Ribbon Encoder - Tally Dascom 7010 Series Maintenance Manual

2-2. Operation of Control Parts

(7) Ribbon encoder

The ribbon encoder is a photo interrupter to detect ribbon running and ribbon end, and is
incorporated in the ribbon unit (Unit, Frame Ribbon L). A bladed wheel is mounted on the
supply reel of the ribbon unit. When the supply reel turns, the blades intermittently block the
light emitted from the LED of the ribbon encoder. Thus, while the ribbon is running (supply reel
is rotating), a pulse train is input to pin 76 (RIBENC) of U1 (CPU). With this pulse input, the
CPU can detect tape running and tape end.
U1 CPU
76
RIBENC
A0
+3.3V
R130
R128
R129
C87
[Main PCB]
2-28
Ribbon Unit
Ribbon Encoder
J8
(Ribbon Running/
Ribbon End Sensor)
1
2
3
4