LG 37LC2D No sound, good picture.

[maxvalutech]

This 2006 model picked up at recycling centre is in very good condition for age and very clean when opened. Checked all voltages as aok on power supply and this verified by all green LEDs on both main and input (jack ?) boards. While removing one connector from power board did get a brief squawk from speakers but no sound at all when tested using HDMI and AV inputs from DVD. Had already checked sound turned on in menu. Fitted remote headphone set to AV output and faint sound heard. All this leads me towards amplifier problem. Downloaded a service manual but it doesn't help much as part numbers/description do not line up with what I see. It looks like the input boards going by series (a b c) were changed about three times in one year in this model. Have read a number of threads and sound circuit was a problem with these. I'm not up to replacing other than basic ic items and can get another input board for about $50 (my limit !!). But other of the longer serving contributors to this forum may be able to suggest some tests or components to try first. All thoughts appreciated.

[budm]

Re: LG 37LC2D No sound, good picture.

Do you have Oscilloscope?
IC402: TAS5122
https://cdn.badcaps-static.com/pdfs/...eb7377c9ad.pdf

Does the TV have audio line out?

[maxvalutech]

Re: LG 37LC2D No sound, good picture.

Thanks budm and the TAS5122 is mentioned for replacement in troubleshooting section of service manual. No oscilloscope or such. There is digital audio out which is showing red and av out only.

[Andrew F. Ali]

Re: LG 37LC2D No sound, good picture.

I had a similar problem already. I built audio amps using two LM386 ICs and connected internally to the Audio Out connector and sent the output directly to the internal speakers. Nothing original was overheating so I was lucky. I think the set is still working and this was two years ago.

[maxvalutech]

Re: LG 37LC2D No sound, good picture.

Well I decided to get the input board while available here in Oz. I then put up on local buy/sell Facebook site my ad for broken TVs. Got 5 sets in 3 days and yes one was same lg model as this problem one! The latest one was dead, PSU swollen cap and blown fuse. Swapped PSU and got one working TV. Replaced cap on other PSU but when fitted to set the standby was OK but at switch on led briefly to green then a hiss as fuse blows again so obviously a dead short to search for now on that PSU. Strangely over the few years looking at faults on various sets this is the first time I have had a main fuse blown problem as far as I can recall.