how to fix dead fault TCL L55PSUS
A TCL L55PSUS came to my workshop for repair. The set was completely off and its standby light was not even on.
Fault Analysis
When I turned it on, the set wasn’t responding at all, and its pilot light wasn’t even lighting up.
Fault finding
Power Supply Testing
I opened the back cover of the set and started looking for the fault. First I checked its power supply. The supply was absolutely fine.
Mainboard testing
I checked the voltage of its main board. The voltage on its 5-volt regulator was correct. The voltage on the 3.3-volt regulator was correct. The 1.2-volt regulator was also working properly. Two supplies of 1.0 voltage were connected.
Fault fixed
I replaced the regulator IC UD7 which was providing 1.0 voltage to the system IC for standby. By replacing this part, the standby voltage was met and the system IC started working perfectly and my job is done.
Fault image
I have also marked this fault in the picture and attached it. In it, the fault area and the faulty part are clearly shown so that it is easy to understand the fault.
Conclusion
In modern electronics, especially in LED TV repair, my experience is that fault finding related to system IC requires a very close examination of the voltage of the system IC.
Here, even a slight increase or decrease in voltage can cause a fault, so we should use a good multimeter to measure the voltage.
