Behringer PRO-1 User manual

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985-40000-01090 Rev.A
2021-02-16
Condential, for internal use only. Not to be reproduced.
The unit is carefully calibrated at the factory. The performance may change over time or due to environmental changes,
and the following recalibration procedures can be used to bring it back to its factory settings. If you do not feel comfortable
doing these calibrations, then we recommend they are done by an experienced audio service technician. This is especially true
for those units that need to be opened to gain access to voltage test points and calibration potentiometers.
CAUTION: Incorrect calibration or damage to the delicate adjustment potentiometers may lead to the unit
becoming inoperable.
Note: Although re-calibration will not invalidate the warranty, any damage caused during re-calibration may invalidate
the warranty.
Analog Synthesizer with Dual VCOs,
3 Simultaneous Waveforms, 4-Pole VCF,
Extensive Modulation Matrix, 16-Voice
Poly Chain and Eurorack Format
Synthesizers and Samplers
PRO -1
User Support Document
Equipment required
1. Small insulated trimmer screwdriver.
2. Small Phillips screwdriver.
3. A at sheet of cardboard or another insulator as wide as the PRO 1. (This will help prevent damage to the top panel when it is
inverted and resting on the bottom chassis).
4. Digital DC Voltmeter with a scale that can display accurately to 0.001 V.
5. Guitar tuner
6. An external MIDI keyboard of at least 6 octaves including A1 and A7.
7. MIDI cable.
8. Pair of headphones or a sound system to monitor the main output.
Important Note:
Leave the PRO 1 turned on for approximately 30 minutes. This will allow the circuits time to warm up and the components and
performance to stabilize with temperature. Without this warm-up time, the calibrations
will be inaccurate.
Introduction

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985-40000-01090 Rev.A
2021-02-16
Condential, for internal use only. Not to be reproduced.
page 2 of 6
Turn over the top panel to gain access to the bottom surface of the printed circuit board (pcb). Be careful not to strain
the ribbon cables. Use the cardboard to protect the top panel.
Caution:
Make sure that the circuit board is not touching any bare metal that may cause a short circuit and damage the unit.
Do not touch the circuit board while the unit is powered up.
Remove the 8 screws holding the top panel to the chassis.
Preparation
Remove all cables and connections to the unit.
Carefully connect the power and turn on the unit.
Leave the unit turned on for approximately 30 minutes.
Synthesizers and Samplers
PRO -1
Follow all steps in the order in which they are presented.

page 3 of 6
985-40000-01090 Rev.A
2021-02-16
Condential, for internal use only. Not to be reproduced.
page 3 of 6
Synthesizers and Samplers
PRO -1
Oscillator Calibration using a guitar tuner:
Figure 1
Calibration Procedure
OSCA Calibration
Turn on the OSCA SAW switch.
The positions of knobs and switches are shown in red on Figure 1.
On your external keyboard, press the A1 key and adjust the OSCA FREQUENCY on the front panel to zero while
observing the tuner display. A1 should be 55 Hz.
Connect a guitar tuner to the rear panel main ¼" output.
Note that a pitch within 2 to 3 cents of the target frequency should be ne.
Please pay special attention to the FREQUENCY knobs of Oscillator A and B.

page 4 of 6
985-40000-01090 Rev.A
2021-02-16
Condential, for internal use only. Not to be reproduced.
page 4 of 6
Synthesizers and Samplers
PRO -1
OSCB Calibration
Turn on the OSCB SAW switch and KYBD.
On your external keyboard, press the A1 key and adjust the OSCB FREQUENCY on the front panel while
observing the tuner display.
On your external keyboard, press the A4 key and adjust the OSCB SCALE trimmer while observing the tuner display.
Repeat steps 3 and 4 until both frequencies are correct A1 - 55 Hz and A4 - 440 Hz.
On your external keyboard, press the A7 key and adjust the OSCA TRIM trimmer while observing the tuner display.
Turn OFF the OSCA SAW switch.
Press A1 key again check how much the frequency has drifted and adjust this frequency with
OSCA OFFSET trimmer back to 55 Hz.
On your external keyboard, press the A4 key and adjust the OSCA SCALE trimmer while observing the tuner display.
This should be trimmed to 440 Hz.

page 5 of 6
985-40000-01090 Rev.A
2021-02-16
Condential, for internal use only. Not to be reproduced.
page 5 of 6
Synthesizers and Samplers
PRO -1
Connect the positive probe of your Voltmeter to TP3.
OCTAVE Calibration (factory mode)
Set the Digital Voltmeter to measure a range below 10 VDC.
Locate the Test Points OCTAVE CV TP3 and ground (the red arrow in Figure 2) on the bottom surface of
the main PCB.
Figure 2
Repeat the same steps as oscillator A but using OSCB SCALE and OSCB OFFSET trimmers.
On your external keyboard, press the A7 key and adjust the OSCB TRIM trimmer while observing the tuner display.

page 6 of 6
985-40000-01090 Rev.A
2021-02-16
Condential, for internal use only. Not to be reproduced.
page 6 of 6
Condential, for internal use only. Not to be reproduced.
Music Tribe accepts no liability for any loss which may be suered by any person who relies either wholly or in part upon any description, photograph, or statement contained herein.
Technical specications, appearances and other information are subject to change without notice. All trademarks are the property of their respective owners. Midas, Klark Teknik,
Lab Gruppen, Lake, Tannoy, Turbosound, TC Electronic, TC Helicon, Behringer, Bugera, Oberheim, Auratone and Coolaudio are trademarks or registered trademarks of Music Tribe Global
Brands Ltd. © Music Tribe Global Brands Ltd. 2021 All rights reserved.
Synthesizers and Samplers
PRO -1
Connect the negative probe of your Voltmeter to ground.
Turn o the power and unplug the power connector.
Measure the output voltage. It should read +2.000 VDC.
Make sure the internal connections are still correctly inserted and secured.
If not, then adjust the OCT ADJ potentiometer until the measured output voltage is +2.000 VDC.
Ret the top panel back into the bottom chassis and secure with all the screws.
This calibration is done after the oscillator calibration. The positions of knobs and switches are shown in red on Figure 1.
Connect a guitar tuner to the rear panel main 1/4" output.
OCTAVE Calibration (user mode)
Turn on the OSCA SAW switch.
Set the position of the OCTAVE switch to 0. On your external keyboard, press the A1 key.
Set the position of the OCTAVE switch to 3. Adjust the OCT ADJ trimmer until there are zero beats.
End of Procedure