Tuesday, February 17, 2015

HOW TO ENTER SERVICE MODE SAMSUNG - CS21S8NAS/MUR CRT TV AND POWER SUPPLY CIRCUIT

SAMSUNG - CS21S8NAS/MUR 

CRT TV

SERVICE MODE AND POWER SUPPLY CIRCUIT

Service Mode
To enter the “Service Mode”, Press the remote-control keys in this sequence :
- If you do not have Factory remote-control
PICTURE OFF --> DISPLAY –>  MENU --->   MUTE  -->   PICTURE ON
- If you have Factory remote-control
PICTURE ON ---> DISPLAY --->  FACTORY
Use the Channel Up/Down buttons to move the cursor in the adjustment parameters.
- When CRT, CRT PCB, FBT, E2PROM (sometimes MICOM) is replaced, the adjustment values should be controlled.
- After the Service adjustment is completed, Do not select “Reset” in the service mode menu. (After above procedure is done, power is on initially and the “Plug and Play” will be operated.)
Alignment and Adjustments
General Alignment Instructions
1. Usually, a color TV-VCR needs only slight touch-up adjustment upon installation. Check the basic characteristics such as height, horizontal and vertical sync and focus.
2. Observe the picture for good black and white details. There should be objectionable color shading; if color shading is present, demagnetize, perform purity and convergence adjustments described below.
3. Use the specified test equipment or its equivalent.
4. Correct impedance matching is essential
5. Avoid overload. Excessive signal from a sweep generator might overload the front-end of the TV. When inserting signal markers, do not allow the marker generator to distort test results.
6. Connect the TV only to an AC power source with voltage and frequency as specified on the backcover nameplate.
7. Do not attempt to connect or disconnect any wires while the TV is turned on. Make sure that the power cord is disconnected before replacing any parts.
8. To protect against shock hazard, use an isolation transformer.
Automatic Degaussing
A degaussing coil is mounted around the picture tube, so that external degaussing after moving the TV should be unnecessary. But the receiver must be properly degaussed upon  installation. The degaussing coil operates for about 1 second after the power is switched ON. If the set is moved or turned in a different direction, the power should be OFF for at least 10 minutes
If the chassis or parts of the cabinet become magnetized, poor color purity will result. If this happens, use an external degaussing coil. Slowly move the degaussing coil around the faceplate of the picture tube and the sides and front of the receiver. Slowly withdraw the coil to a distance of about 6 feet before turning power OFF. If color shading persists, perform the following Color purity and Convergence adjustments.
High Voltage Check
CAUTION : There is no high voltage adjustment on this chassis. The B+ power supply should be +135 volts (with full color- bar input and normal picture level).
1. Connect a digital voltmeter to the second anode of the picture tube.
2. Turn on the TV. Set the Brightness and Contrast controls to minimum (zero beam current).
3. Adjust the Brightness and contrast controls to both extremes. Ensure that the high voltage does not exceed 30 KV under any conditions.
FOCUS Adjustment
1. Input a black and white signal.
2. Adjust the tuning control for the clearest picture.
3. Adjust the FOCUS control for well defined scanning lines in the center area of the screen.
SCREEN Adjustment
1. Input Toshiba Pattern
2. Enter “Service Mode
3. Select “G2-Adjust”.
POWER SUPPLY CIRCUIT 
CLICK ON THE IMAGE TO ZOOM IN