Video Interface; 48 Khz Interface; Midi Interface; Main Pcb Component Orientation - Alesis ADAT BRC Service Manual

2.3.5 Video Interface

Video synchronization is achieved through BNC connector J13. The signal fed into the BRC
from this connector is called VIDEO IN. This signal then feeds a circuit which is used to extract a
vertical sync signal. The output of this circuit is the signal VIDEO, which then is fed into the FPGA at
pin 29.

2.3.6 48 KHZ Interface

In order to sync the BRC to an external 48 KHZ source, BNC connector J15 is utilized. The
signal input to the BRC is called EXT CLK* and is fed into the FPGA through pin 44.

2.3.7 MIDI Interface

MIDI Input and Output circuitry is similar to that of ADAT syncing. The MIDI signal is input to the
BRC at MIDI connector J12, fed through opto-isolator U13, and in to the microprocessor via pin 81.
Likewise, MIDI out is transmitted from pin 80 of U10, through 2 inverters (U15C and U14C), to the
MIDI connector J11.

2.3.8 Main PCB Component Orientation

There is a uniform orientation of most components on the main PCB. Additionally, the
orientation for each component is outlined on the PCB itself, within the silk screen, Therefore, in
addition to having all the transistors facing the same direction, their outline is also silk screened on the
PCB.
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