Number of views：2187order Release Date：2020-11-26

Firstly, it is caused by poor power supply circuit: it is manifested as no response when pressing the panel buttons, and the indicator light does not light up. First, check whether the 12V voltage is good, and then check whether the 5V voltage is good. Because the working voltage of the signal processing chip in the A/D drive board is 5V, when looking for the fault of not being able to turn on the machine, first use a multimeter to measure the 5V voltage. If there is no 5V voltage or the 5V voltage becomes very low, then one possibility is that there is a problem with the input stage of the power supply circuit, that is, there is a problem with the power supply part that converts 12V to 5V.

This type of malfunction is very common, usually caused by fuse burning or voltage regulator chip failure. Some machines have built-in switch power supplies that output two sets of power supplies, one set is 5V for signal processing, and the other set is 12V for providing high-voltage board backlight. If there is a fault in the circuit of the switch power supply, it may cause both sets of power supplies to not output. Another possibility is that the 5V load has increased, causing the 5V voltage to be pulled very low. In other words, there is a problem with the signal processing circuit in the later stage, some circuits are damaged, causing the load to increase. The 5V voltage is pulled very low, and the faulty components in the later stage are checked one by one. After replacing the faulty components, the 5V can be restored, and the fault is generally solved. It is also common to encounter situations where the 5V voltage is restored but the power cannot be turned on properly.

There are also various reasons for this situation. On the one hand, the program of the MCU may be flushed, which may cause it to not start up. On the other hand, the MCU itself may be damaged, such as the I/O port of the MCU being damaged, making it impossible for the MCU to scan the keys. When encountering this kind of fault caused by the MCU, it is useless to look for hardware problems. Even if you replace the MCU, it cannot solve the problem because MCU requires programming and writing. In the case where we cannot find the original AD driver board to replace it, we can only find another way to find a replaceable A/D driver board