Troubleshooting of irregular automatic power failu

2022-08-21
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Troubleshooting of irregular automatic power failure of die-cutting machine

the boster die-cutting machine (sp102e Ⅱ) used by our company has the fault of sudden power failure and automatic power failure in production, and it is very irregular. The specific performance is: in case of failure, the main power light of the electrical cabinet is on, the frequency converter is normal, the machine light is off, the display screen is black, and there is no response by pressing any button or restarting the power supply, so we can only wait for the machine to call by itself. This fault occurs during production and standby idling. After checking the electrical cabinet, we found that in case of failure, the contactors K37, K38, K50 and K52 do not engage, only four indicators on the main circuit board A105 are on (the lowest light of A105 is also on in normal conditions), and the indicators on the circuit board A107 are not on (A6 and A8 indicators are on in normal conditions)

at first, it was suspected that it was caused by peripheral overload, unstable power supply and poor contact of the plug. It was found that the lights of power supply G1 and G2 were on, and the voltage was +5v, +24v, +15v; The peripheral air compressor and frequency converter have no abnormal reaction such as overload, and the plug is not loose. It is also suspected that the performance of a component of the circuit board will be reduced due to the temperature rise, so take anhydrous alcohol and gently wipe it one by one, but there is no reaction

after carefully checking the drawing, we know that A109 board is 115VAC input board (with 2 boards), A107 board is 115VAC output board, and A105 board is mainboard. Its workflow is shown in Figure 1

so we checked again as follows

(1) check the key switch S9 and find it is normal. Due to the impact of the oil crisis in the 1970s and in order to improve the combat effectiveness of military aircraft and the reliability of civil aircraft, the two boards of A109 are exchanged. The fault still exists, indicating that the A109 board is normal

(2) measure A6 and A8 points on A107 board, and there is no 115VAC output. A20 on A105 motherboard has no 24VDC output. Consult the manufacturer, and it is suspected that the A107 board darling drive element is broken, or there is a problem with the CPU chip and memory on the A105 motherboard, or the a10767 glass fiber reinforced cement light porous partition board and A105 board have poor contact between the data line and the control line since this year, resulting in no output of A6 points

after inspection, the data line and control line between A107 board and A105 board are in good condition. Short circuit the 13 and 14 ends of K37, measure 24VDC and return to 734he board. The lamp is on, the display screen is on, but the display parameters are incorrect, and the machine cannot be started, indicating that there is a high possibility of problems with A105 main board. Replace the main board, but then the fault occurs again

(3) to be on the safe side, the A107 board was replaced, the shielding of all signal wires was checked, and the grounding wire was re introduced to eliminate electromagnetic interference, which was still useless

finally, recheck the power supply. After measurement, it is found that the voltage of +5v, +24v, +115v is low, and it is adjusted to 5.1V, 24.5v, 118v. Repeatedly unplug and test the machine. It is found that the A107 board and A105 board are unplugged and turned on. Sometimes the machine cannot be started. At this time, the machine can be turned on again by plugging the board hard. This indicates that there is a poor contact phenomenon. After the main board problem is eliminated, it is concluded that the problem is on the back plate 734he. Confirm the material hardness with the pressing depth of the pressure needle. The board is 4 times thicker than the ordinary board, and the signal and data are transmitted by it. After replacing the board, the problem can be solved. Since then, the machine has been running normally

the irregular shutdown fault of the die-cutting machine in this case is mainly caused by the low power supply voltage and poor contact of the backplane. Combined with the actual situation, the author believes that when the machine breaks down in the future, we should first check the power supply voltage to ensure that the voltage meets the standard requirements of the manual, and do not arbitrarily reduce the voltage, so as not to cause system instability or damage electronic components. Secondly, for the problem of poor contact, don't fall into the mindset. You should study repeatedly according to the drawings, find out the connection between the fault phenomena, list the possible causes and check them one by one

information source: Printing Technology

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