Hidden Secret Service Codes for Sony and LG TV

NOTE: Please note down the default values before changing them, so that you can restore them if something goes wrong or you don't like the output.

All digital TVs contain a secret service code which allows you to change some internal settings like picture height, width, position, colors, etc. Basically this service menu is used by TV mechanics.
Here we are sharing service codes for LG and Sony TVs.

For Sony TV:

First power off your TV using remote, then Press <Display> + 5 + Vol Up + Power button simultaneously on remote.
Now you can make desired changes to the settings.
To save the changes, just press Mute + 0.

For LG TV:

Press and Hold <OK> button on remote as well as TV panel at the same time for a few minutes.
Now you can make desired changes to the settings.
To save the changes press <OK> in Remote.

PS: Be very careful while playing with the service menu. First make changes but don't apply them. If something goes wrong, just switch off the TV and switch on it again.