Hafler DH-500 - Manual (Page 20)

DH-502 INSTALLATION INSTRUCTIONS
1.
2.
3.
4.
5.
6.
7.
8.
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
A
A
0 4 0 2
i
R15
A
1
0 3 01
6
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, 5% carbon film
3.3K, lw, 5% metal film
3.3K, lw, 5%. metal film
RMP/4-2212
RC/4-222
RC/4 -222
RC/4-470
RC/4-470
RC/2-822
RC/2-822
RC/4-770
RC/4-770
RC/4-222
RC/4-222
RMP/4-2212
RC/4-101
RC/4-101
RC/4-770
RM l-332
RMl-332
Cl 1 OmF, 16V. non-polarized CERNP-106
c 2 6.8pF. 1 00V, dipped mica CM -068
c3 22mF. 25V, electrolyte CER-226AA
c4 22mF. 25V, electrolyte CER-226AA
Ql BC55OC NPN nansistor SSH-650
Q2 BC55OC NPN transistor SSH-650
Q3 BC56OC PNP transistor SSH-65 1
Q4 BC56OC PNP transistor SSH-65 1
Q5 MPSA63 PNP transistor SSH-695
Q6 MPSA13 NPN transistor SSH-645
LIST PC-7A PARTS LIST