In 2007, my brother bought an HD-capable LG 26LC7R TV, and we put away that 20-year-old CRT TV (which actually worked).The new TV has analog and two HDMI inputs, and now, more than 10 years later...I saw 3 swollen 680µF/35V capacitors near the heat sink (pictures 3 and 4) on the switch mode power supply (SMPS) board 24V 3A CCFL inverter power supply.No doubt the heat from the heatsink evaporated the electrolyte, I replaced all the large electrolytic capacitors and the measured output voltage on the SMPS connector was fine, but the first problem still persists.After 45 minutes of operation in HDMI mode, the video turned to a still image, then faded to white and looked hot.Again, the sound is still fine.Immediately shut down for a few minutes to cool down.After unplugging it, I found hot spots on the SMPS secondary heatsink, the motherboard IC, the main processor (hottest), and the HDMI switch IC.To determine if cooling failure was the likely cause, I installed a fan to cool the motherboard of the TV that was turned on.It has been working before.There are many low dropout regulators (LDOs) and (aging) SMD capacitors on the motherboard, but all voltages are normal.Will the unstable regulator output cause heat?I recall the warning from the EDN article about LDO being unstable.In addition to the existing SMD capacitors, I added a couple of electrolytic capacitors to the output as shown in Figure 5.However, they didn't work, so I removed them again.The main processor (VCT 7993P-A1-H000) may have reached a temperature of 100°C when cooling is stopped (Rth(JC) = 35K/W, assuming 2W power consumption, 208-pin TQFP).Return to work at 67°C.There is a copper core for cooling under the processor, and the PCB designer did not provide a cooling surface (Figure 8).TVs work fine in cold temperatures, but can go wrong in tropical countries because…You must Register or Login to post a comment.