CYLINDER AS 1678161 - Caterpillar

Introduction
This instruction provides the necessary information to replace the earlier design discrete component regulator with a new integrated circuit (IC), base plate, diode trio and hardware.The earlier regulators have separate transistors, diodes and other components mounted on a circuit board covered with an RTV-type coating. Both the new diode trio and the new regulator must be installed to replace this old type of regulator. New mounting holes must be drilled into the alternator housing housing to attach the new components.Refer to the table "DISCRETE COMPONENT TO INTEGRATED CIRCUIT REGULATOR UPGRADE" for a list of affected part numbers and new replacement part numbers.Do not perform any procedure, outlined in this publication, or order any parts until you read and understand the information contained within. Installation Procedure
1. Hold shaft by placing a 5/16" hex drive in the end recess. Remove shaft nut, washer, pulley, and fan to provide access to the thru bolts.2. Remove four thru bolts (22) from alternator and separate drive end assembly (with rotor) from rectifier end assembly. This is necessary to allow complete removal of metal shavings that will be created when new holes are drilled.3. Cover the open end of the rectifier end bearing with tape to keep shavings from getting in the bearing grease.4. Remove end plate (23) and rectifier cover (24) from rectifier end assembly by removing attaching screws (25).
Mark all wire locations before disconnecting for reference at assembly.
5. Remove nuts from rectifier bridge terminals and inside of "R" terminal (H) to disconnect three long, identically colored leads to regulator. Some units may have a separate lead between the "R" terminal and a rectifier bridge terminal. If so, remove this lead also.6. Place nuts loosely back on "R" terminal (H) and on rectifier bridge terminals to hold other leads in place during repair. If old regulator has a sense lead connected to the heat sink attaching screw, remove screw, flat washer and insulator to disconnect lead. Place insulator, washer and heat sink screw loosely back into unit for later attachment of new sense lead.7. Disconnect two field coil leads from regulator and remove two regulator mounting screws.8. Lift regulator and long leads with grommet from generator housing. 9. Place new diode trio (1) and regulator base plate (2) in position as shown. Locate base plate (2) by positioning mounting hole (A) over existing mounting hole in casting.10. Temporarily install the 12.70 mm (.5 in) long mounting screw in hole (A) to hold plate. Align edges to be straight with the sides of the casting.11. Mark three new hole locations (C, D, and E), then remove diode trio and base plate from housing.12. Using a 3.6 mm (.14 in) drill bit, drill new holes (C, D, and E) in housing. Holes (C) and (E) will go through housing wall. Hole (D) is positioned in thicker cross section and will not go through. Drill hole (D) 19.1 mm (.75 in) deep, straight into housing material.13. Remove all traces of metal shavings from both inside and