Led flatscreen TV

SOURCE: very poor sound quality

After installing parts on a board some tv's require that you reset some values on the tv's servicing software. This software is only available to certified techs but you can search the net to try and find it. the caps that were replaced should be of exact value in 3 criteria:

1 Voltage
2 micro farads
3 temperature

Also a note of safety:

There are HIGH VOLTAGE circuits inside your tv that could inflict serious harm even when its unplugged if approached wrong. There should be warning stickers all over the chassis of the tv informing you of the danger that your exposed too. When you take out the primary power supply discharge all high voltage capacitors to cancel the harmful charge they are holding. Especially if you just turned the tv off.

Discharging HIGH VOLTAGE capacitors:
use a high wattage resistor of about 5 to 50 ohms/V of the working voltage of the capacitor. If you don't discharge the capacitors or replace caps with inaccurate values you could easily damage other sensitive circuits.

Try resetting the tv back to manufacturers specs and see if this produces better audio quality. And when ever your working on any circuit board be sure that you are well grounded. This will prevent ESD (electro static discharge) which can harm other circuits especially logic circuits. This will cause an imbalance in circuit operation and result in a non working tv eventually.