TV Samsung KS2A
Popular Samsung TV models with KS2A chassis
Compiled By Imran Ashraf Khan
CS-21A8Q, CS-21A8W7C, CS-21AOWTQ, CS-21A8W7X, CS-21A9WT7C, CS-21A0WT7X, CS-21M6WTQ, CS-21M6WT7X / BWT, CS-21S8NAS, CS-21S8WTQ
CS-2502WTR, CS-25A6NAX, CS -25A6N7X, CS-25A6WTAX, CS-25AGW7C, CS-25D47S, CS-25D47X, CS-25D4BT7X, CS-25D4NT7X, CS-25D4R, CS-25D4S7X, CS29D4R
CS-2502WTR, CS-25A6NAX, CS -25A6N7X, CS-25A6WTAX, CS-25AGW7C, CS-25D47S, CS-25D47X, CS-25D4BT7X, CS-25D4NT7X, CS-25D4R, CS-25D4S7X, CS29D4R
Typical defects KS2A
1. There is no picture or sound.
There is no raster. The LED on the front panel reacts to the on / off control panel. The channels are switched, some hear noise from the speakers.
There is no high voltage. On the board under the terminals of the D5703 line transistor, installed without a heat sink, the darkened area is a consequence of overheating.
There is no high voltage. On the board under the terminals of the D5703 line transistor, installed without a heat sink, the darkened area is a consequence of overheating.
HOT temperature mode in these models is not very well chosen and some transistor instances without additional cooling overheat and fail normally without the formation of thermal breakdown. Probably, the crystal is destroyed.
Replacing the transistor restores the operation of the TV if you install the original D5703 or J6920.
In order not to repeat the developer's error, it is necessary to fasten a small light heat sink to the transistor, for example, the cap from the tuner. The additional area of the cooling surface will improve the temperature regime and prevent overheating.
Replacing the transistor restores the operation of the TV if you install the original D5703 or J6920.
In order not to repeat the developer's error, it is necessary to fasten a small light heat sink to the transistor, for example, the cap from the tuner. The additional area of the cooling surface will improve the temperature regime and prevent overheating.
It should be borne in mind that far from any line transistors can be a worthy replacement for the D5703 (KSD5703), which has a rather high current gain (15-25) and good dynamic characteristics.
Due to the fact that the initial startup from the standby mode is performed with a low driver power supply (8-9V), some transistors may not start SR at all due to insufficient gain of the stream of the line transistor.
For example, with transistors from the BU25 ... series, starting a line scan will not always be stable.
Due to the fact that the initial startup from the standby mode is performed with a low driver power supply (8-9V), some transistors may not start SR at all due to insufficient gain of the stream of the line transistor.
For example, with transistors from the BU25 ... series, starting a line scan will not always be stable.
You can use 2SD2499, the built-in diode does not interfere with the operation of the scan. Its resistor is used instead of standard, then the resistor B-E 22 Ohm on the board must be removed.
We recommend to check the power capacitor driver 220 uF for an overestimated ESR, there were cases that it was he who was responsible for overheating. If it is faulty, due to a lack of current in the base, the key operating mode HOT will be violated, the transistor will warm up to the thermal breakdown temperature, and starting the CP from the standby mode can be unstable.
2. The TV does not turn on
No startup of the power module, overload on the secondary rectifier circuit B +. A string transistor is broken through, or up to tens of Ohms.
The cause of a complete breakdown of the transistor may be FBT failure. FUH29A001 quite often fails.
In this case, the transistor quickly reheats after replacement, there is no high voltage.
Similarly, the thermal breakdown of the transistor can occur as a result of overheating for the reasons already described above.
The cause of a complete breakdown of the transistor may be FBT failure. FUH29A001 quite often fails.
In this case, the transistor quickly reheats after replacement, there is no high voltage.
Similarly, the thermal breakdown of the transistor can occur as a result of overheating for the reasons already described above.
Another reason why the power module in the KS2A chassis may not start is the failure of the capacitor 47 uF 50V in the primary circuit. This is the power filter of the PWM controller.
In this case, sometimes an attempt to start can occur, the LED on the front panel will blink ... but the PSU will not go into stabilization mode.
In this case, sometimes an attempt to start can occur, the LED on the front panel will blink ... but the PSU will not go into stabilization mode.
3. There is no picture. Is there sound.
There is a high voltage. At the accelerating electrode - zero. Internal closure in the picture tube G2 - G1.
The defect is typical for flat picture tubes of 21-29 "and, practically, it is always eliminated without any problems with certain
skills.The short-circuit within a few ohms to several kilo ohms is eliminated by using a 22-100 uF 400V capacitor, charged to a voltage of B + (125-150V ), or from the rectifier VU (180-220 V.) The
closure, measured in tens or hundreds of kilo ohms, is eliminated by the accelerating voltage at its maximum value.
The defect is typical for flat picture tubes of 21-29 "and, practically, it is always eliminated without any problems with certain
skills.The short-circuit within a few ohms to several kilo ohms is eliminated by using a 22-100 uF 400V capacitor, charged to a voltage of B + (125-150V ), or from the rectifier VU (180-220 V.) The
closure, measured in tens or hundreds of kilo ohms, is eliminated by the accelerating voltage at its maximum value.
We will not describe in detail the method of eliminating the closures in a kinescope, because of the possible negative consequences when used by unqualified masters or TV owners.
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