Diagnostic Control Unit (Dcu); Connecting The Dcu; The Dcu's Operating Modes - Xerox DocuPrint P1202 Service Manual

5.4 The Diagnostic Control Unit (DCU)
The Diagnostic Control Unit (DCU) (600T80340) is a pocket-sized test instrument that enables a variety
of diagnostic tests and provides a coded digital readout which is used to monitor printer functions.
NOTE: Ensure that you use the correct DCU overlay for the printer you are servicing. The P1202 printer
requires the use of the Model : ML-6000 Series DCU overlay.

5.4.1 Connecting the DCU

Follow the instructions below to connect the DCU to the Engine Controller PWB.
1 Switch off the printer and disconnect the AC power cord. NEVER ATTEMPT TO CONNECT THE
DCU WHILE THE PRINTER POWER IS ON.
2 Remove the face up Cover.
3 Remove the front cover.
4 Remove the bottom panel.
5 Install the front cover.
6 Plug the DCU's four-pin connector into Controller Board connector J6 or into the Engine
Controller PWB connector CN2.
7 The Front Cover / Print Cartridge Interlock Switch must be actuated to perform the DCU
tests. The Print Cartridge must be in place and the Front Cover closed or the interlock cheated to
run the tests.
8 Reconnect AC power and switch on the printer.

5.4.2 The DCU's Operating Modes

Operation of the DCU is simpler than it might appear from the variety of indicators and labels on the
DCU's face. (see Figure 5.4.2a). Only some of them are involved at any given time, depending on the
DCU's current operating mode.
The DCU has two operating modes:
• Status Mode
• Diagnostic Mode
Two LEDs on the upper left of the DCU's face correspond to the two modes. One or the other will always
be lit to indicate the DCU's current mode.
In both Status and Diagnostic modes, double-digit numeric codes are displayed in the readout window
on the upper left. The meaning of any particular code depends on the DCU's current mode. The two
modes of operation and the associated codes are explained in the next two sections.
NOTE: If there is any discrepancy between the information here and labels on the DCU, ignore the DCU
labels and follow this information.
General Procedures and Information
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