Samsung 153V LCD Monitor Netzteil Reparatur-Tipps

Fehlerbehebung Samsung LCD 153V Netzteil ist wie Fehlerbehebung die CRT-Typ. Dieser Monitor kam mit keinen Strom Symptom. Wenn Sie zum ersten Mal die Reparatur dieser Art der Stromversorgung sind, empfehle ich Ihnen, zuerst die Schaltnetzteil Trafo. Dann testen Sie jede einzelne Komponente im primären Bereich, bevor Sie an den sekundären Abschnitt überprüfen fortsetzen. Sie haben gut zu sein in Tests grundlegenden elektronischen Komponenten, um die Fehler zu erkennen.

Sie könnenalways browse through my website just in case you do not know how to test basic electronic components. If you do not know the right way to check, you might miss out a bad component and this will lead you not able to solve the problem. After carefully checking all the components in the power supply section, I found the filter capacitor do not have any reading using digital capacitance meter (open) , the two round type fuse also open circuit, 1N4744 15 Volt zener diode short circuit and lastly the power ic TOP247F blown! Testing the switch mode power supply primary winding with a dick smith flyback tester shown green bar which indicated good winding.

What we left here were the secondary diode and filter capacitor. Upon checking them with analog meter and esr meter, found all of them to be good condition. Other area like main board and inverter board also looks okay (Power failure rarely affect these two circuit). Now we have confirmed that only five components found to be faulty. One by one the components were replaced (except one fuse) and just before you switch on the power supply, make sure you connect a 100 watt light bulb across the live ac line-refer to the photo at my website. Once it is done you can then proceed to switch on the LCD monitor to look at the brightness of the bulb.

Samsung 153V LCD Monitor Netzteil Reparatur-Tipps

If it very bright, this suggests that there are still short circuit somewhere in the power section. If it dim or totally goes off, you can now place your red probe to the secondary side to check if any dc present at their respective line. If there are DC voltages present at the output, you can switch off the power, discharge the filter capacitor (for safety purposes), remove the light bulb and connect back the new fuse to its original location.

You are now hundred percent sure that the LCD power supply won't blow once you switch it on. By the way the filter capacitor is rated at 105 Celsius and you cannot replace it with the 85 Celsius type otherwise it may open up again after using for couple of weeks or months. The ventilation in LCD monitor is not as good as the cathode ray tube monitor, because the power supply is fully covered by a large aluminum plate and it can get hot pretty fast. Conclusion, whether you are repairing Samsung 153V LCD power supply or other brand of LCD monitor, the procedure is the same. Who knows the power problem in this monitor is a common fault and in the future you can tackle this brand of power supply in the shortest time. To measure electronic components is not that difficult, but to get the original parts like the power ic will consume you lots of time.

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Repairing Samsung 153V LCD Monitor With Dim Display Problem

One of the common problems in Samsung 153v LCD Monitor was display dim. If you get closer to the screen and begin to observe the display under dark environment you actually could see the display but it was very dim. If you press the front panel button, the on screen display (OSD) would appeared and this proof that the main board, driver board and LCD panel is working and the problem is in the inverter board. The function of inverter board is to generate an ac wave from dc voltage to power up the lamps which was located at the top and bottom of the LCD Monitor. If the inverter board has problems it would not light up the lamps and what you could see only a dim display.

I still could recall when I first encountered such problems long time ago and because of lack of information, I could not solve it. I did call up my repair friends to asked about the solution but no one able to give me an answer. Even if you surf the internet for "Samsung 153V LCD Monitor dim display repair", you would not find it. Due to this I have to do my own research to find the answer and I've never give up. Winston Churchill once said "Never, never, never give up". I'm releasing the solution only to my loyal members or subscribers only-thanks for your support.

Let's start now! Once the cover and the internal aluminum casing were opened I saw two bulged filter capacitors at the secondary side of switch mode power supply. The value was 470 and 1000 microfarad 25 volts. I saw four more electrolytic capacitors located at the inverter board have changed color and the value was 47 micro farad 25 volts. Browsing through the whole board with my ESR meter I found another capacitor faulty (220 uf 25 volts) which was near the fuse (3amp). Since this capacitor was located at the same line with the fuse, I presumed that the fuse may give way as well. True enough, checking the fuse with an ohmmeter revealed that it has open circuit.

Repairing Samsung 153V LCD Monitor With Dim Display Problem

Now, the real problem faced by many electronic repairers who deals with this model was, after replacing all of the components above the LCD Monitor still would not work-it's still dim! First you have to ask yourself why the fuse blown? Could it be caused by the defective capacitors or something shorted beyond the fuse line? The nearest circuit to the fuse was the start circuit that consisted of a pair of NPN and PNP digital transistor (4k7 +4k7 resistor built into the transistor). Some other LCD monitor designed used the combination of C945 and A733 in start circuit. By the way the part number for Samsung 153V start circuit transistors were the A6J (PNP digital transistor) and the A8J (NPN digital transistor) as shown in the picture.

Sometimes only these transistors have problems (shorted) that caused the fuse to blow but in the above case both digital transistors are tested okay. Since both transistors were working, now the concentration have to be in the four ic's that drive the high voltage transformers because the 12 volts voltage was supplying to each of these ic's. These 4 ic's have many part numbers and the most common one that the manufacturer used was 4532m. Some board used the AD4E10 and BBD3N13 part number. At the moment it is quite hard to get the datasheet or technical specification for this number even from the web search.

Do you know what is inside these IC's? It is actually a pair of P-channel and a N-channel mosfet built into it. And do you know that it can be test with a meter? Yes, if you use the Peak atlas component analyzer, it would prompt to you the result. From the result what you get are N channel FET located at pin 1 (source), pin 2 (gate), pin 7 & 8 (drain and both pins joint together internally). As for P channel FET, pin 3 (source), pin 4 (gate) and pin 5 & 6 (drain and both pins joint internally). From the above test I found two of these ic's have shorted. Replacing these two shorted IC with the capacitors and fuse put the LCD Monitor back to life!

One more thing I would like to share on this model was that the inverter PWM IC BIT1305 was quite robust and rarely gave problem.

Jestine Yong is a electronic repairer and a writer, for more electronic and LCD MONITOR repair information, please visit his website at http://www.electronicrepairguide.com/lcd-monitor-repair.html

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