Radio theory handbook

When I was struggling to find out how I can start in electronics in the year 2000.
I kept searching the web for electronics materials and in one site which I cannot remember I found an info which changed my career in electronics completely.

LG CRT Television mode RT-21FB55VE picture top squashed.

I received this television in my shop with the complain of having the top part of the screen squashed and the part of the picture with dark stripes.

I applied the power to confirm what the customer said and this is what is saw.

Understanding the standby circuit in LED-LCD television

When troubleshooting switch mode power supply (LCD/LED TV) it is very important to check the status of the standby voltage.

If you open the LED/LCD television and disconnect both the main board and the inverter board if they are separate, you will notice that only one outlet will have a voltage and the rest will be zero.

This voltage is usually 5Vdc and is called the standby voltage, if this 5 volts standby is not generated means the SMPS is defective and therefore you should not continue with any other test before you know what is blocking this voltage.

Chanwong TV-china with No Power symptoms

This TV has no power symptoms-first I checked the fuse and it was blown but not blacked inside meaning there was no heavy short in the supply.

Remember a fuse can tell you a lot about the last moment of any equipment before it died (in medical terms postmortem)

1. Fuse blown, dark inside - Means the machine died due to heavy short. Please be sure to use the light serious Lamp to bring up the machine after replacing the fuse.

  

2. Fuse blown, clear inside- Means the fuse might have died through natural dead (e.g. old age)