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TTP-243 Plus/ 243E Plus/
342 Plus Bar Code Printer
4.7 Black Mark Sensor / Gap Sensor (Receiver) Replacement
Black mark sensor is reflection type sensor. It is connected to JP4 (3 pin connector). A
multi-meter is used to measure the signal of Pin2 to see if there is voltage variation
when black mark is detected. Before conducting the test, please issue the BLINE
command first. The printer will switch from gap sensor to black mark sensor. If there is
no voltage variation, please follow steps below to replace the black mark sensor / gap
sensor (receiver) PCB.
1. Turn off the printer power.
2. Remove the power cord and RS-232 and/or parallel port cable.
3. Open the top cover of the printer.
4. Remove the printer front panel. (Cf. Fig. 3.14)
5. Remove the two screws and the metal cover. (Cf. Fig. 3.15)
6. Release the cable tie and remove the peel-off sensor connector. (Cf. Fig. 3.16)
7. Remove the screw on the PCB of peel-off and cutter connector.
8. Remove the screws in the lower left, lower right corners of the main mechanism. (Cf. Fig.
3.17)
9. Remove all four screws of the internal label roll mount. (Cf. Fig. 3.18)
10. Move the mechanism in the label feed direction about 5 mm.
11. Take out the internal label roll mount and remove the connector. (Cf. Fig. 3.19)
12. Remove the screw of ground wire on the mainboard.
13. Remove all the connectors on mainboard. (JP1, JP2, JP3, JP4, JP5, JP6, JP7, JP11, JP7,
JP9, JP12)
14. Take out the mechanism.
15. Remove one flat tap screws and black mark sensor PCB.
Fig. 4.10 Black Mark Sensor and Gap Receiver Sensor
16. Reassemble the removed parts in the reverse order of removal.
4.8 Ribbon Sensor (Receiver) Replacement
1. Turn off the printer power.
2. Remove the power cord and RS-232 and/or parallel port cable.
3. Open the top cover of the printer.
4. Remove the printer front panel. (Cf. Fig. 3.14)
