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PASS LABORATORIES ALEPH ONO SERVICE MANUAL REV 0, 1, 2, 3 9/30/1997
Product Description The Aleph Ono starts off with a low noise power supply using a custom designed, shielded, low noise 60 Watt toroid transformer. This gives plus and minus 42-volt DC primary supplies. These are passively filtered with resistors and capacitors. The rails are then actively regulated down to plus and minus 32 volts with zero feedback Mosfets, Q9 for the positive rail and Q23 for the negative. The Mosfets references are filtered zener stacks of four 9.1 volt zeners. These supplies are then passively filtered again for each channel. The moving coil stage has it's own separate capacitance multiplier Q24 that regulates down to 26 Volts for Q14 the MC amp cascode. The moving coil stage uses 4 matched very low noise Jfets (Q 10 - Q13) operated in parallel giving a noise floor of 475 picovolts. These are operated at about 15 volts on the drain. These devices operate feedback free and feed a cascode stage (Q14) whose output is buffered by Q15 unity gain inverter. This signal is then feed to the main gain and equalization stage. The main gain stage provides its gain with a dual monolithic JFET (Q5) biased with a low noise current source (Q16). This differential pair is cascoded into Q1 and Q2 and feeds a P channel Mosfet and then Transistor Q6 . Q3 and Q6 are feed to current source Q17. The reference for Q17 and Q18 is red Led D5 witch sets the voltage across R53 and R67 at 1 volt after the base emitter drops. This reading across these two resistors is important for this stage to work properly. The equalization is performed using 1-% tolerance metal film resistors and polypropylene capacitors. C4, C5 and C6 along with R8 and R9 provide the Riaa equalization curve in the feedback loop. R28 and C8 provide the high frequency EQ and roll off. Balanced negative out is provided by a unity gain inverter. Q21 and Q22 differential pair feed Q8 and Q19 N channel Mosfets.
Q25 and Q26 are used to power the mute relays. The front panel LED must function for Q25 to turn on and pull the mute relays off. The differences between revisions are generally minor in nature. In rev 1 muting relays were added to the output. More gain settings were added in rev 2, along with a physical layout change. An extra loading resistor was added to the moving magnet input in rev 3.
ALEPH ONO SPECIFICATIONS
Gain 40 dB @ 1 KHz (MM) 71 dB @ 1 KHz (MC) 76 dB @ 1 KHz (MC) RIAA response Distortion plus/minus .1 dB 20-20 KHz < .05 % THD @ 20 volts balanced @ 1 KHz Maximum Output Output Impedance Input Impedance 20 volts rms. 150/150 ohms 47 Kohm 0-650 pF (MM) 5 ohm - 47 Kohm (MC) Unweighted Noise -90 dB ref. 10 mV input (MM) -81 dB ref. 1 mV input (MC) Power consumption Dimensions Weight 20 watts 19 " W x 11.5 " D x 4 " H 35 lbs.
