Accessing the service menu of the TV enables you to set hundreds of advanced settings. This page tries to list the interesting options that may worth changing. Be aware though, making changes in the menu may void the warranty (and/or make your TV inoperable), so here's a big WARNING! You can damage your TV with this! Additionally, according to some people the TV is logging the changes made in the service menu.
When the TV is off, hit INFO MENU MUTE POWER keys in this order. The TV turns on and you see a large menu structure. If you do not see the menu, try the same procedure with MUTE, 1, 8, 2, POWER instead. Usage: Up&Down arrows make selections while Right&Left arrows makes changes. You needed to backup previous value before changing any option. Some options cannot be reverted once changed. The service menu has a protected 'advanced' submenu. Press the 0 button four times on advanced to enter the hidden menu. Before touching any setting, please note the original value. The menu settings are listed (with their default values?) in the Service Manuals.
Enable serial console
Change setting for your RS232C interface to "debug" ( Control -> Sub Option -> RS-232 Jack -> [ Debug | UART | Logic ] ). More info is available on the Enable_Serial_Console_on_non_CI+_Devices page.
Configure sound delays
To eliminate the echo between the TV speakers and the external amp speakers, choose Control->SOUND, Change Auxout Delay Normal to the same value as Speaker Delay Normal (100). This can also be changed (in real time) to to find the perfect audio/video sync.
Enabling Add/Delete in Content Manager
If your TV does not have the functions to be able to add or delete content to the TV memory using the Content Manager, this can be enabled: Control -> Sub Option -> Wiselink Write -> On
You should not have to read this. Having to read this means that you have not respected the warnings and messed up your Service Menu. Anyhow, now it's too late, so we try to help. But there is no warranty, and you can read on the net of people bricking their TVs by selecting bad panel types.
Restoring Panel "Type"
Inch Vendor (A:AMLCD, D:CMO, L:AUO, I:CPT) Panel frequence (6:50/60Hz, 1:100/120Hz, 2:200/240Hz) Panel (A: Anti Glare, T: Twisted Nematic U: Ultra Clear) Resolution (F: Full HD, H: HD (ready), U: Ultra High Definition TV) Panel 1st/2nd (1st:0, 2nd:1...) BLU (C:CCFL, L:LED, E:Edge LED)
32D1UF0E : Vendor: CMO inch: 32 120Hz FHD U/C Edge LED panel 40A2UF1C : Vendor: AMLCD inch: 40 240Hz U/C panel CCFL