A customer brought in a 32-inch LG LCD TV and mentioned that after some port repairs, the TV would no longer power on. It seems like there might be a serious issue with the internal components. I left a message for the customer to call back and provided some additional notes.
After disassembling the unit, I checked the overcurrent fuse and found it intact. However, there was no output from the sub-power supply’s +5V rail. This made me suspect a problem with the power board.
I quickly went to find a board test machine, and sure enough, the issue was indeed with the power board. The sub-power IC used is an ICE3B0365J. Upon inspection, I couldn’t find any obvious damage or breakdown on other components on the board.
Interestingly, the ICE3B0565 chip showed normal voltage output when tested. But the unit wouldn’t power up even after sitting overnight. I tried replacing capacitors C501, C505, and C503, but the cold start issue still persisted.
The only component that seemed to show signs of trouble was ZD502 (24V). When I measured it while it was disconnected, it was clearly leaking. So I decided to replace it. After the replacement, the TV powered on without any issues.
Drop Out Fuse Cutout is a kind of outdoor high voltage protection device, lt is connected with the incoming feeder of thedistribution transformer or distribution lines and primarily used to protect transformers or lines against the impact raised by shortcircuit, overload and switching current. The drop-out fuse cutout is composed of insulator support and a fuse carier, staticcontacts that are fxed on two sides of insulator support and moving contact installed on two ends of fuse carrier, The interior ofthe fuse carrier is the extinguishing tube while the exterior is made of phenolic compound paper tube or epoxy glass.
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Jilin Nengxing Electrical Equipment Co. Ltd. , https://www.nengxingelectric.com