Gemini Sound BPM-1000 Service manual

SERVICE MANUAL

BPM-1000

Stereo Preamp Mixer

CONTENT’S:

Connections & Operations:.......................................................Page 2-5

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

Parts Lists:.................................................................................Page 5-7

PCBs:........................................................................................Page 8-12

Schematics.............................................................................Page 13-14

Gemini Sound Products Corp.

120 Clover Place P.O. Box 6928

Edison, NJ 08818-6928

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

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LIFT

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Connections

1. Before plugging in the power cord, make sure that the VOLTAGE SELECTOR
(43) switch is set to the correct voltage.

NONO

TETE

NO

TE: This product is double insulated and not intended to be

NONO

TETE

grounded.

2. Make sure that the POWER (1) switch is in the off position. The POWER LED (2)
will be off.

3. The BPM-1000 is supplied with 2 sets of amp output jacks. The BALANCED
OUTPUT AMP (56) jacks are used to connect to your main amplifier using
standard XLR cables. We recommend using the balanced amp outputs if the
cables to your amp are 25 feet or more. Balanced outputs have three separate
conductors, two of which are signal (positive and negative) and one shield
(ground). Pin 1 is ground (shield). Pin 2 is signal hot (positive). Pin 3 is signal
cold (negative). The OUTPUT AMP (44) jacks are unbalanced and used to
connect to your main amplifier. The OUTPUT BOOTH (45) jacks allow you to
hook up an additional amplifier.

4. The MIC 1 (3) input (found on the front panel) accepts a 1/4" or XLR connector.
The MIC 2 (58) input and the MIC 3 (57) input (found on the rear panel) accept
1/4" connectors. All accept balanced and unbalanced microphones.

5. On the rear panel are 1 stereo PHONO/LINE (53) input, 2 stereo PHONO (49,

51) inputs, and 5 stereo LINE (46, 47, 48, 50, 52) inputs. The PHONO/LINE
SWITCH (55) enables you to set the (53) input to Phono or Line. The phono
inputs will accept only turntables with a magnetic cartridge. A GROUND SCREW
(54) 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.

6. Headphones can be plugged into the front panel mounted HEADPHONE (13)
jack.

SUGGESTION: You can use the Cut Features on each channel to remove Low,
Mid and/or High to create special effects.

6. CROSSFADER SECTION: The CROSSFADER (27) allows the mixing of one
source into another. The BPM-1000 features an assignable crossfader. The
ASSIGN (28, 31) switches allow you to select which channel will play through
each side of the crossfader. The ASSIGN (28) switch has 4 settings (1, 2, 3 or 4)
and allows you to select channel 1, 2, 3 or 4 to play through the left side of the
crossfader. The ASSIGN (31) switch has 4 settings (1, 2, 3 or 4) and allows you to
select channel 1, 2, 3 or 4 to play through the right side of the crossfader. There
are two OFF (29, 32) buttons for the crossfader. When the OFF (29) button is
pressed, the left side of the crossfader will be inactive and the OFF LED (30) will
light. When the OFF (32) button is pressed, the right side of the crossfader will be
inactive and the OFF LED (33) will light. Using the OFF button, be sure to
deactivate the crossfader before changing the ASSIGN setting. This will avoid any
click or popping sound in your signal while you are changing the assign setting.
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.

Using the Ground Lift Switch

Depending on your system configuration, sometimes applying the ground will create
a quieter signal path. Sometimes lifting the ground can eliminate ground loops and
hum to create a quieter signal path.

1. With the mixer on, listen to the system in idle mode (no signal present) with the
ground applied (the GROUND LIFT SWITCH (59) in the bottom position).

2. Then turn the power off before moving the GROUND LIFT SWITCH (59). Lift
the ground by moving the GROUND LIFT SWITCH to the top position, turn the
power back on and listen to determine which position will provide a signal devoid
of background noise and hum. Keep the GROUND LIFT SWITCH in the ground
position if the noise level remains the same in either position.

CAUTION: DO NOT TERMINATE THE AC GROUND ON THE POWER MIXER IN
ANY WAY. TERMINATION OF THE AC GROUND CAN BE HAZARDOUS.

