Gemini Sound PMX-80 Service manual

SERVICE MANUAL

PMX-80

Stereo Preamp Mixer

CONTENT’S:

Connections & Operations:.......................................................Page 2-4

Specifications:..............................................................................Page 5

Parts Lists:.................................................................................Page 6-8

PCBs:..........................................................................................Page 7-9

Schematics:.................................................................................Page 10

Gemini Sound Products Corp.

120 Clover Place P.O. Box 6928

Edison, NJ 08818-6928

732-738-9003 (Phone) • 732-738-9006 (Fax)

Page 1

9

7 6

1

1

2

2

3

3

4

4

5

5

8 10

Page 2

19

11

12 20

13

14

21

22

15

23

24

29

30

31

32

33

17

16

34

25

26

35

27

18

36

28

Page 3

Connections

1. Make sure that the POWER (6) switch is in the OFF position. This unit
comes supplied with a 15 volt AC adaptor. Plug the male pin of the
adaptor into the rear panel POWER JACK (7). Then plug the adaptor
into a proper power source.

2. The MASTER OUTPUT (1) jacks are unbalanced and used to connect
to your main amplifier.

3. The DJ MIC (18) input (found on the front panel) accepts a 1/4"
connector and balanced and unbalanced microphones.

4. On the rear panel are 2 stereo PHONO/LINE (3, 4) inputs, 1 stereo

PHONO (5) input and 1 stereo LINE (2) input. The PHONO/LINE
SWITCHES (8, 10) enable you to set the (3, 4) inputs to Phono or Line.

The phono inputs will accept only turntables with a magnetic cartridge.
A GROUND SCREW (9) for you to ground your turntables is located on
the rear panel. The stereo line inputs will accept any line level input
such as a CD player, a cassette player, etc.

5. Headphones can be plugged into the front panel mounted PHONES

(36) jack.

Operation

1. POWER ON: Once you have made all the equipment connections to
your mixer, press the POWER (6) switch. The power will turn on and
the POWER LED (23) will glow RED.

2. CHANNEL 1: The GAIN (11), HIGH (12), MID (13), and LOW (14)
controls allow you to fully adjust the selected source. Switch # (15)
allows you to select either the PHONO 1 (5) or the PHONO 2/LINE 1
(4) input. The CHANNEL SLIDE (16) controls the output level of this
channel.

3. CHANNEL 2: The GAIN (29), HIGH (30), MID (31), and LOW (32)
controls allow you to fully adjust the selected source. Switch # (33)
allows you to select either the PHONO 3/LINE 2 (3) or the LINE 3 (2)
input. The CHANNEL SLIDE (34) controls the output level of this
channel.

4. KILLING LOW FREQUENCIES: You can use the Kill Feature on each
channel to remove Low band frequencies to create special effects
and improve your mix. Move the KILL SWITCH (17) down to remove
the low band of Channel 1 from your mix. Move the KILL SWITCH
(35) down to remove the low band of Channel 2 from your mix.

5. CROSSFADER SECTION: The CROSSFADER (27) allows the mixing of
one source into another. The left side of the CROSSFADER (27) is
CHANNEL 1 and the right side is CHANNEL 2. The CROSSFADER (27)
in your unit is removable and if the need arises can be easily replaced.
Crossfader units are available in three varieties. Part # RF-45 (which
is identical to the crossfader supplied with the mixer) has a 45 mm
travel from side to side. Part # RF-30 is available with a 30 mm travel
distance. Also available is the PSF-45 with a special curve designed
for scratch mixing. Just purchase one of these crossfader units from
your Gemini dealer and follow these instructions:

1. Unscrew the outside FADER PLATE SCREWS (B). Do not
touch the INSIDE SCREWS (C).

2. Carefully lift the fader and unplug the CABLE (D).

3. Plug the new fader into the cable and place it back in the
mixer.

4. Screw the fader to the mixer.

The CROSSFADER CURVE SWITCH (28) allows you to adjust the kind
of curve the crossfader has. When the switch is in the left position,
the curve is gradual and gentle. When the switch is in the right
position, the curve is steep and cutting (perfect for scratching). The
CROSSFADER REVERSE SWITCH (26) allows you to reverse the
crossfader so that CHANNEL 2 is controlled by the left side of the
crossfader and CHANNEL 1 is controlled by the right side of the
crossfader.

