[惠普] HP/惠普 P75050 P77740 P77750 P77760 页宽打印机英文维修手册

The AC control module performs the following functions related to the heating elements in the air flow assembly:

a. The voltage of the outlet, which the printer is attached, is monitored to ensure the printer remains operational, even in a low-quality-power environment. This is done by instantly shutting off heater power until the minimum voltage threshold is met. Hysteresis is included to avoid rapid fluctuations in voltage.

b. This circuit generates a frequency modulated signal that is sent across the isolation barrier, and interpreted by firmware in the engine.

– Isolates the low voltage heater control signals from the high voltage AC power that is applied to the heater. This is a safety feature to ensure line transients (i.e. lightning) aren’t coupled into the low voltage system, which could cause damage to the printer or user.

– Using relays, the heating element configuration is changed between series and parallel, in coordination with applied voltage. This is done to have a predictable temperature profile that is functional across the full range of worldwide voltages (90-240VAC).