Operation

1. POWER ON: Once you have made all the equipment connections to your mixer,
press the POWER SWITCH (1). The power will turn on and the POWER LED (2)
will glow.

2. CHANNEL 1: The GAIN (14), HIGH (15), MID (16), and LOW (17) controls allow
you to fully adjust the selected source. Switch # (18) allows you to select the
PHONO 1/LINE 1 (53) or the LINE 2 (52) input. The CHANNEL SLIDE (19)
controls the input level of this channel.

3. CHANNEL 2: The GAIN (14), HIGH (15), MID (16), and LOW (17) controls allow
you to fully adjust the selected source. Switch # (21) allows you to select the
PHONO 2 (51) or the LINE 3 (50) input. The CHANNEL SLIDE (22) controls the
input level of this channel.

4. CHANNEL 3: The GAIN (14), HIGH (15), MID (16), and LOW (17) controls allow
you to fully adjust the selected source. Switch # (23) allows you to select the
PHONO 3 (49) or the LINE 4 (48) input. The CHANNEL SLIDE (24) controls the
input level of this channel.

5. CHANNEL 4: The GAIN (14), HIGH (15), MID (16), and LOW (17) controls allow
you to fully adjust the selected source. Switch # (25) allows you to select the
LINE 5 (47), LINE 6 (46) or the MIC 3 (57) input. The CHANNEL SLIDE (26)
controls the input level of this channel.

NONO

TETE

NO

TE: There is Low, Mid and High equalization for each channel

NONO

TETE

with an extremely wide range of adjustment providing a smoother
mix.

7. BPM DISPLAY: There are BPM DISPLAYS (34, 35) for the two channels
assigned to each side of the CROSSFADER (27). They update approximately
every beat and digitally display the Beats Per Minute allowing you to match the
beats visually. BPM DISPLAY (34) reflects the Beats Per Minute of the channel
assigned to the left side of the CROSSFADER, and BPM DISPLAY (35) reflects
the Beats Per Minute of the channel assigned to the right side of the
CROSSFADER.

NONO

TETE

NO

TE: A [- -] reading will appear on the BPM DISPLAY if the track

NONO

TETE

has unclear beats. The [- -] reading will also appear if there is no
signal present.

8. The BEAT OFFSET INDICATORS (36) light when the tracks of the two channels
assigned to the crossfader are within 11 BPMs of each other and display how
aligned the beats of the two channels are. When the RED LEDs light, the beats
are not aligned. When the YELLOW LEDs light, the beats are almost aligned.
When the GREEN LED lights, the beats are aligned perfectly.

NONO

TETE

NO

TE: If the diffence between the two channel’s beats exceed 11

NONO

TETE

BPM, the BEAT OFFSET INDICATORS will not light.

SUGGESTION: You can use the BPM DISPLAYS to determine which tracks
have similar or the same Beats Per Minute. When mixing two tracks with
similar Beats Per Minute, you can use one source’s pitch control to align the
Beats Per Minute with the other source’s BPM. The BPM DISPLAYS and the
BEAT OFFSET INDICATORS update every beat and will reflect the change in
BPM and indicate when the beats are aligned.

NONO

TETE

NO

TE: Beat mixing is a skill that requires practice. Not every track

NONO

TETE

has a strong beat, and beat mixing works best with tracks with
clear and strong beats.

9. OUTPUT CONTROL SECTION: The level of the AMP OUT (44, 56) is controlled
by the MASTER (41) slide and the BALANCE CONTROL (40). The BOOTH (42)
control adjusts the level of the BOOTH OUTPUT (45). HINT: The booth OUTPUT
is used by some DJs to run monitor speakers in their DJ booth. You can also use
it as a second ZONE or AMP output. Activating the MONO (39) button (the mono
LED will light) makes the master output mono.

10. 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 (9) switch controls MIC 1 and MIC 2 and has three settings.
When the MIC/TALKOVER (9) switch is in the left position, MIC 1 and MIC 2 and
talkover are off. When the MIC/TALKOVER (9) switch is in the center position

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