This patch bay MIDI is designed to use with a sequencer/computer, a master keyboard and 8 MIDI instruments.

Features

• Inputs
  • 8 to 1 by the digital selector
  • 1 Master Keyboard IN
  • 1 Sequencer Insert IN
    
  
  
• Outputs
  • 8 out (version 3.2) OR 2 group of 4 out each (version 3.1)
  • 1 Sequencer Insert OUT
    

• Midi merge based on 8031 microcontroler
  
• 2 push buttons and 2 x 7segment leds on front panel
• input selector and mode/output control
  
• 2 signal leds, 1 merge overflow led
  
• Programmableconfiguration at power on .
  
• Rack 19"-1U psu 230Vac /5Vdc

Synoptics

There is two versions of the MPB3 with different configurations of routing. The most useful for Home Studio, sequencer work is the v3.2... Both work well anyway.

• The MPB3 v3.1 perform 4 MIDI output configurations... Synotpic v3.1
• The MPB3 v3.2 have 2 configurations :Synoptic v3.2. The merger is connected before (PRE) or after (POST) the insert sequencer plugs (INS) by a set of electronic switches. This is very handful for sysex edition.

Note the MK IN plug is for the Master Keyboard MIDI Out...
Plugs INS IN et INS OUT (INsert Sequencer) are respectively for MIDI OUT and IN of the sequencer/cpu

Schematics,pcb, eprom

• MIDI Input Selector 8>1 and Alim
• MIDI merger and output system v 3.1
• MIDI merger and output system v3.2
• Bill of materials ...(txt)

All PCB draws of the MPB3 in Gif + the merge eprom bin file and other related stuff are in MPB3GIF.ZIP (286K ). Provided pcb are for 6 or 8 pins dip optos like 6N135...6N138, best ones for MIDI applications.