Hafler DH-500 Instructions For Assembly And Operation Manual Download

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DH-502

INSTALLATION INSTRUCTIONS

Disconnect AC power from the DH-500 and remove all connect-
ing cables.

Remove the 17 screws which secure the cover along the top front,
sides and rear. Set cover aside. DO NOT GRAB THE AMPLI-
FIER PANEL OR HANDLES WHEN THE

COVER IS RE-

MOVED. You might bend the chassis.

Turn the amplifier over, or stand it on the nansformer end.

Loosen, but do not remove the two front screws which secure the
amplifier module near the front (center) of the chassis. Remove
the two screws at the rear which secure the module. Return the
amplifier t o its upright position.

Prepare one each red and green wires each 16” long. Twist them
together throughout their length.

Select the PC-7A circuit board. Note

that

the eyelets arcnumbered

on the circuit side of the board, with eyelet #l to the left when the

row of eyelets

is nearest you, and the board is upside down to

make soldering easier. Connect the wires from the components
side of

he board,

and be sure each is securely soldered to the

circuitry.

Connect the red wire of the twisted pair to eyelet # 1 of PC-7A. (S)
Connect the green wire to eyelet #3. (S)

Prepare a 3-l/2” green wire and a 4” red wire. With one pair of
ends even, twist these together. At the

uneven

ends, connect the

green wire to cyelet #4 of PC-7A. (S). Place the pair off toward
eyelet #l, and connect the red wire to eyelet #6. (S)

Prepare a 5” red wire and a 6” green wire. Twist these together
with one pair of ends even. At the

even

ends connect the red wire

to eyelet #2. (S) Connect the green wire to eyelet #5. (S)

Unsolder the twistcd pair of leads from eyelets 1 and2 of the right

amplifier module at the center rear of the amplifier. This pair of
leads which

connects to the

right input socket, will no longer be

used while the amplifier is funtioning monophonically. These
leads must be

taped

securely so that there is no possibility for the

bare wire to contact any portion of the circuit. Masking tape is
sufficient, but electrical tape is preferred. These leads may be

removed

if desired.

COMPONENT SIDE

0 6

0 5

0 4

0 2

R15

0 3

10. Remove the rear rop screw securing the right channel amplifier

circuit board to the hear sink just above where the twisted pair was
disconnected. Do nor lose the fiber spacing washer which is
between the circuit board and the heat sink. This washer is not
used on later production DH-500s.

Select one of the screws from

the bridging kit, and the mounting bracket. The bracket is
anchored at this location, flat surface up, with the screw inserted
fust through the single tab from inside the bracket. then through
the circuit board. the fiber spacing washer, (optional) and into the
heat sink.

11. Select the two screws and nuts and the circuit board PC-7A. With

the components facing out, secure the board t o the outer surface
of the bracket tabs.

Select the short twisted pair of wires connected to eyelets 4 and

6. Connect the red wire to the upper eyelet #l of the right circuit
board at the center rear. (S) Connect the green wire t o the lower
eyelet #2. (S)

13. Place t h e long pair of wires from eyelets 1 and 3 down between

the amplifier module mounting bracket and the back of the
chassis. The module can be tilted forward t o facilitate this.

Connect the

red wire t o the lower ey elet #l on the left circuit

board. (S) The easiest way is to wrap it in a tight loop around t h e
bare stub of the wire presently connected to this eyelet. Be sure
both wires are soldered securely to he board. Connect the green
wire t o the upper eyelet #2 in the same fashion. (S)

Making sure that no wires are trapped by the mounting bracket,

reinstall the. two screws securing the rear of the module to the
chassis. Tighten all 4 screws.

Connect the red wire of the remaining twisted pair from PC-7A

to eyelet #6 of the PC-9 circuit board behind the power trans-
former, (S)This wire may be connecred t o the stub of the existing
wire as before. Connect the green wire to eyelet #4 of PC-9. (S)

Eyelei #I of PC-9 is nearest the edge of the chassis.

16.0 Reinstall the amplifier cover.

Rl
R2
R3
R4
R5

R6
R7
R8
R9
RlO
Rll
R12
R13
R14
R15

R16
R17

PC-7A PARTS

22.1K, l%, metal film
2.2K. 1/4w,  5% carbon film
2.2K, 1/4w, 5% carbon film
47 ohms, 1/4w.  5% carbon film
47 ohms, 1/4w.  5% carbon film

8.2K, 1/4w, 5%, carbon film
8.2K, 1/4w, 5 % , carbon film

47 ohms, 1/4w, 5% carbon film
47 ohms, 1/4w, 5% carbon film

2.2K, 1/4w,  5% carbon film
2.2K, 1/4w, 5%  carbon film
22.1K,  l%, metal  film

IO0 ohms, 1/4w, 5% carbon film
100 ohms, 1/4w, 5% carbon film

47 ohms, 1/4w,