Fault case analysis of medical diagnostic X-ray machine —Two

Fault phenomenon: when there is no image in automatic perspective, there is no indication on the mA table.
Analysis and maintenance: when the fault mentioned above is good and bad, then you can choose to observe it manually. Turn on the KV, mA and select the minimum value to see if there are any similar failures. Boot, press the perspective key, the perspective mA to 1mA, perspective KV a little rise, each increase 5KV, stop a stop to observe the mA value and image stability, such as stability, and then increase the perspective KV. When the perspective KV rises to 100KV, the mA table pointer suddenly rushes to the top, and the image is gone, and there is a discharge sound in the diagnostic room. See the circuit diagram and analyze the top of the mA table for reasons:

1. mA indicator circuit problem;
2. problems in high voltage circuit.

According to the fault phenomenon, it is more likely to analyze the problems in the high-voltage circuit. The high voltage circuit is made up of high voltage generator, high voltage cable and ball tube. When checking, we usually check the high voltage cable first, then the ball tube and the high voltage generator.

The high voltage cables at both ends of the cathode and anode are respectively taken out from the high voltage generator and the ball tube to observe whether there are traces of discharge on the surface. When the anode cable is removed from the side of the ball tube, the high voltage insulating silicone grease on the cable head has turned black and is normally white. And the other parts of the cable head are normal. Then a megaohmmeter is used to measure the resistance between the high voltage cable head and the shielding layer, and there is no breakdown phenomenon. The fault is caused by the discharge of the cable head. After the cable head is processed, grease is recoated to restore the cable. Open the machine and remove the fault.

Author: X Ray Machine Accessories