Sony BVW-55 Maintenance Manual page 216

3-1. General Information on Parts Replacement and Alignment
To enter the threading end state with the cassette compartment removed
(during tape path adjustment)
(1) Set switch S100-1 on the SV-206 board to ON.
(2) Turn on the power.
(3) Press the EJECT button. (If not, an error will be detected due to the threading end state.)
(4) Press the STOP button.
(5) Put the cassette tape without lid on the mechanical deck and put a weight.
Reference
. Use a weight of about 1000 g.
. As for how to remove a lid from the cassette tape, refer to section 5-1.
S100 switch
1
Cassette tape without lid
Weight (about 1000 g)
3-4
BVW-55 P2