Lexmark W820 Service Manual - Page 272

4025-Finisher Wiring Diagram Notations The wiring diagrams presented in this manual use the following circuit notations to describe components and signal paths within the printer. A PLUG. A JACK. CONNECTION OF PIN 15 OF CONNECTORS P28 AND J28. THE SIGNAL NAME OF A WIRE. THE VOLTAGE MEASURED WITH THE NEGATIVE PROBE OF THE METER ON SG. THE VOLTAGE VALUE OF A SIGNAL / = The voltage goes LOW when the signal is ON. In this case, the HEAT signal is ON, so the normal voltage of 4.2 V dc drops to 0 V dc. GND GROUND. SGND SIGNAL GROUND. PGND FRAME GROUND. RTN RETURN. There is continuity between SG and RTN. Continuity between FG and SG depends on circuit specifications. $ $ in a signal name indicates the signal is coming from the MCU CPU. # # in a signal name indicates the signal is going to the MCU CPU. TTL TTL displayed in the HIGH level or LOW level columns of the signal tables indicate the signal is ECL_CMOS compatible. #$ Interactive communication signal. ## Analog signal. 5-12 Service Manual