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LG Home Theater As No Audio

By Jestine Yong on August 17, 2024

A new customer came to my workshop with this home theater with complaint of playing but no sound. So i did the usual and probe through the device, nothing to suspect. So i thought perhaps the problem may be with audio ic which are placed under a big heat zinc. I desolder heat zinc and there are three audio ics. It was not possible for me to determine there condition, so i just scrap out the dry thermal paste and apply fresh on it and re- assemble the device, power it On…no sound still. Since i do not have much skill on how to repair this type of device, i decided to seek help.

So i pass it over to another technician who have knowledge. How he did repair it i don’t know for he didn’t let me see, he just handed it over to me after a period of time and there it is with sound, and i didn’t ask him how he repaired it, for i knew he will not tell me….no experience sharing within mine people….they always see every other technicians as competitors…..what an archaic way to think.

However i took the device to workshop and disassemble it again to scrutinize it as to see what he did….alas i saw it. Let me drink water before i reveal it……now i am ok with cooling water.

how to repair and fix a broken home theatre LG

From 3rd picture, if you zoom, you will see the areas that is blue circle some e-capacitors and a smaller blue circle with an smd tiny capacitor, there are about eleven of them lined up to the right side, now on the 2nd picture, if you zoom, you will notice the tiny smd cap has been broken off without replacement ….so what the technician did was to break all the smd caps on that line, and sound came up…..and that’s what he didn’t want me to learn.

Now the question is why did he break those caps and it solved the problem ? Your guess is as good as mine!!

So i called the customer to collect his device. This is the finished repaired work.

This article was prepared for you by Imoudu Onwumah from Nigeria. He is 62 years old and has just 3 years experience in electronics repairs. I started career in hotel industry as a chef, but then I was doing repairs only in electrical repairs as a hobbyist. In 2018, I decided to learn about electronics which through Jestine’s electronics e-books and holding my hand, am an electronics techie today.

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Note: You can read his previous article on Dead Philip Dvd Player Repaired

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Home Theater System Repair

18 Comments

Parasuraman S

August 17, 2024 at 11:05 am

It would have been ideal if those SMD caps were replaced with their original value. Anyhow, that was beyond your control. I suggest that you check these caps on the board with your Analogue multimeter (x1 & x10 ohms range), as advised by Jestine Yong in his repair books. It should not show any low reading. If so, just pull this up and replace. Normally SMD caps may not have values written on them like resistors. So, we have to study the application circuit of the IC and do it accordingly. Or try to look for service manual of the set, most of which is freely available for download. All the best!

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Albert van Bemmelen

August 17, 2024 at 2:45 pm

Most likely one or more of those smd capacitors shorted the audio signal to ground or they were simply not conducting the signal going through. Something you can easily check and track with an audio signal tracer. By just inputting a sinus frequency of around 1KHz on the input connector and follow the signal through all parts to find where it stops. That is probably what the other technician did to localize the problem.

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- Hollis LuQuette
  
  August 18, 2024 at 10:55 am
  
  I agree and I was going to type almost the same comment ...... I recently repaired a DENON AVR that had 2 capacitors with bad solder joints ....
  
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Yogesh Panchal

August 17, 2024 at 4:33 pm

Imoudu,
Do not get disappointed if they didn't helped you, always try to check surrounding components on reverse way as per the suspected faulty section.there are lots of information on YouTube.specially check SMD DIODE & SMD CAPACITORS For shorting in any device.

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Imoudu.O

August 18, 2024 at 4:14 am

Mr Parasuraman.S
Thanks sir for your candid suggestions,it's noted.

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Imoudu.O

August 18, 2024 at 4:19 am

Mr Albert Van
Thanks for your useful suggestions, in my country such sophisticated technicians' testing tools are not availabl. We make do with what we have.

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Imoudu.O

August 18, 2024 at 4:35 am

Mr Yogest.P
Thanks for your suggestions,i will move forward against all adds.

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Kaladharan. M. D. Dasan

August 18, 2024 at 8:33 pm

I too have a similar LG home theatre, facing no sound problem. Shown to a technician he said pre amplifier is defective. He retu5the set. Earlier the SMPS had a problem. Power supply was rectified by me . Power supply has become defective with lightening. Is the complete PCB is available in market
If so how much it would cost ??

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Imoudu.O

August 18, 2024 at 9:30 pm

Kaladharan M.D
Yes, if you live in my country you can get the pcb at arena shopping complex in Lagos State.If you don't live in my conutry perhaps you can check with e-bay or alli-express.

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PHILIP

August 18, 2024 at 11:59 pm

Imoudu thanks for the technical lesson. Though you may claim not to have the knowhow of testing certain components, but you dont tell us whether or not this components are getting correct voltage or not. Now about mean and envious technicians, I'm sure thats not new to you. I myself have been through automotive repair, phone repair and radio repair and I have seen it all, envy- filled technicians. But anyway, Imoudu, I like your determimation, I like your fighting spirit even more. Just make every use of learning opportunities; internet articles, videos and books, and grab the chance of learning from even dead machines.And, practice, practice and practice repairs. Imoudu I too have learned from your articles. Hi to you all from Kenya.

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Tito Kanshulu

August 19, 2024 at 2:36 am

Very bad for a technician fellow of yours. Anyway, the good thing is that the repair was done and the customer got his gadget in good condition. We all need experience and the guy hid it from you. Thanks for sharing

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AdamS

August 19, 2024 at 5:25 pm

This was not a repair by your colleague - this is a "bodge"!!

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Imoudu.O

August 20, 2024 at 4:47 am

Philìp,
Thanks for your comments and invaluable suggestions,i appreciate it,hàve a nice day.

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Imoudu.O

August 20, 2024 at 4:49 am

Tito
Thanks colleague,and have a nice day

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Waleed Rishmawi

August 20, 2024 at 5:02 pm

could be a shorted bypass capacitor and that is tested by putting the negative probe to ground and the positive checke both side of the capacitor. one side should have a long beep since it is the ground side and the orther side should give you like a diode reading sound. if both side gave you a long beep, the capacitor is shorted and needed replacement. if it is a bypass one and have other ones on the same line with it technicians usually do not replace it they just take off board. have a blessed day

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Imoudu.O

August 21, 2024 at 4:34 am

Waleed.R
Thanks very much for this vital information,i don't have idea of this.

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Imoudu.O

August 21, 2024 at 4:40 am

....."if it is a bypass one", i don't really understand what you mean by this.

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- Waleed Rishmawi
  
  August 23, 2024 at 6:58 pm
  
  Imoudu: bypass mean you can by pass it and the device will work as long there is another part to do the same job on the same line. have a blessed day
  
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