NONO

TETE

NO

TE: When the

NONO

TETE

(26) (26)

(26) is activated (moved to the right), only the crossfader

(26) (26)
reverses. The Channel Slides, Gain, Kill Switches and tonal
controls do not reverse.

6. OUTPUT CONTROL SECTION: The level of the MASTER OUTPUT (1) is
controlled by the MASTER (21) control.

7. TALKOVER SECTION: The purpose of the talkover section is to allow
the program playing to be muted so that the mic can be heard above
the music. The MIC/TALKOVER (19) switch has three settings. When
the MIC/TALKOVER (19) switch is in the left position, the mic and
talkover are both off. When the MIC/TALKOVER (19) switch is in the
center position the mic is on, the MIC INDICATOR will glow, but
talkover is off. When the MIC/TALKOVER (19) switch is in the right
position, the mic and talkover will be on and the volume of all sources
except the Mic input are lowered by 16 dB. MIC LEVEL (20) controls
the level of the MIC.

8. CUE SECTION: By connecting a set of headphones to the PHONES

(36) jack, you can monitor either channel or both together. Move the
CUE SWITCH (25) to the left to monitor CHANNEL 1. Move the CUE
SWITCH (25) to the right to monitor CHANNEL 2. Move the CUE
SWITCH (25) to the center position to split the signals from each

channel so that CHANNEL 1 will be heard in one earphone and
CHANNEL 2 will be heard in the other earphone. Use the CUE LEVEL
(22) control to adjust the headphone volume without effecting the
overall mix.

9. DISPLAY: The DISPLAY (24) indicates the MASTER output.

CRCR

CR

CRCR

OSSFOSSF

ADER REVERSE SWITADER REVERSE SWIT

OSSF

ADER REVERSE SWIT

OSSFOSSF

ADER REVERSE SWITADER REVERSE SWIT

CHCH

CH

CHCH

Specifications

INPUTS:

DJ Mic..............................................................1.5mV 600 Ohm

Phono.........................................................................3mV 47Kohm

Line.......................................................................150 mV 27Kohm

OUTPUTS:

Amp.................................................................0 dB 1V 400ohm

Max..............................20V Peak to Peak

GENERAL:

Low (Channels 1 - 2)........................................................+ 12dB/-32 dB

Mid (Channels 1 - 2).........................................................+ 12dB/-32 dB

High (Channels 1 - 2).....................................................+ 12dB/-32 dB

Gain (Channels 1 - 2)...........................................................0 to -20dB

Frequency Response....................................20Hz - 20KHz +/- 2dB

Distortion................................................................................0.02%

S/N Ratio...............................................................better than 80dB

Talkover Attenuation..............................................................-16dB

Headphone Impedance.........................................................16ohm

Power Source........................................................115V/15V AC 7.5W

230V/15V AC 7.5W

Dimensions.......................................6.5” x 14” x 3” (165 x 355 x 85 mm)

Weight........................................................................................5 lbs (2.27 kg)

