Kurzweil SP5-8 - SP5 Getting Started - Pedal Connections; Connecting Pedals

Printed Circuit Boards
Function Overview
2-6
Right and Left Front Panel PCBs
ScanPort interface to front panel LED indicators
(page 1 zone C5–D5)
The 25 LEDs on Right Front Panel PCB are in a 6 column 7 row matrix. The column select
shift register (U1) drives the next column each time the ScanPort writes new data into the
LED row register (U3). A new scan begins when the ScanPort RES signal is low during a row
register write cycle. Scan rate is approximately 100Hz (10mS).
The column select shift register outputs are current boosted by transistors Q1–Q5 and Q23.
LEDs light when the column they are connected to is low and the row is high.
The 18 LEDs on the Left Front Panel PCB are in a 5 column 4 row matrix. Their signals are
passed through the Control Panel Bridge connector to the Right Front Panel PCB.
ScanPort interface to front panel buttons
(page 1 zone B5)
The 26 buttons on Right Front Panel PCB are in a 6 column 5 row interface. The columns are
shared with the LEDS. The status of the rows is driven back to the ScanPort by buer U4. A
pressed button will send back a zero for its row position when its column select line is low.
Buttons that may be pressed simultaneously are never on the same row.
The 18 buttons on the Left Front Panel PCB are in a 6 column 3 row matrix. Their signals are
passed through the Control Panel Bridge connector to the Right Front Panel PCB.
Right Front Panel PCB
ScanPort interface to the keyboard
(page 2 zone B1–D3)
The keyboard connects to J3 (treble half) and J5 (bass half). Bass is a 10 column by 8 row
matrix (40 keys, 80 switches) and treble is a 12 column by 8 row matrix (48 keys, 96 switches).
These are combined into a 22 column by 8 row matrix for 88 keys total.
Shift registers U9, U8, U5 drive the columns low one at a time. Buer U12 transmits the state
of the rows back to the ScanPort. Each time a row is read, the column shift registers advance
one column. A new scan begins when the ScanPort RES signal is low during a keyboard row
read cycle. Scan rate is approximately 4KHz (250uS).
MIDI In/Out connector interface
(page 2 zone D4–D6)
U6 is the MIDI In current loop receiver. Either a PC910 or a 6N138/6N139 may be used. The
components around U6 will be dierent according to the Usage Table. U7-A and U7-B drive
the MIDI Out connector current loop.