HP LaserJet Enterprise 500 Maintenance Manual - Page 231

Printer Interface

Page 231 highlights

DC Power DC Power The power supply board contains two DC power supply systems for the printer. The first is a +5 V bus for logic. The second consists of +48 V and +8.5 V buses for the hammer bank and all motors. The +5 V supply has an isolated return line that connects to the +48 V return at the printer load. Both returns are tied together in a one-point ground. The +5 V power supply has its own inverter, separate from the +48 V and +8.5 V outputs. There is an opto-isolated input on the power supply that will shut down and latch off the +48 V and +8.5 V supplies unless it is pulled up to +5V with a 1K Ω resistor. This resistor is mounted on the controller board and may be pulled down or disconnected by software or internal cable interlocks. The +5 V output will remain stable for reporting and latching the fault condition. The return for this signal is the +5 V return. In addition, this shutdown circuit discharges and latches the +48 V down to a level lower than +15 V in less than 200 milliseconds and requires recycling of the circuit breaker (On/Off switch) to reset the latch. Loss of +48 V is seen by the EC and reported as a fault. Printer Interface The printer interface is the point where the data cable from the host computer plugs into the printer. The printer interface processes all signals and data to and from the host computer. The printer is equipped with Centronics® parallel, EIA®-232E serial, and EIA422B serial interfaces. The interfaces are mounted on the CMX controller board, and the interface cable connectors are accessible through a cutout at the rear of the card cage. These interfaces accept data in the U.S. ASCII protocol. Selection of the interface is controlled by configuration menus accessed at the control panel. It is possible to physically connect more than one interface, but only one interface at a time can be used electrically. 231

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DC Power
231
DC Power
The power supply board contains two DC power supply systems for the
printer. The first is a +5 V bus for logic. The second consists of +48 V and
+8.5 V buses for the hammer bank and all motors.
The +5 V supply has an isolated return line that connects to the +48 V return
at the printer load. Both returns are tied together in a one-point ground. The
+5 V power supply has its own inverter, separate from the +48 V and +8.5 V
outputs.
There is an opto-isolated input on the power supply that will shut down and
latch off the +48 V and +8.5 V supplies unless it is pulled up to +5V with a 1K
resistor. This resistor is mounted on the controller board and may be pulled
down or disconnected by software or internal cable interlocks. The
+5 V output will remain stable for reporting and latching the fault condition.
The return for this signal is the +5 V return. In addition, this shutdown circuit
discharges and latches the +48 V down to a level lower than +15 V in less
than 200 milliseconds and requires recycling of the circuit breaker (On/Off
switch) to reset the latch.
Loss of +48 V is seen by the EC and reported as a fault.
Printer Interface
The printer interface is the point where the data cable from the host computer
plugs into the printer. The printer interface processes all signals and data to
and from the host computer.
The printer is equipped with Centronics® parallel, EIA®-232E serial, and EIA-
422B serial interfaces. The interfaces are mounted on the CMX controller
board, and the interface cable connectors are accessible through a cutout at
the rear of the card cage. These interfaces accept data in the U.S. ASCII
protocol.
Selection of the interface is controlled by configuration menus accessed at the
control panel. It is possible to physically connect more than one interface, but
only one interface at a time can be used electrically.