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PADPRINT
NOTEBOOK Useful Tips & Information © ITW Trans Tech An Illinois Tool Works Company |
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 ELECTRONICS TROUBLESHOOTING: PLC Symptom Checklist 1. Locate the PLC on your machine. Exact location varies by machine model; usually it is inside the drawer on Sealcups or under the top cover on Combis. On Carousel printers, PLCs are inside the back panel. 2. Notice the LEDs that are lighted. A completed circuit is indicated by a lighted LED; an incomplete circuit will have no light. 3. Write down the numbers. Make a list of all the LED numbers and indicate which ones are lighted first. 4. Check the manual. Refer to the PLC electrical schematic drawings in the operator's manual. If you can't find your manual, call the ITW Trans Tech service department for help. We can also send you a replacement manual or spare parts list for future use. 5. Cross-check the numbers with the functions. Each LED number corresponds to a specific machine function. As the machine cycles, the PLC receives a message from each sensor and displays a lighted LED to show it. If a circuit is incomplete, the LED will show no light. 6. Check troubleshooting charts in the manual. The charts cover most common issues that occur. If that fails, call our Service Department at 630.752.4000, extension 5181. IN THIS ISSUE: |
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Reading Your PLC's Pulse
ON THE rare occasion that your machine may not be running properly,
a good place to start in the troubleshooting process is to look at the programmable logic controller (PLC). This component is the brain center of the pad printer that sends signals to motor drives and valves, then receives signals back from switches and sensors on the machine. By systematically checking these inputs and outputs, you can read the "pulse" of your machine to narrow down the possibilities. Once the most likely fault is identified, the answer is much closer.
What It Needs Depends On What Logic State It's In
A light-emitting diode (LED) will light up to indicate each signal received as the machine cycles through the program logic. By reading these LEDs, the problem can be isolated and traced with some detective work.
For example, on a Sealcup 90, if the number 15 LED is off, the fault may be one or both of two things: (1) swing guard safety door is not properly closed or (2) ink cup is not properly locked. Once both of these are accomplished, the LED will go on and that possible fault will be eliminated.
Most issues can be easily resolved simply by cross-checking the LED number with the schematic drawing shown in the machine operator's manual. Our service technicians can then walk you through the process over the phone and thus avoid a costly service call or unnecessary downtime.
Shown below: standard Combi PLC (Keyence) located inside and to rear of machine with cover panel removed; above, standard Sealcup PLC (Mitsubishi) located at rear of machine with service drawer pulled out.
For other Frequently Asked Questions about machine service issues, click here or to contact us click here.
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