Page 4

Parts Lists

Item #

1
2
3
4
5
6
7
8

9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26

Cabinet Parts and Packing

Description

PANEL CONTROL
PANEL REAR
BOTTOM COVER
BRACKET VR (SUB CHASSIS)
HOLDER FADER
KNOB SWING (LONG)
KNOB PUSH (SMALL)
KNOB SLIDE (BIG)
KNOB ROTARY (B TYPE)
INLAY KNOB (BLACK)
INLAY KNOB (GRAY)
INLAY KNOB (RED)
TRIM VR
HOLDER LED (3f 17mm)
PAD FOOT
DUST PROOF CLOTE-VR
SWING DUST PROOF CLOTH
GND SCREW
BUSHING WIRE
BAND-HEAD TAPPING SCREW/TW-E 3×6(AB)
FLAT-HEAD TAPPING SCREW 3f×6(AB)
BAND-HEAD TAPPING SCREW 3×6(AB)
FLAT-HEAD TAPPING SCREW 3f×12(AB)
BAND-HEAD TAPPING SCREW 3f×5(AB)
BAND-HEAD TAPPING SCREW (TWIN) 3f×8 (AB)
PAN-HEAD MACHINE SCREW 2.6f×4(B)

Part #

002-223
034-020
032-027
021-776
022-367
023-674
002-531
002-704
003-110
148-236
148-239
148-238
003-970
003-969
049-206
159-171
159-216
146-710
049-190
121-003A
111-043A
111-046A
111-049A
111-051A
110-172A
102-025

Printed Circuit Boards

Item #

1

PRINTED CIRCUIT BOARD PMX80-1

2

PRINTED CIRCUIT BOARD PMX80-2

3

PRINTED CIRCUIT BOARD PMX80-3

Description Part #

262-073
262-074
262-075

Page 5

Parts Lists - PCB1 Input Output

Item #

Item #

Designators

1

IC1, IC2, IC3

2

IC5

3

IC4

Designators Description Part #

D3, D4

1

D1, D2

2

SW3

3

J4

4

J1

5

J2

6

ICs

Description Part #

INTEGRATED CIRCUIT NJM2068LD
INTEGRATED CIRCUIT NJM7912FA
INTEGRATED CIRCUIT NJM7812FA

Electrical Parts

RECTIFIER DIODE 1N4002 (1N4003,1N4004)
ZENER DIODE 1/2W 12V
SLIDE SWITCH
DC JACK 2.5
4P RCA JACK
6P RCA JACK

074-145
074-114
074-107

079-027
079-012
081-038
092-135
161-105
161-106

Parts Lists - PCB2 Main

Item #

1
2
3

4

Item #

1
2
3
4
5
6

ICs

Designators

IC4
IC10
IC1-2, IC6,
IC8, IC9
IC3, IC7

INTEGRATED CIRCUIT NJM2068LD
INTEGRATED CIRCUIT NJM4556AD
INTEGRATED CIRCUIT NJM4558LD

INTEGRATED CIRCUIT OR LB1423N

Description Part #

074-145
074-100
074-104

074-154

Electrical Parts

Designators Description Part #

D9-12
SW4
SW2, SW5, SW7
VR3, VR9
VR8
VR6

LIGHT EMITTING DIODE (GREEN) 3.15f
SLIDE SWITCH
LEVER SWITCH 4P2C
ROTARY VR 16f L=20 GAIN 10KA×2
ROTARY VR 16f L=20 MIC 50KA
ROTARY VR 16f L=20 MASTER, 500KA×2

