Hafler DH-110 User Manual

Page 9

BUILDING THE KIT

Partial mechanical assembly of the kit provides protec-

tion for major components during shipment. Most of the

hardware thus used is included in the quantities listed in
the parts list. The exception is that used to install the rear
mounting bracket on the PC-14, as this is considered an in-
tegral assembly. Only the two screws securing the bracket
to the side pieces need be removed, along with the
hardware securing the front sub-panel. Dismount the
power transformer and remove the side pieces.

A “set” of hardware includes a screw and a KEP nut

with attached lockwasher. Always install the lockwasher

side first. Screws are always inserted from the outside of

the chassis unless otherwise specified. #4 hardware is
smaller in diameter than #6. To separate #4 nuts from the

#6s, use a long #4 screw to test.

We suggest you check off the parts as you unpack the

kit, and separate them in an egg carton for convenience.

1 The flanges of the front sub-panel bend towards the

inside of the preamp. Select the U-shaped head-

phone jack mounting bracket and 2 sets of #4
hardware. Install the mounting bracket on the out-

side of the front panel, in front of the rectangular

hole in the lower right comer.

Select the headphone jack, its washer and nut.

Install it through the front panel with the single lug at
the bottom. The washer goes outside the bracket,

secured by the nut.

Prepare a 2” black wire. Connect one end to the

lower forward lug of the headphone jack. (S). Place
this wire through the panel.

Prepare a 14½” green wire, but strip 3/8” of insulation

from one end. Prepare a 14½” red wire. Prepare a 14½”
black wire. Start with the red wire ¼ ” longer than the
longer bare end of the green wire, and the black wire ½”
shorter than the green wire. Twist these 3 wires together
uniformly throughout their length. Make about 3 com-
plete twists every two inches. On the rear of the phone

jack 8 numbered positions identify the 6 lugs in a counter-
clockwise rotation, with the #2 lug at the bottom (in line

with the front lug), and the #6 lug at the top. Insert the

longer bared end of the green wire through the #8 lug and

connect it to lug #7. Solder both lugs. Connect the red

wire to lug #6. (S).

5 Prepare another 14%” green wire with

3/8”

stripped from

one end. Prepare one end of a 14½” black wire. Do not

strip the other end. Prepare another 14½” red wire. Start
with the longer green wire end ¼” longer than the red

wire, and the bare end of the black wire ½” shorter than
the red wire.

Twist these together as before. Insert the

longer end of the green wire through lug #3 of the phone

jack and connect it to lug #4. Solder both lugs. Connect

the red wire to lug #2. (S).

Select the power switch and two #4 screws. Install

the switch above the headphone jack so that the
body of the switch is offset to the outer edge of the

panel.

Select the main PC-14 circuit board assembly, with

the fuse in place, and the rear bracket installed, and

a rubber grommet in the bracket. Select the 6 larger
nuts and washers for securing the controls to the
front sub-panel. The two largest sets are used for the
selector switches; the volume control is the smallest
size, next to the power switch; the 3 other sets go on
the 3 central control shafts. Be sure all the locating
lugs on the controls engage the holes in the panel be-
fore securing the hardware. The wires from the
phone jack go under the board. Push the ends of the
wires through the grommet.

Select the small circuit board assembly PC-13 and

two #4 screws. With the circuit board uppermost,
position the assembly at the top of the large front
panel opening so that the sockets on the board align
with the pins from below, and plug the board down-
ward onto the pins. Make sure each pin is properly
engaged. Secure the assembly with screws through
the panel.

Set the front panel aside, and select the PC-12 circuit board.

The front of the board marks the component locations, and “J”
designations. Most components mount on

the front.

Always

install them tight against the board, and solder each lead on the

back

(circuit) side. Then cut off all excess leads.

Select the two 22,100 ohm resistors (red, red,

brown, red) and install them at locations R50 and
R150.

Select the two 1,100 ohm resistors (brown, brown,

black, brown) and install them at R21 and R121.

Install the four 1 megohm resistors (brown, black,

black, yellow) at locations R22, R23, R122 and
R123.

Select the two 4-pin molded sockets. These are to be

installed at locations J26 and 5126 on the front of the
board, with the pins through the upper row of holes
(arrow) at each location. The lower row of holes
provides access from the rear of the board for plug-in
capacitors. lb assure correct alignment of the sock-
et, insert a capacitor lead from the rear into holes E,
F, G and H to engage the sockets while you solder
the pins, and then remove the capacitors. Be sure

solder flows freely around each mounting pin for a

good connection. Sometimes these pins do not ac-
cept solder easily.

The proper way to install the 24 phono input sockets

is to first insert a phono plug (on the end of one of the
audio connecting cables supplied in the kit) so that
the center contact will not be deformed in the
mounting process. Adjacent to the center hole for