TCL ace 2175E boot power + B voltage is too high, causing burning tube troubleshooting - News - Global IC Trade Starts Here Free Join
This TV had a strange issue that kept recurring. Initially, the switching power supply didn't vibrate, and the user would occasionally remove the TV casing and it would work fine. This time, the power was cut off, and the TV didn't respond at all. After a few attempts, it still wouldn't start, so the user had no choice but to take it to a repair shop. The shop claimed there was no fault, sent it back, and the user found it still didn’t work at home. That's what the user described. I offered to help through an acquaintance. I thought the problem was likely due to poor soldering. I put aside my current tasks, went to the user's place, opened the case, and carefully checked the power supply solder joints. There were some areas with weak soldering, though not very obvious. Since the user was referred by a friend and only paid 20 yuan for the repair, they were very satisfied and even thanked me, sending me back with the tool.
The next morning, the user called again, saying the TV still wasn’t responding. They mentioned hearing a “beep†from the machine, which was slightly different from before. Based on past experience, this suggested a short circuit. It looked like the problem wasn’t as simple as I thought. I asked the user to bring it in for further inspection. I wanted to save it and use it as a test unit. Once inside the store, I opened the case and found the power transistor was blown. To identify the root cause, I disconnected the load and connected a bulb to test. The bulb lit up, but there was an unusual behavior—when the TV was turned on, the bulb briefly brightened, then dimmed. Using a digital multimeter, I measured the startup voltage and saw that it spiked to around 160V when the switch was pressed, then dropped back to the normal 110V.
The reason for the transistor failure was likely a high starting voltage. I checked the power supply section and replaced the suspected components: the voltage regulator, diode, transistor, and some capacitors. After testing, the voltage stabilized at 110V. To be safe, I let it run for a while. After about 30 minutes, the voltage fluctuated, sometimes reaching 170V before slowly dropping back to 110V. I was confused—why was it still unstable? All the removed parts tested fine with the multimeter. I carefully rechecked the circuit and noticed three small electrolytic capacitors in the power supply. I replaced two of them, but one couldn’t be found. I thought maybe that capacitor was the issue. I found a 35V 100µF capacitor from an old board and replaced the faulty one (C810, 25V 100µF). The TV worked perfectly after that. I ran it for an hour, and everything remained stable. The next day, the voltage was still normal at 110V. Finally, I had solved the problem, like a fish finally finding its way out of the net! Ha ha! (Looking back, I realized that capacitor must have been in good condition at the time, but I just didn’t replace it. Although the process wasn’t smooth, I eventually found the core issue.)
Summary: According to the user’s account, this TV had never been fully powered down. It was only turned off remotely, and the internal circuits continued to draw power. I had warned the user that this wasn’t ideal, as it could cause unnecessary strain on the components. The user was very obedient. If they hadn’t left the TV on continuously, the tube might not have failed this time, since the power supply was working normally. However, the problem was bound to happen eventually. A power supply with aging electrolytic capacitors is prone to failure, and leaving the TV on constantly accelerated the aging process. The first time I fixed it, I didn’t charge much. This time, I wanted to fairly compensate for my effort, so I honestly explained the situation and charged 60 yuan for the repair.
2175E.pdf
ZOOKE provides you with safe and reliable connector products, with 3.96 spacing products providing more possibilities for limited space and creating more value for the research and development and production of terminal products.
3.96 wire to board connectors,3.96 connectors,ZOOKE connectors
Zooke Connectors Co., Ltd. , https://www.zooke.com