Luxman SQ 505 X Service Manual

Page 2

CIRCUIT DESCRIPTION

POWER SUPPLY

The power supply consists of two parts designed for supply
of power to the main amplifier and the preamplifier
respectively. For the main amplifier driven by a high
current load, silicon diode D602 (582) is used and supply

voltage values are +42V and -42V.

Power sources other than for the power amplifier are
obtainable by D601 (SRIK\4) with the half wave rectifi-
cation circuit and ripple filter. Supply voltage values at
each section are: equalizer stage 43V, tone control and
intermediate stages ~26V.

PREAMPLIFIER

The preamplifier consists of an equalizer, an intermediate
amplifier and a tone control. The amplifier is so designed
that the preamplifier section can be isolated from the
power amplifier section if exclusive use of the preamplifier
is desired. Preamplifier output signals can be taken out
from the PRE OUT terminals. The equalizer adopts the
NF circuitry using 3 silicon transistors, 25A493 (0201,
0203) 25C1000 (0202) per channel and is designed to
provide proper equalization on the input signals. Major
components to constitute the equalizer are integrated in
the printed circuit board P8908. Input signals given
through the AUX-1, ~2, and -3 terminals bypass the
equalizer and are fed directly to the later stages of this
amplifier.

Controls arranged after the equalizer are: REC OUT
CONNECTOR, TAPE-MONITOR SWITCH, MODE SE-
LECTOR, BALANCE CONTROL and VOLUME CON-
TROL. The intermediate amplifier consisting of 0301 and
0302 is a flat amplifier adopting 2-stage NF circuitry which
is designed to boost the equalizer or AUX. This covers the
insertion loss sufficiently by the tone control in the next
stage and leads low impedance output to the tone control
for its smooth function. The tone control adopts the
CB-NF-circuits of transistors, 0401 0402. Any desired
frequency response can be adjusted by the following con-
trols: variable resistor VR401, rotary switch S401 (BASS),
and variable resistor VR402, rotary switch S402 (TR EBLE).
Major components of the intermediate amplifier are arrang-
ed on the printed circuit board P3908 and the tone control
circuits are integrated in the printed board P3909.

MAIN AMPLIFIER

The main amplifier adopts direct coupling 2-stage differ-
ential driving and pure-complementary circuitry composed
by the heat sink with high output power transistors 0107
25D 188 (NPN), 0108 28A627 (PNP) (2 transistors per
channel), 2 printed circuit boards (one each for both chan-

nels) with several components designed to drive the power
transistor and so on.

0107 and 0108 are independently fixed to the heat sink,
which is fixed to the rear panel together with PB910, and
coupled with P8908 through 6P lead sockets. The printed
circuit boards P3910 consist of the lst stage differential
amplifiers 0101, 0102, 2nd stage differential amplifiers
0103, 0104, the driver transistors 0105, 0106 and other
CR components connected with the power transistors for
easy replacement or repair of the block.

SPECIFICATIONS

I MAIN AMPLIFIER
HMS POWER

THD

INTER MODULATION
DISTORTION

POWER BANDWIDTH

FREQUENCV
RESPONSE

INPUT CONNECTOR

DAMPING FACTOR

RESIDUAL NOISE

I PRE AMPLIFIER

FREQUENCY
RESPONSE

THD

INPUT SENSITIVITY

INPUT IMPEDANCE

S/N HAI l0

PERMISSIBLE INPUT
VOLTAGE (Mam)
TONE CONTROL

FILTER

BASS BOOST:
IOTHERS
TRANSISTORS, ETC.

ANNEXED CONTROLS

POWER CONSUMPTION
DIMENSIONS

WEIGHT

30/30 watts (80 both channels driven)
35/35 watts (80 one channel driven)
less than 0.04% (8&1, 30W)
less than 0.04% (89, 30w)

5H2 »- 50,000Hz, ~3dB, 0.04%
10Hz ~» 60,000Hz, less than -1dB

SENSITIVITV: 430mv,
IMPEDANCE: 50K§L
30(801. 60(159)

less than 1mv
10 - 50,000Hz, fidB (auxV1)

less than 0.05% (aux-x1, 1KHZ, 1v)
phonoii, phonoizt 2mv

aux-1, aux~2, aux73: 80mv
phono~11 30K/50K/100KK), (selectable)
phone-2: SOKQ

aux41, auxAZ, aux73: 30KB
phon071, phonoA2: better than 63dB
aUXrI, aux-2, aux73: better than 80dB

phono. 300nm, aux indefinite

LUX TYPE NF
selection

Bass: defeat, 150, 300, GOOHz
Treble: defeat, 6K, 3K, 1.5KHZ
Bass cut: 7OH2 iifidB/oct.)
Treble cut: 6KH2 l'GdB/octJ
100Hz (6d8/cct.)

turnover frequency

,1

SILICON TRANSISTORS (31), DIODES
I2) VARISTERS (4)

Attenuator (-18dB), speakers switch
(main/remote)

Tape monitor (2 sets), pre/main amp
separator, headphone jack, etc,

130 watts (maximum output, 80, both
channels driven)

160mm I6-5/16)H, 450mm I17»3/4")W,
268mm i109/16")D

10 kgs (22 Lbs)