Specifications

CA1 Course Notes
Sharp Electronics (UK) Limited
CE Technical Support Group Page 59
CA1 Line Stage
Within this chassis, the line driver stage does not use a coupling transformer, but a push pull driver stage,
which is similar in operation to that of the S3B chassis ( DV5131H and DV5150H ), however a few
refinements have been made to the circuit.
Driver Stage
Figure 52 : CA1 Line Driver Stage
There are a number of similarities between the circuit shown above and that of the CA10. Firstly, there
is no line driver ( impedance coupling ) transformer between the line driver and output transistor.
Secondly, the low impedance source for driving the output transistor during its on condition is provided
by a winding on the line output transformer.
As the receiver starts up the base of Q603 goes high, its emitter will drop and this will allow Q604 to turn
on and Q602 to turn off. In this condition current will flow through Q604 and R619/R616 to the -10V supply
and Q601 will be turned off. When the voltage on the base of Q603 drops, its emitter will go high and turn
on Q602 and turn off Q604. This will allow current to flow from the +7V supply ( via D619, R632, D609,
R603/4/5 and the collect/emitter junction of Q603. Q601 will now turn on and current will flow in the