Brother PT-H100 Service Manual page 14

The locking boss on the cassette sensor holder enters the locking boss hole on the
tape cassette, and the cassette sensor switches are held down according to the holes
on the tape cassette. (The cassette sensor turns ON when the sensor switches that
correspond to the sections without holes are held down.)
The tape cassette type and width are determined depending on the pattern that the
cassette sensor switches are held down. (The tape cassette type and width are
determined depending on the holes (1, 2 or 3) at the section "A".)
"A"
Figure 2.1-7 Cassette Sensor Mechanism
Tape cassette
Locking boss hole
Cassette sensor hole
II - 5
Locking boss
Cassette sensor
switches (3 pcs.)
Cassette sensor
The switch at this
position does not
exist on the actual
part.