Saturday, April 21, 2012

Bus Board Connections

I wrote about the busboard access that several A-100 modules have earlier in this blog.
All modules that can read and/or write to the A-100's internal busboard are mentioned in THIS post.

I did forget to mention a few things in my earlier post, and thanks to the Yahoo Doepfer Usergroup i stumbled upon the A-100BC (CV/Gate bus connection cable) that can be used if the CV and/or gate signals of two bus boards have to be connected internally.

For this the CV or gate corresponding connection jumper in the middle of the bus board is removed and replaced by the connector of the (20 cm. long) A-100BC cable. 
It is possible to connect the CV and gate lines of two bus boards independently (i.e. only CV or only gate or both). 
The cable is made of two wires with suitable connectors on each side. 
Usually one wire is used for CV, the other for gate, but the wires can be ripped up and used separately. 

Dieter himself did a great post in the Doepfer Usergroup that nicely explained how the internal busboard connections work:

" The main function of the bus is the power supply of the A-100 modules (-12V, GND, +12V and additional +5V for a few modules) - In addition a CV and Gate line are available
- Some modules can pick-up the CV signal (e.g. A-110, A-111-1, A-111-5, A-143-4) from the bus depending on the jumper setting on the module (full list HERE /PP)
- Some modules can pick-up the gate CV signal (e.g. A-140) from the bus depending on the jumper setting on the module (full list HERE /PP), but most of the A-100 modules have no access to the CV or Gate signal of the bus

- Other modules may work as transmitter for the CV signal to the bus (e.g. A-190-x, A-185-x) depending on the jumper setting on the module (full list HERE /PP)

- Other modules may work as transmitter for the gate signal to the bus (e.g. A-190-x, A-185-1, A-164-1) depending on the jumper setting on the module (full list HERE /PP)
A-100 BC cable

- Pay attention that only ONE transmitter for CV and ONE transmitter for gate are allowed (otherwise modules may be damaged)

- Using the internal CV and Gate lines of the bus is optional (one may also patch the required connections via the sockets at the front panels), but using the internal CV and Gate lines may simplify the patching at the front panels (e.g. if several VCOs have to be controlled by the same CV, in this case the A-185-2 is recommended as CV transmitter to the bus, the A-185-2 allows also common octave switching and common frequency modulation of all VCOs as well as CV summing, e.g. from a sequencer and CV keyboard or Midi-to-CV interface)

- Both the CV and the Gate line can be interrupted in the middle of the bus board to establish two different CV/Gate areas.
For this the corresponding jumper in the middle of the bus board has to be removed.

- A special CV/Gate bus connection cable A-100BC is available.
This cable can be used to connect the CV and/or Gate lines of two different bus boards.
To connect the two boards the same pin headers of the two bus boards may be used that also interrupt the CV and/or Gate lines, but it is also possible to connect the corresponding pins (Gate and/or CV) of other unused bus connectors (i.e. one of the 14 16 pin connectors) "

Source: Yahoo Doepfer A-100 Usergroup