Figure 43. Power supply assembly Note When the control panel backlight is off, the +5V line is being signaled off at the control panel assembly by the control panel controller board. SPON is the scanner power-on signal sent to the scan engine power supply when the MFP is powered on by pressing the power switch on the print engine. See “Low-voltage power supply circuit” on page 78 for more information. 76 Chapter 5 Theory of operation C8523-90921