080-104
081-038
082-019
071-161
071-066
071-158

Page 6

Schematic

R69

47

R45

47

+VCC

-15 -9 -3 0 +3 -15 -9 -3 0 +3

D12

LED

D11

LED

D10

LED

D9

LED

D8

LED

D1

LED

D2

LED

D3

LED

D4

LED

D5

LED

MIC OFF

RED RED

GREEN

GREEN

GREEN

RED RED

GREEN

GREEN

GREEN

MIC ON

TALKOVER

+VCC

-VCC

MASTER

J2C

X4

X2

R41

430

R44

47K

R68

47K

C33

10/16

R74

IC7

LB1403N

9

C52

6

8

4

5

3

7

2

1

9

6

8

4

5

3

7

2

1

IC3

LB1403N

SW3D

VR8

50KA

C35

R26

1K5

C21

154

R14

R27

33K

VR4A

50KEx2

C17

154

R34

3K6

R31

1K5

30K

R50

30K

0.47/16

R78

4K3

-VCC

R75

10K

C53

10/16

C30

0.47/16

R38

4K3

R42

10K

C29

10/16

R76

300K

R72

300K

C50

10/16

1

IC4A

2068LD

4 8

IC3-4

IC3-8

2

3

C40

22P

C46

10/16

R55

3K3

7

IC4B

2068LD

68P

6

5

C41

68P

R48

30K1 1%

R56

30K1 1%

R40

1K 1%

R47

1K 1%

C16

22/16

C7

22/16

123

MIC

J1

C1

10/16

1

IC1A

4558LD

C22

56P

4 8

IC7-8

IC7-4

2

3

C20

682

C3

562

4K7

R25

24K

R12

8K2

R8

5K6

R11

33K

C14

103

VR1A

VR2A

50KEx2

50KEx2

R23

2K4

R24

33K

C26

10/16

1

IC2A

4558LD

4 8

R19

5K6

IC5-8

C8

IC5-4

181

2

3

R9

R4

2K

C23

10/16

VR5A

VR3A

10KAx2

1

C44

IC6A

VR6A

SW3C

R18

1K5

VR4B

R32

3K6

R33

1K5

100K

50KA

R21

1K

4558LD

500KA

4 8

IC2-4

IC2-8

2

3

VR6B

C38

6.8P

SW3A

R59

4K3

D6

+VCC -VCC

CURVE

SW1A

C19

C25

154

R17

4K7

R30

33K

50KEx2

C27

154

VR1B

R28

500KA

C31

10/16

SW3B

R73

390K

LED

R39

75K

R37

75K

R53

75K

SW6A

R61

75K

R58

4K3

R79

4K3

SW1B

182

182

C18

R51

20K

R62

20K

C6

10/16

7

IC1B

4558LD

C4

56P

6

5

C12

682

C11

562

R16

24K

R13

8K2

R7

5K6

R20

33K

C15

103

VR2B

50KEx2

50KEx2

2K4

R29

33K

C28

10/16

7

IC2B

4558LD

R15

5K6

C9

181

6

5

R1

2K

C24

10/16

VR5B

GAIN CH-1

VR3B

10KAx2

R22

C32

R10

50KA

1K

R66

430

C48

7

6.8P

6

5

10/16

R77

390K

SW6B

100K

-VCC

10/16

IC6B

4558LD

NORM/REV

R82

1K5

R86

VR10A

50KEx2

R94

3K6

R83

1K5

R57

1K

X-FADER

X-F

C57

33K

C54

D7

LED

POWER

65432

R

X3

SW5A SW5B SW5C SW5D

1 -2 \ 2 -1

C61

56P

IC8-8

154

C68

562

R85

4K7

R104

5K6

R103

33K

154

VR12A

VR13A

50KEx2

50KEx2

R90

2K4

C59

181

R95

5K6

IC6-8

R87

2K

IC4

1

L

SW6C

SW8B

C67

C79

10/16

1

IC8A

4558LD

R101

4 8

IC8-4

2

3

C62

682

R93

24K

VR10B

R108

8K2

C70

103

R92

R84

R107

33K

C56

10/16

1

IC9A

4558LD

4 8
IC6-4

2

3

R110

100K

C77

10/16

VR11A

50KA

1K

VR9A

10KAx2

R97

X4X3

C15

22/16

22/16

22/16

Z 12VD1Z 12V

1

2

J4

-VCC

R125

7

4558LD

5

R105

8K2

C69

R106

33K

C55

7

IC9B

6

