Device model: KE-2020M

Description of the problem: KE-2020M machine stopped for a few days, and returned to the origin after restarting and reported that the Y-axis was overloaded, and the return to the origin failed. Sudden power failure of the placement head and LCD screen occurred when the operation returned to the origin. It was discovered that a safety trip at the back of the machine. Press the insurance back, power on again, and leave it for a period of time before performing the return to origin operation successfully. Later, it was found that the intermediate transfer motor did not move, which caused the board to stop at the junction of the board advance motor and the intermediate motor after entering the board, and the placement could not be performed.

Temporary measures: 

1. Switch to manual operation. It is found that both the board-in motor and the board-out motor can run in the factory, but the middle motor has not responded. The status display can be switched between ON and OFF, but the motor does not move.

2. Turn the transmission shaft of the middle motor by hand and find that the motor has a certain locking torque when the machine is powered on. After the machine is powered off, the transmission shaft can easily rotate.

3. The stepping motor driver board next to the transmission card has been replaced, and the fault remains.

4. Replace the entire transmission card, the fault remains.

Problem status: seeking help

The machine of KE-2020M stopped for a few days, and returned to the origin after restarting and reported that the Y-axis was overloaded, and the return to origin failed. Sudden power failure of the placement head and LCD screen occurred when the operation returned to the origin. It was discovered that a safety trip at the back of the machine. Press the insurance back, power on again, and leave it for a period of time before performing the return to origin operation successfully. Later, it was found that the intermediate transfer motor did not move, which caused the board to stop at the junction of the board advance motor and the intermediate motor after entering the board, and the placement could not be performed.

1. Switch to manual operation. It is found that both the board-in motor and the board-out motor can run in the factory, but the middle motor has not responded. The status display can be switched between ON and OFF, but the motor does not move.

2. Turn the transmission shaft of the middle motor by hand and find that the motor has a certain locking torque when the machine is powered on. After the machine is powered off, the transmission shaft can easily rotate.

3. The stepping motor driver board next to the transmission card has been replaced, and the fault remains.

4. Replace the entire transmission card, the fault remains. The measurement found that the signal of the middle transmission motor is purely a Carry PCB. After the white cable is connected to the transmission card, it is sent from the 4pin square connector to the next stepping motor driver board. Do any processing on the transfer card. My heroes, from which board does the control signal of the intermediate transmission motor come from? What could cause this failure? Thank you!

After a long toss, the problem was finally solved. Since there is no manual information related to the machine, we can only infer the direction of the intermediate motor control signal bit by bit.

The positioning process is as follows:

1. Find a person to cooperate and connect to the white data line containing the control signal of the intermediate stepper motor on the transmission card by pulling before and after the machine, and make sure that the data line is connected to the XMP Relay PCB (XMP Relay PCB);

2. Pull out the control signal line (4pin) of the middle motor drive board, input a 5V 1KHz sine wave signal and a square wave signal from pin 1 and 4 respectively, and then pull out the data of 3 XMP boards (two main and one pair) Use an oscilloscope to detect the waveform signal on the pins of the data line connector. Finally, a 5V 1KHz sine wave signal and a square wave signal are measured on the data line connector of the XMP sub-board, indicating that the control signal of the middle motor comes from the XMP sub-board ；

3. Pull out the XMP main and sub-board from the chassis, connect the XMP sub-board data cable, search for the waveform signal on the XMP sub-board, and finally detect sine wave and square wave signals on the corresponding pins of the two 485 chips;

4. Turn the multimeter to the short-circuit detection position, point one test pen on the data input pin of the 485 chip, and the other test pen slides on the pin of the nearby logic chip. It is known from the buzzer of the multimeter, The data input of these two 485 chips comes from the logic chip. Finally, the general transmission path of the control signal of the intermediate stepper motor is obtained: logic chip --->485 chip --->c Carry PCB --->stepper motor drive small board --->intermediate motor. There are two sets of control signal lines for the middle motor, which are respectively transmitted through two 485 chips. It is estimated that one set of signals controls the motor to rotate forward, and the other set of signals controls the motor to reverse.

5. The problem is now clearer. Since the motor control board and the transmission card have been eliminated by the replacement method before, the data transmission line is also normally connected, so the problem may only be on the 485 communication chip or the logic chip. The principle of difficulty is to replace the two 485 chips (because I don’t know which one is the forward control channel, and the reverse control channel over there, I just replaced both of them), connect the XMP main board and the auxiliary board and reinsert it into the machine frame. Reconnect all the data cables, turn on the power, and after returning to the origin, select manual control--->transmission system--->individual control--->intermediate motor, haha, the intermediate motor that strikes finally runs normally.

Summary: The failure and damage of the 485 communication chip of the XMP sub-board caused the control signal of the middle stepping motor to be unable to be transmitted to the motor drive board, which eventually caused the middle motor to stop running. The whole positioning process is difficult and time-consuming. Because there is no relevant information about the machine manual, I would like to ask you a copy of the manual file of the JUKI KE-2020M machine. I hope that the heroes who own this manual can be generous. Unpack, thank you!

---Becky Su

becky@hysmt.cn