crt tv china Board voltage sinhala video with english - ටීවී බෝර්ඩ් වල A to Z වෝල්ටේජ් හදුනාගනිමු

About the one horizontal line problem in TV, you can also suspect the switch mode power supply because if there is no supply to the vertical section, obviously the vertical section would not work thus producing a straight horizontal line across the screen.

Now assuming you have identified the vertical section, you need to perform the voltage test on the Vertical IC, what is the next step you should do? Simple, get the schematic of the vertical IC and find out the supply voltage (VCC) pin. Once you have identified the pin now turn On the power and place your red probe to the VCC pin and black probe to cold ground. Read the voltage and if it is good then perform the waveform test which I don’t cover in this article. If the voltage is low or missing then you got a clue that either the supply line has problem or the vertical IC itself or corresponding components have problem that pulling down the voltage.

Here is the way on how you can perform the voltage test along the supply line. Move the red probe backward till you meet a resistor (usually this is a low ohm resistor or a protection resistor- 0.22 to 1 ohm). If you still do not get the right voltage then I suggest that you lift up the resistor and recheck the voltage again or you can directly test the ohm value of the resistor.

Note: A bad filter cap (high ESR value) along the supply line to the vertical IC could cause the voltage to become low.
The above test is about tracing voltage backward and what if you need to trace it forward? Same principle, understand the circuit function and place the red probe onto the right place. SMPS produce DC output voltages and you can follow the line till you reach the last point of the circuit. For example, tracing the B+ voltage line till flyback transformer pin and you may pass through a resistor and that resistor is usually a low ohm resistor (0.22 to 1 ohm). Since this is a low ohm resistor you can expect the voltage to be same or slightly drop a bit after the resistor. If you get zero output voltage then you will automatically know that the resistor had an open circuit.
For your information not all circuit are created the same. For example, the Monitor B+ circuit that have boost and buck circuit. If you trace from the DC output to the Boost circuit then you have to expect an increase in DC voltage at the output of the circuit. If you are tracing the Buck circuit then expect a lower voltage at the output of the circuit. Isn’t it important to understand how a circuit work (I mean CRT Monitor circuit) if you are in the CRT Monitor repair?

Now, not all DC voltages that passes through a resistor will drop in voltage, some resistors are directly connected to ground like the bleeder resistor. If you follow the DC output line and trace after the resistor you will get ZERO volt.

Conclusion- Understand how electronic equipment work and be able to identify each of the section of the equipment will give you a great advantage of solving a problem fast by using the simple voltage test method. What you need to do is to practice more on a working board (with power On) and write down all the critical test points of that equipment so that in the future if any of those equipment come in for repair you will roughly have an idea on what are the voltages to expect on those section (test points) even without have to refer to any schematic diagrams. Have fun in repairing and all the best to you!

Видео crt tv china Board voltage sinhala video with english - ටීවී බෝර්ඩ් වල A to Z වෝල්ටේජ් හදුනාගනිමු канала Ama Tech99