PASS
Pass Laboratories PO Box 219 24449 Foresthill Rd. Foresthill CA 95631 tel fax web site: (916) 367 3690 (916) 367 2193
www.passlabs.com
A
B
C
D
E
F
G
H
1
30 Volt regulator
R44
+ 40 Volts
1
Q9
R30
5.1
610
221
2.2K
R29 C21 1KUF R2 5.1
C23
C24
+
D1
1KUF
1KUF
D2
D1
1N4004 * 4
C7
10UF
C22 1KUF
D2
D3
9.1V
.25 AMP SLOW 240 AC .5 AMP SLOW 120 AC
D4
D3
D4
C31 1KUF
C32
-
T1
S1
P1
F1
1KUF
30 VAC
VAL
S2
P2
R71 5.1
- 40 Volts
4007
S1
P1
- 30 Volt regulator
Q23
2
R75 1.5K 1KUF C12
9610
+ 30 VOLTS
R72 221
R73 2.2K
30 VAC
ACJACK
S2
P2
- 30 VOLTS
2
CL60 R6 10K Q3 9610 R12 221 V+ Q6 2SA991 C3 100PF R26 Q7
MC SUB REGULATOR
Q24 ZTX450 C34 3300UF R76 10K C10
A
C29 1KUF
C30 1KUF
C33
D9
TH1
10UF
D8
26 VOLTS
CB3 .047
R51 4.75K
R42 3.3K
R4 4.02K
D7
D6 9.1V
TO MM STAGE
R3 2SC1844 8.2K Q1 2SC1844 Q2
GAIN SELECT SHORT FOR -4 dB
D
C19 220UF 10UF R80
G
Q15 R17 10K 2SK170
S
R66 499 4.02k 1K R49 100K R50 56 S1:1 R1
1 4 9 1 3 1 2 1 1 1 0 G 1 6 1 5 D
R41 R81
1K
R23 22K
610 C11 10PF 221
C16
3
R18 10K
+
C35 3300UF R40 499 C37 R16 Q14 2SC1844
1 2 3 4 5 6 7 8 A
330PF
MOVING MAGNET J1 INPUT
Q5 2SK389
ADJUST R25P FOR
C4 .01UF
D G
C6 .033UF R25P 2.21K R7 R21 100 100 R25 5K R28 33 R8 7.32K R9 88.7K
.35 VOLTS
R28 150
S S
GAIN CB4 SHORT .047 FOR - 10 dB
221 R20 47K
3
C7 10UF C41 220UF C1
+ + +OUT
R82
150 R27 33 220UF C2 .047UF C5 .0027 R14 100K 9610 R52 R5 6.8K 221 Q16 2SC1844 R22 221 R55 221 R67 R54 221 Q17 2SC1844 Q18 C8 .01
220UF
10K
C13
C14 C15 220 330
CX RX
R79 1K
MM
MC
15 VOLTS
MOVING COIL INPUT
J2
G G G G
100
Q10
D
Q11
D
Q12
D
Q13
D
C29 100PF
2SK170 R31 47K R45 R48 22 22 22 22 R46 R47
S
2SK170
S
2SK170
S
2SK170
S
1 VOLT
475
C27 220UF
D5 RED
C28 4.7UF
R53 150
1 VOLT
-30 VOLTS
4
S2:2 R39 R38 24R9 R37 47R5 R36 100
6 5 8 7 6 5 4 3 2 1 4 3 7 2
BALANCED OUT
C20 R70 5.1 1KUF
4
RCA OUT
R57 221 R61 Q20 9110 C39 Q21 9110 .001 R61 221 R68 4.75K R62 22K R63 C38
+OUT
NC1
K1:B
J3
C1
2
+
J4
NO1
MUTE
10
8
1
VAL
1
MOVING COIL PREAMP + 30 dB
R56 9.1V R11 4.75K R12 221 Q8 610
G
XLRO
RELAY
3
-
NC2
K1:C
C2
NO2
VAL
R35 R34 R33 R32 1K 825
249 475
Q4 ZTX450
R24 221
R65 47 R13 332 C9 10UF R15
-OUT
RIGHT CHANNEL SHOWN
R69 221 Q21 9110
221
22K 10UF R60 221 R59 475
Q19 610
100K
C? 680PF
Installed rev 3 boards starting sn 8029 UNREG 40V 1.5K
R78
5
3.32K R64 47 D?
Q25
LEFT CHANNEL DESIGNATORS USE REFERENCE DESIGNATOR FOLLOWED BY LETTER A
9610
5
R74
D11
K1:A
+
+
-
-
D10
C39 .01PP ECO 10-8-97 ALEPH ONO
FILE NAME PL41R3.S01
Q26
UNREG 40V
R77
610
+
750K
C40
PL41R3
DRAWN BY WAYNE COLBURN
220UF
6
Title
6
Size
Number
Rev
D
Date
Drawn by
Filename
Sheet
of
A
B
C
D
E
F
G
H