Epson ET-8500 and ET-8550 Paper Jam Issues – PE Sensor Troubleshooting and Testing Guide

Question:
I have an Epson ET-8500 printer experiencing recurring jam issues. My symptoms differ from those described in your videos but always involve paper curling and jamming right after the duplexer near the PE sensor. When printing, the printer draws paper halfway, stops, then makes a crinkling noise and reports a jam. Interestingly, the printer's paper feed cleaning function always works perfectly without jamming. I managed to temporarily fix the issue using compressed air around the PE sensor area, but I'd appreciate it if you could explain exactly how you test the PE sensor, as I couldn't find detailed instructions in your videos. Could you elaborate on the procedure?

Answer:
Thank you very much for reaching out with such detailed information! I'm truly sorry for the delay in responding—I understand how urgent and challenging printer problems can be, and your detailed description deserved careful consideration. At BCH Technologies, we deeply appreciate your continued engagement and support, particularly through our YouTube channel. Your insights significantly help us enhance our troubleshooting resources and technical content.

Understanding Your Issue: Epson ET-8500 Paper Jam and PE Sensor Role

The PE (Paper Entry) sensor is critical in detecting paper movement into the printer and managing precise paper handling. Your described symptoms—paper partially feeding, stopping, crinkling noises, and subsequent jams—strongly suggest the PE sensor may have contamination or malfunctioning issues.

Why the Paper Feed Cleaning Function Works but Printing Fails

The cleaning function typically bypasses some sensor checks, specifically those for alignment and skew detection, using a simplified, non-printing feed path. Hence, it doesn't trigger jams like standard printing modes that rely heavily on accurate sensor feedback.

How to Test the PE Sensor on Epson ET-8500/ET-8550 Printers

Passive (Observation) Testing:

• Basic Feed Test: Insert paper and observe printer behavior. Consistent stalls or no attempt at paper retraction typically indicate PE sensor issues.

• Manual Rear Feed Test: With the duplexer removed, feed paper manually. If the printer pushes paper slightly backward then reports jams consistently, the PE sensor might be failing or obstructed.

Active (Electrical) Testing:

• Multimeter Diode Test (Power Off):

  • Unplug the printer and access the PE sensor PCB.

  • Use a multimeter in diode mode to check the IR LED within the sensor. You should see a voltage drop (~1.1V) indicating normal LED function. However, note that inline resistors or capacitors may skew readings.

• Live Voltage/Oscilloscope Test (Advanced):

  • Power the printer carefully and use an oscilloscope or multimeter to measure voltage changes on the sensor's phototransistor output.

  • A functioning sensor typically toggles between 3.3V (unblocked) and ~0V (blocked).

  • Caution: Conduct this test cautiously to avoid electrical damage or injury.

Recommended Steps for Long-Term Resolution

• Continue using compressed air periodically, as you've already found this method effective.

• If problems recur, consider partial disassembly for visual inspection of the PE sensor and cleaning more thoroughly.

• Check for any mechanical obstructions or deformities along the paper path near the PE sensor location.

Addressing printer problems can be inherently complex due to their physical and mechanical nature. Thus, remote troubleshooting has practical limitations. BCH Technologies offers comprehensive in-person evaluation and repair services through our local diagnostic facility. Our service is in high demand and operates on a first-come, first-served basis, meaning it may take several weeks before an appointment becomes available. We clearly outline procedures for repairing entire printers or specific components but acknowledge our rates might not fit every situation. Therefore, we strongly encourage you to explore additional self-help resources online. Our extensive library of troubleshooting videos available on our YouTube channel provides detailed guidance on numerous printer issues. You can quickly locate specific tutorials by using the search icon next to "About" on the right-hand side of our YouTube menu bar. Given our extensive catalog of videos created over the years, utilizing the YouTube search function will efficiently guide you to the most relevant content and possibly suggest helpful videos from other creators as well.

Thank you once again for your thorough description and for supporting BCH Technologies. Your valuable feedback and inquiries directly contribute to improving our knowledge base and future video content!