HP FAX-750 Service Manual - Page 145

3.8 Sensor Operational Check n Function This function allows you to check that the seven sensors (document front sensor, document rear sensor, cover sensor, paper ejection sensor, paper-edge sensor, ribbon sensor, and hook switch sensor*) operate correctly. (*In the FAX-910, the hook switch sensor serves no function.) n Operating Procedure (1) Press the 3 and 2 keys in this order in the initial stage of the maintenance mode. The equipment sounds 1100 Hz and 400 Hz tones cyclically through the following volumes for testing the speaker. If the sensing status are as listed below, the LCD will show the following: "FRERCJMPHRX 1" on the FAX-910 "FRERCJMPHRXHK 1" on other models In this area a numeral appears, indicating the number of communications records printed out at the factory for testing. Given below is the relationship between the LCD indication, sensor name and sensor status. LCD Sensors Sensing status FRE RC JM PH RX HK Document front and rear sensors Cover sensor Paper ejection sensor Paper-edge sensor Ribbon sensor Hook switch sensor No document detected. Recording paper cover ASSY closed. No paper jam. Recording paper loaded or paper front cover opened. Ribbon cartridge loaded. On-hook state. (2) Change the detecting conditions and check that the displayed letters disappear. For example, insert a document through the document front (or rear) sensor and check that the "F" ( or "E") of the FRE disappears. (3) To stop this operation, press the Stop key. The equipment beeps for one second and returns to the initial stage of the maintenance mode. V - 52