1. INTRODUCTION

MSY1 is an interface that converts the MIDI realtime events CLOCK, START and STOP into the corresponding signals CLOCK and START/STOP of the SYNC standard. The SYNC standard is used in vintage drum computers or sequencers such as the Roland TR808 rhythm composer or the TB303 bass line. SYNC-CLOCK is a periodic TTL signal (0/+5V) representing the tempo. SYNC-START/STOP is a signal that indicates on the 2 possible states: START = +5V, STOP = 0V. MSY1 enables the 1:1 conversion of MIDI CLOCK to SYNC CLOCK i.e. 1 MIDI clock triggers 1 SYNC clock pulse, as well as the reduction of the tempo by dividing the incoming MIDI clock frequency by an integer factor. The factor can be set to any value between 1 and 128. 1 corresponds to the 1:1 conversion, 128 is the maximum of frequency reduction, i.e. after 128 MIDI clocks 1 SYNC clock appears .
The SYNC standard uses the same type of 5 pole 180ø DIN connectors as MIDI. But the standards do not fit as other pins are used and the signals are completely different! So you always have to distinguish between the MIDI and SYNC connectors. The pinout of the SYNC standard you may find at the end of this manual.
Using a suitable cable (e.g. 5 pin DIN plug -> two 1/4" mono jack plugs) the CLOCK and/or START/STOP outputs of the MSY1 may be used to control arpeggio, gate, trigger or other +5V/TTL controlled events of analog synthesizers via MIDI.


2. CONNECTIONS

MSY1 does not have a built-in power supply. Instead it uses a plug-in type EXTERNAL POWER SUPPLY (AC adapter). The power supply is NOT included with the MSY1 and must be purchased locally by the user. We recommend the DOEPFER PS1 AC adapter (VDE approved) but MSY1 will work with every AC adapter being in accordance with the following specifications. The adapter must be able to deliver 7-12 V DC unstabilized voltage, as well as a minimum current of 300 mA. The POLARITY of the low voltage plug connected to the MSY1 must be pin = +7...12V and ring = GND. If the polarity is incorrect, MSY1 will not function. However, there is no danger of damage to the circuitry since it is protected by a diode. If the MSY1 is used in Germany the external power supply should be VDE approved like the PS1.
The MSY1 is SWITCHED ON by plugging the AC adapter into a wall outlet and connecting it to the jack labeled "9V DC" of the MSY1. There is no separate ON/OFF switch.

Connect MIDI IN of the MSY1 to MIDI OUT of the MIDI transmitter (MIDI masterkeyboard, sequencer). The MIDI THRU of the MSY1 may be connected to MIDI IN of other MIDI devices (optional).

Connect the SYNC output of the MSY1 to the SYNC (-In) socket of the device to be controlled by the MSY1. Use a suitable cable for that. The pins 1, 2 and 3 must be connected! MIDI cables are unsuitable! If the SYNC socket of your device can be switched between SYNC-IN and SYNC-OUT switch it to SYNC-IN (e.g. TR808). If your device is equipped with SYNC-IN and SYNC-OUT use SYNC-IN.


3. OPERATION

After power on the two LEDs near the SYNC will flash up shortly. Otherwise the AC adapter used is not suitable or does not work.

In case of an incoming MIDI START event (normally followed by MIDI CLOCK signals) the START LED will light up and the CLOCK LED will flash indicating the tempo. Because of the inertia of the eye higher frequencies are not perceptible.
In case of an incoming MIDI STOP event both LEDs turn off independent of eventually incoming MIDI CLOCK events.
If the SYNC output of the MSY1 is connected faultless to your device it should respond to the MIDI events, i.e. start, stop and change the tempo via MIDI. If the two LEDs of the MSY1 display properly but your device does not respond there is probably a fault in the connection between MSY1 and your device (unsuitable cable) or the SYNC input of your device is not switched to SYNC-In.

If you want to slow down the SYNC clock frequency you may change the CLOCK DIVIDING FACTOR. The factory setting 1:1 conversion. To change the setting you have to open the case. Disconnect all cables from the MSY1, remove the 4 screws of one of the 2 plates and pull out the cover plate. Inside you may find a 8 pole DIP switch or 8 jumpers depending upon to the type of MSY1. With 7 of the 8 switches or jumpers the dividing factor is set between 1 (i.e all switches on/all jumpers set) and 128 (i.e. all switches off/all jumpers removed). The valence of the switches/jumpers increase in the 2's power rule (1, 2, 4, 8, 16, 32, 64). You may find details in the sketch at the end of this manual. You have to add 1 to the calculated value to get the actual dividing factor as the range begins with 1 instead of 0. But normally you will not have to calculate the dividing factor rather you try some switch/jumper settings to find the desired SYNC clock divider. As a rule only the lower factors (1:1 ... 1:8) are making sense.
Pay attention that some of the devices to be controlled by MSY1 additionally enable to change the dividing factor inside the device (e.g. TR808: "prescale").

The last of the 8 switches/jumpers corresponds to CLOCK POLARITY i.e. whether a falling or rising edge appears on the SYNC clock output when a MIDI clock is received. Normally this setting is of no account as the clock pulse width (i.e. the time difference between the falling and rising edge) is very small (about 4 milliseconds in the 1:1 setting). If you have the impression that there is a small time difference between your device and MIDI clock you should change the setting of the clock polarity.

In the jumper version of the MSY1 you may find an additional 16 pin connector on the pc board. This connector is intended for taking up unused jumpers to keep them from loss.