How to troubleshoot an LCD monitor With external power supply problem
Fixing LCD screen power source pack is simpler as compared to the Cathode ray tube screen power source. This is modest and compressed and generally has just one outcome that is 12 volt and varies from 2 Amps to around 4 Amps. Several models works with 18 and 24 volts likewise. These days many LCD power-supplies are constructed in-to the main PCB board whilst in the past most LCD monitors worked with an external power supply unit.
Screens with separate power pack are simple to analyze, mainly because you can swap another operating power unit to know the cause of the issue. You may even utilize an exterior dc power source to switch on the LCD to verify if the power pack is defective.
If the symptoms of your monitor problem are low power, no power and power blink and you don’t possess an exterior dc power source to isolate the problem, then you may make use of this strategy to segregate the issue. Take a 12V light bulb and link it to the output of the monitor power pack. In case it lights normally, then your power pack is alright. In case it dimly lit or flickers the power pack have issue.
Why you have to utilize this process to check it? It is mainly because should there be parts shorted or leaking in the LCD primary board, it’ll impact the power source efficiency. From practical experience, the majority of the LCD power problems whether inside the power pack or built in to main board were because of the failing of electrolytic capacitors that will have a higher ESR because of heat within the primary and secondary area.
The power areas in several LCD screens are yet employing the pulse width modulation IC UC3842 or PWM IC. This kind of IC is very easy to find on the market in contrast to many power ICs that is challenging to obtain. Some Samsung LCD monitors are utilizing the TOP247F power IC that is quite simple to diagnose in case power breaks down within this product.
If you know how an LCD power supply works, then troubleshooting it is not that difficult. In the event you are uncertain of the way to diagnose power source, I encourage you to take a look at the SMPS Power Supply Troubleshooting Guide that explains all the powersupply stages and functions and how to diagnose and repair them.