5

C73

VR11B

20K

10/16

C71

R109

103

10/16

4558LD

C45

100/16

R113

R3

R115

R6

R65

R70

682

24K

10/16

10KAx2

10

C65

IC8-4

10

C13

IC7-4

10

C78

IC6-4

10

C2

IC5-4

10

C43

IC3-4

10

C51

IC2-4

CUE LEVEL

R111

100K

50KA

R98

1K

22/16

R19

10

-3

C34

22/16

R37

10

-VCC

-2

C10

22/16

R10

10

-1

C46

1/50

3

Vout

GND

1

Vin

IC5

7912

2

C47

1000/25

SW3A

R47

750

D4

1N4002

22/16

22/16

22/16

22/16

22/16

22/16

+VCC

R122

10

C82

220/16

C80

22P

R118

20K

+VCC

R67

10

C49

22/16

IC5A

C36

22P

2

VR7A

50KA

C39

SW4C

R46

43K

-VCC

R123

R120

47

1

4556

IC10A

4 8

2

3

-VCC

R116

2K

1

R54

4558

C34

4 8

3

47/16

CH1

SW4A SW4B

R52

43K

CUE

J2

123

R121

47

10

220/16

7

C83

IC10B

4556

C81

22P

R119

20K

6

5

R117

2K

7

10

22/16

IC5B

4558

C45

22P

50KA

6

5

VR7B

C42

47/16

CH2

SPL

SW4D

R60

43K

R63

SW4

43K

R27

10

+VCC

7812

C22

+3

R30

10

C27

+2

R2

10

C3

+1

C43

1/50

3

Vout

GND

2

Vin

1

C44

1000/25

C48

100/16

POWER

D2

R48

750

SW3B

D3

1N4002

AC15V-JACK

+VCC

R114

10

C72

22/16

IC8-8

R2

10

C5

22/16

IC7-8

R102

10

C64

22/16

IC6-8

R5

10

C10

22/16

IC5-8

R49

10

C37

22/16

IC3-8

R71

10

C47

22/16

IC2-8

R36

75K

R35

75K

R43

75K

R64

75K

SW6D

R81

4K3

R80

4K3

SW8A

C66

182

182

R124

20K

1K5

R89

50KEx2

3K6

1K5

C76

IC8B

C75

56P

6

C58

154

C74

562

R112

4K7

33K

R99

5K6

R100

33K

C63

154

VR12B

VR13B

50KEx2

50KEx2

R91

2K4

R96

5K6

C60

181

R88

2K

GAIN CH-2

VR9B

MAIN PCB

IN/OUT PCB

R13

R9

R12

C5

SW2A

PH1;PH2\LN1

C12

10/16

R14

1K

1

C11

273

IC1A

2068LD

100K

4 8

+1

-1

2

3

C9

822

8K2

C8

56

R8

1K

R11

47K

180

47/16

J1A

PH1

SW2B

SW2C

X1

X1

C7

R3
7

IC1B 2068LD

5

C4

56

R4

R7

47K

SW2D

10/16

1K

C2

6

C6

1K

R1

C1

47/16

C19

10/16

C13

10/16

R25

1K

R15

7

C23

273

273

R5

100K

R26

100K

6

822

180

5

C18

822

R6

8K2

R24

8K2

R23

R28

180

C24

47/16

1K

1

IC2A

2068LD

+3

-3

IC2B

2068LD

48

2

3

C21

56

C16

56

1K

R20

1K

R22

47K

R16

47K

C20

47/16

J1B

PH2/L2

PH2/L2

SW1A

SW1B

SW7A

LN3;PH3\LN2

C36

C14

273

R18

100K

R41

100K

C17

822

C33

R21

8K2

R40

8K2

180

R39

R17

180

C29

47/16

SW2A

PH3/L2

SW7B

SW7C

X5

X2

C35

10/16

R42

1K

1

273

2068LD

IC3A

+2

2

3

822

R36

SW2B

SW7D

C30

10/16

R31

1K

C37

10/16

C40

7

C26

4 8

-2
IC3B 2068LD

6

5

C31

C32

56

C28

56

1K

1K

R32

R38

47K

R34

47K

C25

47/16

J2A

PH3/L2

10/16

273

R33

100K

C38

101

C39

101

822

R35

8K2

R29

180

R431KR44

1K

J2B

L3

Page 8