Technical Dispatch

In the operational system of KONE elevators, the LCECPU circuit board plays a core role as the “brain”. It is essentially a miniature industrial computer, responsible for issuing all operational data and commands for the elevator, making it a key component for ensuring stable elevator operation.

1. Characteristics of LCECPU Circuit Board Structure and Operating Voltage

From a structural and functional perspective, the LCECPU circuit board serves as the control core of the elevator, undertaking the important tasks of data processing and command transmission. Its operating voltage is divided into two levels: 24V and 5V. Due to its operation in a relatively low voltage environment, the circuit runs relatively stably, and faults are generally rare under normal usage conditions. However, over time or under harsh operating conditions, various faults may still occur on the circuit board (for a detailed explanation of the circuit board structure, please refer to the corresponding illustrations).

2. Brief Overview of Common Faults in LCECPU Circuit Board

1. Natural Aging of Electronic Components: This type of fault often occurs in elevators that have been in use for a long time. Due to the prolonged operation of certain electronic components on the circuit board, failures may occur, leading to the malfunction of specific functions of the circuit board, which in turn can cause elevator faults. Among these, electronic components near heat sources are more likely to age due to their prolonged exposure to relatively high temperatures.

2. Damage to Components Due to Overvoltage, Overcurrent, and Overheating: When overvoltage or overcurrent conditions occur in the circuit, or if the local temperature of the circuit board becomes too high, it can directly damage the electronic components on the circuit board, causing overall circuit board failure and ultimately leading to elevator operation issues. From the perspective of fault occurrence, this situation is more likely to happen in the power supply section.

3. Damage to Communication Chips: The communication chip is a key component that ensures normal communication between the LCECPU circuit board and other circuit boards of the elevator. If this chip is damaged, it will interrupt communication between the CPU circuit board and other circuit boards, preventing data transmission and command coordination, thus affecting the normal operation of the elevator.

4. Loss of Program or Damage to D7 Chip: The D7 chip stores important programs required for elevator operation. If the program in the chip is lost or the chip itself is damaged, it will directly prevent the elevator from starting and operating normally.

5. Insufficient Battery Power of D8 Chip: The battery of the D8 chip provides power support for the internal program storage. When the battery power is insufficient, it can cause the internal program of the chip to be lost, leading to elevator operation failures.

6. Printed Circuit Breakage: The printed circuits on the circuit board may break due to prolonged exposure to corrosive environments or vibrations during elevator operation. A break in the printed circuit can interrupt circuit connections on the circuit board, causing circuit board failures and preventing the elevator from operating normally.

7. Decreased Capacity of Surface-Mount Capacitors: If the capacity of surface-mount capacitors on the circuit board decreases, it can lead to intermittent elevator stoppage faults. Specifically, this manifests as the elevator stopping intermittently during operation, and after power cycling, the elevator may resume normal operation, but the stoppage fault will reoccur after some time.

8. Damage to Crystal Oscillator: The crystal oscillator is an important component for maintaining normal CPU operation. If the crystal oscillator on the circuit board is damaged, the CPU will stop functioning, and it can be observed that the CPU operation indicator light will no longer flash.

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