Ex-Link Cable for C/D/E Series and BD players
On most C-Series the Ex-Link port is located at the VGA connector of the TV.
This page explains how to access the serial console on C-Series TVs with no 3.5mm Ex-Link jack.
If you don't feel capable of soldering such a cable, you can find and buy a cheap (under $5) USB to TTL adapter at eBay.
Prerequisite: Set the RS232 Jack to "Debug" in the Service_Menu.
Step 2: Cabling
As the TV has TTL level serial output (3.3V) a TTL-level to RS232-level adaptor is needed, normal RS232 Level is up to 15V which can cause seriously damage at your TV! MAX232 is such an adaptor.
- Pin 4 at the VGA connector is RX (from the TV's point of view)
- Pin 11 at the VGA connector is TX (from the TV's point of view)
- Pin 5,6,7,8 and the case at the VGA connector are GND
MAX232 adaptor circuit V1
Here is a simple circuit using a MAX232 chip to convert the signal from TTL to RS232 level. The Pinout of the connectors is shown at the circuit:
And a picture of the completely assembled board:
MAX232 adaptor circuit V2
See here 
As written before, do never connect your TV directly to the serial port of your PC, as the TV has TTL-level (3.3V) and the PC has normal RS232-level your TV could seriously get damaged by dircet connection!
Connection chain over USB
Recent PCs do not have a RS232 port anymore, but there are USB adaptors available. Most of them use a PL2303 chip for converting the RS232 signal to USB.
This could look like:
Step 3: Start the terminal
On a Linux PC, install 'cu' (call up) tool from the uucp package and run
cu -l /dev/ttyUSB0 -s 115200
On a Windows PC, use Hyper Terminal or Putty.
Settings are: Speed 115200, 8N1, no flow control.
Step 4: Turn on TV
Step 5: Read output
Output should be human readable, like in the following listing. If you get nothing, then your cabling/settings are incorrect. If you get garbage, then you have problems with the MAX232 circuit.
================================================================================ SAMSUNG: v2.6.24_SELP_4.3.x_GA(P20) (Detailed Information: /sys/selp/vd/lspinfo/summary) ================================================================================ 2.0 : 0 : 256 init started: SELP-BusyBox v1.6.0-VD Linux SELP.4.2.1.x (2010-01-21 19:31:50 KST ) multi-call binary starting pid 29, tty '/dev/ttyS1': '/etc/rcS' /etc/rcS start!!!! ===================================================== ROOTFS VERSION : 65-1G-65 ===================================================== it's not dev! starting pid 43, tty '/dev/ttyS1': '/bin/sh' -sh: id: not found 1st partition!! /dtv/PART_FLAG_0 is detected... 1st Partition is selected....
Step 6: Enabling serial input
- Turn on your TV set, if everything is connected like described at the steps before the serial log should be shown at the serial terminal.
- Enter 10041004 (when typing the digits No Imput is shown at the serial terminal) and confirm with Enter.
after that you should see:
[SERIAL INPUT MANAGE] serial input ENABLE!!!!!
- So far there is no info on how to enable the Debug Menue at the serial console from the C-Series. The only thing which can be done/executed so far is switching the channels from the serial input.
- Just type a digit like 2 and confirm with Enter. The TV should switch to channel #2.