NCR 7156, Service Manual

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7156 Service Guide Chapter 14: Replacing the Print Mechanism
September 1998 133
Note: This wiring is required only on older PC boards.
If you are replacing the PC board because of a failure, read the following information. If
you are putting the PC board back in after removing or replacing another item, go directly
to step 1. Be sure to read the Caution first.
Order the common PC board to replace either the older RS-232C or the older LCSIO (RS-
485) PC boards. The common PC board is populated differently for each interface.
When the common PC board replaces the LCSIO (RS-485) PC board with the MICR check
reader option, the MICR amplifier board must also be removed. See “Removing the MICR
Amplifier Board: LCSIO (RS-485) Models” in chapter 9 for more information. Three
extender cables are available in a kit that must be used to connect the following three
cables to the common PC board:
•
MICR Read Head Cable
•
MICR Buckhead Cable
•
MICR Solenoid Cable
Note: In addition, a longer cable for the front LED sensor is included in the kit to replace
the current cable which is not long enough to connect to the new common PC board.
See “Appendix C: Common PC board” for more information about the extender cables. See
the Parts Information Manual for the kit number.
Caution: Electro Static Discharge may damage the PC board. Wear a grounded wrist strap
and use a static mat or other ESD protected work surface whenever you work with the PC
board.
1. Position the PC board next to the printer, but don't put it in yet.
2. On models with the MICR amplifier board, route the paper feed motor wire through
the clip in the base so it doesn't go over the top of the MICR amplifier board (if not
already done).
See the illustrations in the following sections: “Replacing the Print Mechanism” and
“Replacing the MICR Amplifier Board: LCSIO (RS-485) Models,” both in this chapter.
3. Separate the two sets of wires of the interconnect cable connecting the MICR amplifier
board and the PC board.
The MICR amplifier board is only on certain older LCSIO (RS-485) models. The wires
need to be routed separately to avoid electromagnetic interference.
4. Reconnect the MICR interconnect cable to (J12) and the logic ground to (J13) as shown
in the following illustrations.
5. Seat the board in the slots in the base of the printer.
6. Replace the rest of the connectors as shown in the following illustrations.
7. Route the set of three wires of the interconnect cable above the tab that protrudes from
the thermal mechanism and route the set of two wires below the tab as shown in the
following illustrations.