Repair Guide; Precautions In Disassembly And Reassembly - Hitachi DN 12DY Technical Data And Service Manual

10. REPAIR GUIDE

Be sure to remove the storage batteries from the main body before servicing. Inadvertent triggering of the switch
with the storage battery connected will result in a danger of accidental turning of the motor.

10-1. Precautions in Disassembly and Reassembly

The [Bold] numbers in the description below correspond to the item numbers in the Parts List and exploded
assembly diagram for the Model DN 12DY.
10-1-1. Disassembly
(1) Remove the Hook [19].
Place your fingers inside the Hook [19], and expand it outward enough so that it can be removed from the
main body.
(2) Disassembly of Housing (B):
Remove the seven Tapping Screws (W/Flange) D3 x 16 [13] which fix the main body. Then grasp the lower
portions of Housing (A) and Housing (B) where the battery is inserted, and gently separate them.
(3) Disassembly of the Motor, Switch:
When Housing (B) has been removed, the Motor [8], DC-Speed Control Switch [16] can be taken out together
in a single assembled unit. These assembled components can be disassembled as follows: With a soldering
iron, disconnect Internal Wires (A) [9] [10] of the Motor [8].
Remove the single Bind Screw M3 x 7 [5], and disassemble the Fin [6] from the FET (Field Effect Transistor)
of the DC-Speed Control Switch [16].
[Note] Do not disconnect the three FET internal wires that are soldered to the DC-Speed Control Switch [16].
(4) Removal of the Drill Chuck 10TLRJ-N:
The Drill Chuck 10TLRJ-N (W/O Chuck Wrench) [3] can be removed from the Spindle [2] as follows:
(a) Fully open the jaws of the Drill Chuck 10TLRJ-N (W/O Chuck Wrench) [3].
(b) Fit a J-217 spindle lock jig (special repair tool, Code No. 970998) onto the flat surfaces provided on the
Spindle [2], secure it in a vise, and remove the Flat Hd. Screw (Left Hand) M5 x 17 [4] by turning it
clockwise (to the right) with a straight edge screwdriver.
(c) Turn the hexagonal portion at the tip of the Drill Chuck 10TLRJ-N (W/O Chuck Wrench) [3]
counterclockwise with a 16 mm socket wrench to remove the Drill Chuck 10TLRJ-N (W/O Chuck Wrench)
[3] as shown in Fig. 3. If it is difficult to loosen, use a pipe extension or similar tool.
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