brush up on my multitasking skills...lol...try EAY38669901...Comment
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Re: LG 37LC7D UK has image has no audio
yes thats the correct one when you get time check all the voltages as tom suggests and we can go from thereComment
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Re: LG 37LC7D UK has image has no audio
CapLeaker I tried every input on the board and they all show the same result perfect image and no sound. As far as the audio ic I honestly dont know what that is or where to even find it. If you could possibly explain it more that would be appreciated otherwise I will get my google on and do my best to test it for you. I do apologize for the pictures they are not the best, if it would make things easier I could use a stock photo online and post them. The picture of the power supply I put red dots on the caps I replaced. I did use stock photos on the connectors so you had a better idea of what i am testing. I will say this #2 photo confuses me as to the writing on the board but I will do my best. Here are the values
#1
3.4on-2.56
GND-0
6.5-6.75
A DIM-.02
GND-0
ST 5V BURST-5.45
DIM-.17
ERR INV-.87
CTRL-3.34
GND-0
ST5V-5.44
ON/OFF-3.12
ACD-5.32
#2
GND-0
12V-13.52
GND-0
3.4V-3.74
GND-0
6.5V-6.71
now the remaining 4 pins I dont understand the board but here are the values
0
0
.47
.47
I hope all this helps and please if i can do something better or am doing something wrong please correct me . I am here to learn. Again thanks for the helpAttached FilesLast edited by bleed4me; 11-04-2015, 07:17 PM.Comment
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Re: LG 37LC7D UK has image has no audio
i think the first connector 3.4 on is just a on signal so the slightly lower voltage maybe ok maybe tom66 or budm will advise if they can on connector two the 3.4 volt is ok by the looks of it so im not sure what else to advise except maybe fully recap the rest of the board and see if the sound comes back.Im still new to electronics so not sure what else to advise sorry.Comment
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Re: LG 37LC7D UK has image has no audio
No need to apologize any insight is welcomed and appreciated. I myself still learning this so you are not alone.Comment
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Re: LG 37LC7D UK has image has no audio
Double check the 3.4V, should be around 3.3-3.5V, the 3.74V looks too high.
My faulty set, with same symptoms, had 3.4V at about 2.5V. TV still had picture, but sound was intermittent and Freeview tuner sometimes failed to work.Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
For service manual, schematic, boardview (board view), datasheet, cad - use our search.Comment
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Re: LG 37LC7D UK has image has no audio
Will definitely recheck those as soon as I get home. Should I be concerned with the low reading on the 3.4v in on connector 1 or the high 12v pin on connector 2?Comment
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Re: LG 37LC7D UK has image has no audio
tom66 this is the thread i saw post 20 where you said 2 volt is ok as its a on signal
https://www.badcaps.net/forum/showth...ight=LG+37LC7DComment
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