Star Micronics LC-8521, Technical Manual

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1. Troubleshooting Procedures
Troubleshooting is never easy because various problems arise depending upon the particular location of the breakdown.
The following procedures should be taken in making repairs.
(1) The first method is to make repairs through unit replacements. The two display codes appearing in the flow chart
are defined as follows:
1) indicates main logic board replacement; and 2) indicates printer mechanism replacement,
to be carried out if the problem has not been corrected.
1) Main Logic Board Replacement
2) Printer Mechanism Replacement
Check again at this time whether the replaced unit is malfunctioning. (This is done to rule out trouble caused by improper
contact of connectors.)
Replaceable units consist of the following:
•
Power supply unit
•
Main logic board
•
Printer mechanism
•
Control panel board
In replacing these units, always refer to the unit replacement priority chart.
(2) The second method is to make repairs by parts replacement to replace defective elements inside a particular unit.
(Note 1) Before starting to repair, be sure to check visually the contact of the connector and the mounting of the IC in
the IC socket.
(Note 2) Always turn off power source and remove power plug before replacing any units or parts.
(Note 3) All check items shown in the flow chart must be checked. Otherwise, newly mounted parts or units may become
damaged.
(Note 4) If, in the process of making repairs, there is any confusion about proper procedures, restart the job from the
beginning.
(Note 5) Be careful to avoid injury from static electricity when handling ICs and main logic board.