One CTP troubleshooting example

In September 2001, this unit purchased a Sata Angel Lotem800v CTP device, and the author became one of its operators. In the past few years, although the device has been used in the course of such as automatic plate tilt, laser exposure scan interrupted halfway, and even the exposure of the drum off the plate, resulting in smashed printing plate and other failure phenomena, but under the meticulous maintenance of all relevant personnel , In a timely manner to find and troubleshoot various failures, which did not cause long-term shutdowns and affected production. Here, the author enumerates a typical failure, from the emergence of the fault, troubleshooting, repeated troubleshooting to complete elimination for several months. For this reason, the author records the troubleshooting process as follows and hopes to share it with peers.

Failure analysis

In early March of 2008, this CTP began to experience a distressing phenomenon: When the operator performed a quality inspection on the prepared thermal plate, it was found that there was a scanning dashed line on the exposure graphic, which appeared in many cases. Due to the change from negative image exposure to positive image exposure at the time of the map and the edge of the color patch, the new thermal plate was replaced and the scanning dashed line appeared on only one or two sizes of printing plates. Therefore, the doubt was concentrated on the new material. Photosensitive coating. After communicating with the plate manufacturer's technical staff, it is believed that the dashed lines appear in rows and are so neat that they should not belong to the issue of plate coating, but also exclude the squeeze friction and development brush of the drive roller on the plate during the development process. Negative effects.

Troubleshoot each laser

In the following month, the scanning dashed line appeared more and more frequently, and the CTP's rejection rate rose linearly. Through consulting with the Saijie engineers, it was learned that the laser beam in the laser beam of the CTP equipment may be damaged, resulting in a disorder in the scan sequence of some of the dots, resulting in a dashed line. Originally, Lotem800vCTP equipment uses 48 lasers for scanning exposure, the laser number is 0 to 47, each laser is controlled by a special circuit board through the optical fiber, 48 circuit boards are installed in the machine side in 4 rows, open the right side of the machine The door and a layer of dust cover can be seen. According to the engineer's telephone guidance, we started troubleshooting the laser.

In the Lotem800v operating system interface, open the following items one by one: "Utilities → Hardware → Expose system → Laser groups"; right click on "Lasergroup" and enter the laser beam data display interface: Firstexposelaseractive0
Lastexposelaseractive47

The original fixed use of 0 ~ 47 laser is divided into several segments, such as divided into 0 ~ 11,12 ~ 23,24 ~ 35,36 ~ 47 four segments, through the keyboard settings to shield out three of the laser, only select the remaining 1 Segment 12 laser scanning exposure, that is, the above data (0,47) were changed to (0,11), (12,23), (24,35), (36,47). Then observe if any scanning dashed lines appear on the exposed plate.

After multiple selection tests, we determined that the fault laser appeared in the range of 0 to 20 roads. To ensure the production cycle and continue to use CTP, we blocked 0 to 22 lasers and only used 23 to 47 lasers. jobs. In this way, the work efficiency of CTP has also dropped by nearly half, and the production time of a set of four-color heat-sensitive plates has been extended from the original 20 minutes to nearly 40 minutes.

The CTP equipment continued to use for half a year under this condition. On October 21, 2008, a power outage accident occurred on the workshop. After the power supply was restored, the CTP equipment was started. The dashed line of the exposure scan reappeared and was much worse than before. The actual CTP was Can no longer work properly. Two days after the Angels engineers arrived, after another exposure test, we made another argument for the reasons for the scanning dashed line.

Out of my mistakes

The previous investigation of various lasers was actually a misunderstanding. The engineer told us that there are still two master control boards behind the 48 Loiter800VCTP laser circuit boards. Here they are called I board and II board respectively. The I board manages 0 to 23 lasers, and the II board manages 24 to 47 lasers.

The problem lies in the I board. Due to the long-term work, the electronic components of the I board are aged and the performance is unstable. As a result, the exposure of the laser beam controlled by the I-beam causes exposure failure. With the prolonged use of the CTP, the phenomenon of failure gradually emerges. After the laser beam was checked last time, 0 to 22 lasers were shielded, and 23 to 47 lasers were used. Since the 23rd laser is managed by the I board, the CTP is still using two control boards I and II. At that time, the I board had not been exposed to obvious failures, but later the CTP suddenly lost power during the operation, which further damaged the electronic components of the I board that had already been aged, resulting in complete failure of the board and resulting in a lot of laser failure of the 23rd path. Scan the dotted line.

After listening to the analysis of the engineer, we looked at a record in the working log: On the night of December 8, 2007, the CTP interrupted its work during the automatic printing process and reported the following error message: "Expose started with no goodlasers, Expostoskfailed". At the time of opening the "Lasergroups" window bar, it was found that the "Exposediodes" (diodes means diodes) at the bottom left of the column showed values ​​of -1, -2, and the color was a warning red. Click "Resetdiodes" in the column and the value becomes 0.47. The color also returned to normal, exit the system, restart the CTP, and work normally.

This failure later appeared many times and was solved in the above manner. Now analysis, electronic components such as diodes on the control circuit board have reported aging warnings and must be reactivated by clicking “Resetdiodes” to work properly. This phenomenon does not have a major impact on the operation of the CTP. In-depth analysis. It now appears that abnormal diode data appears from time to time and is also a reaction associated with the failure of the control circuit board.

The cause of the failure was clarified, and 0 to 23 lasers were shielded. Only the 24 to 47 lasers controlled by the II board were used to scan exposure. The CTP operation was normal, but the working speed was reduced to 1/2 of the original. After the final replacement of the new control circuit board, laser work of 0 to 47 channels was resumed, and the CTP work efficiency was immediately increased to the original level, and no scanning dashed line was found. At this point, the CTP failure that has been plaguing production for half a year has been completely eliminated.

On the surface, it is just a simple process of replacing a control circuit board. However, the investigation and analysis in the “mistakes” before this time was not inconvenient. After all, in this process, we have the working principle and characteristics of the CTP laser beam. With a deeper level of understanding, we can say that we have accumulated useful experience especially for our future work.