1.Make sure the printer is turned off.

2.Disconnect the V-connector from any twin-axial cables (but leave it connected to the interface). Since the interface transmits data to itself during this test, leaving it connected to the twin-axial cable could disrupt the twin-axial system.

3.Write down the positions of switches 1, 2, and 3 (you need to return them to their initial positions after the test is completed). Then turn switches 1, 2, and 3 on. This selects cable address location 7. Address 7 is used only during interface diagnostics and interface diagnostic loopback.

4.Turn on the printer; then press the TEST button on the interface. The printer then performs the test and prints the following:

TEST SEQUENCE COMPLETE

The printer performs the test sequence over and over; error messages are printed between the TEST SEQUENCE COMPLETE” messages.

5.After you are finished running the test, turn the printer off and reset switches 1, 2, and 3 to their original position.

INTERFACE DIAGNOSTICS ERROR MESSAGES

The error messages and explanations are listed below.

If an error occurs, the following tests may not be performed.

OUTPUT TIMING ERROR

The twin-axial output circuits are not responding to the microprocessor as expected. This could be caused by a non-functioning circuit or by a termi-

nated cable not being attached to the interface.

UNEXPECTED VECTOR or IMPROPER BYTE VECTOR

The interrupt handling process received an improper interrupt value. Possible causes are initialization problems, non-functioning circuits, or microprocessor problems.

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