Chapter 3: Diagnostics; Level 0 Diagnostics - NCR 7156 Service Manual

7156 Service Guide

Chapter 3: Diagnostics

The following diagnostic tests are available for the 7156:
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Level 0 Diagnostics

The printer automatically performs level 0 diagnostics when it is put on-line. Level 0
diagnostics comprise the following actions:
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If the printer has not been turned on before, or a new EEROM has been installed, the
default values for the printer functions will be loaded into the EEROM during level 0
diagnostics. This action will be signaled by two beeps (RS-232C models only). These values
can be changed in level 1 diagnostics. See "Level 1 Diagnostics" for the functions and their
settings.
If the printer (RS-232C model) continues to beep twice each time it is turned on, it is an
indication that the EEROM has failed.
When the last step is complete, the Paper Feed button is enabled and the printer is ready
for normal operation. Information about the tests is available to the communication
interface through the commands.
Level 0 Diagnostics
Performed during the startup cycle
Level 1 Diagnostics (setup mode)
Available in a dedicated environment and accessed through the DIP Switches
Level 2 Diagnostics
Performed during normal operation
Level 3 Diagnostics
Maintained during normal operation and printed in the print test
Print Test
Performed in off-line mode
Motors and solenoids are turned off.
Microprocessor timing is checked, CRC check of the firmware ROM is performed,
external RAM is read.
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The green LED on the slip table flashes once if this action succeeds.
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Level 0 diagnostics stop if this action fails. Failure is indicated by the printer going
dead: knife and printhead do not home, the platen does not open, LEDs are not lit,
the printer is unable to communicate with the host computer.
Knife is homed. A fault condition is caused if this action fails.
Slip platen is opened.
Slip printhead is homed. A fault condition is caused if this action fails.
The status of all sensors is checked, and the status bytes are updated.
September 1998
Chapter 3: Diagnostics
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