Epson TM-T20IV error lights and printing problems: fixes

CauseThe paper end sensor found no paper and the printer stopped printing.

Fix

1. Open the roll paper cover and remove the empty core.
2. Drop in a new roll so the paper comes off the underside of the roll towards the front.
3. Pull out a little paper and close the cover. The printer goes back online.

Paper LED on while paper remains? Near-end detection is enabled and the roll is nearly empty.

CauseThe roll paper cover was opened during printing, or the print head or motor driver got too hot. These errors clear on their own once the cause is gone.

Fix

1. Press the roll paper cover down until it is fully closed.
2. If the cover was closed, let the printer rest. It continues when the head has cooled down.

CausePaper or a foreign object is caught in the autocutter. The blade cannot return to its home position and locks the roll paper cover.

Fix

1. Switch the printer off.
2. Slide the cutter cover on the front of the printer towards you to open it.
3. Turn the knob until a triangle appears in the opening. This returns the blade to its normal position. The steps are engraved on the back of the cutter cover.
4. Close the cutter cover.
5. Open the roll paper cover, remove the jammed paper and any scraps, then close it. The error clears.

CauseAn internal fault, for example a memory error or a supply voltage far too high or too low.

Fix

1. Switch the printer off at once.
2. Check that it runs on the Epson AC adapter supplied with it, and that the DC plug is fully inserted in the connector marked 24V.
3. Switch the printer on again.
4. If the Error LED flashes again, the printer needs service. Contact us with the serial number from the nameplate on the side.

Long solid black areas, such as big logos or black bars, can trip the overcurrent protection and cause uneven print or a low voltage error. Epson's limit is about 30 mm of print length at 80 % black and 20 mm at 100 % black.

CauseThe paper is caught in the paper path, or paper dust on the platen roller makes the paper feed unevenly.

Fix

1. Open the roll paper cover. Never pull jammed paper out by force.
2. Remove the jammed paper. If the cover won't open, use Fix 3.
3. Clean the platen roller with a cotton swab moistened with water. Switch on only when it is completely dry.
4. Reload the roll and close the cover.

CauseThermal paper reacts to heat on its coated side only. A roll fitted the wrong way round leaves the receipt blank. Pale or streaky print usually means a dirty thermal head, unsuitable paper or a low print density.

Fix

1. Blank receipt: turn the roll round so the paper comes off the underside of the roll towards the front.
2. Faint or banded print: switch off, open the cover, let the head cool and clean the heating elements of the thermal head with a cotton swab moistened with ethanol or isopropyl alcohol. Epson recommends this about every three months.
3. Use thermal paper to Epson's specification (53 to 75 µm) that is not pre-printed on the thermal side.
4. Still pale? Raise the print density in the TM-T20IV Utility. This can slow printing down.

After a long pause with paper loaded, feed about 40 mm of paper first to avoid creased, light print.

CauseThe printer works, so the problem is on the Windows side: no Epson driver, the wrong port, or a queue added while the printer was offline.

Fix

1. Make sure the cover is closed, paper is loaded and the Error LED is off.
2. Check that the EPSON Advanced Printer Driver 6 for TM-T20IV is installed. If not, install it from the Epson download page.
3. Open Start › EPSON Advanced Printer Driver 6 › EPSON APD6 - TM Printer Settings, select the printer and check that the port type matches your cable: USB or Serial.
4. Unplug the USB cable and plug it in again. Windows can only add the USB printer while it is online.
5. Print a test page from Settings › Bluetooth & devices › Printers & scanners, and check that your POS software sends to the TM-T20IV queue.

All driver steps are in Install the Epson receipt printer driver on Windows.

CauseOn serial, the computer and printer use different communication settings; by default the printer prints "?" for data it can't read. A generic Windows driver can also garble text.

Fix

1. Serial: set the same values in the driver or POS software as in the printer. The factory settings are 38,400 bps, no parity, DTR/DSR handshaking and 8 data bits. The self-test printout shows the printer's settings.
2. Print through the Epson APD6 driver, or a POS app that supports ESC/POS, rather than a generic text driver.
3. Wrong special characters only: check the code page, PC437 by default, in the TM-T20IV Utility.
4. To see exactly what the printer receives, use hexadecimal dump mode: open the cover, hold Feed while you switch on until the Error LED lights, then close the cover. Switch off to leave the mode.