NCR 7156, Руководство по эксплуатации и устранению неисправностей

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Chapter 2: Troubleshooting 9
printer and the monitor, and an angular orientation of the monitor to
the printer.
Improper System Ground Bonding
The metal structures and the logic and power grounds in the printer
must be securely bonded together and electrically connected to the
system ground at the host. The bonding path includes the
communication cable connecting the printer to the host.
Ground Testpoint (GND)
Power
Ground
Testpoint
(PGND)
To test the ground bonding, remove the top cover of the printer and
disconnect all cables, including the power supply, except the
communication interface which is to be connected as normally
required between the printer and the host. Measure the resistance
between the power ground (PGND) or logic ground (GND) and the
control board’s steel shield with the interface cable still connected to
the printer and the host
. The test points are shown in the illustration
above. The exact location of test points may vary depending on your
printer model. The resistance must be less than 5 ohms; if the
resistance is greater then 5 ohms, repair the open fault and then repeat
the MICR read test.