Circuit Description - Kenwood KAC-819 Service Manual

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Instruction manual (2 pages)

Instruction manual (2 pages)

Table Of Contents

Table of Contents

KAC-819

SP P-CON Switching Circuit

When the SP output from the head unit is connected to SP IN, the power can be switched ON/OFF based on the

DC voltage of the SP output. However, As certain haed unit models output DC permanently or generate a click

during switching OFF, it is required to provide the capability of previous P-CON switching. A circuit which can

perform the switching without using a switch is described below.

This circuit performs switching by inhibiting the operation of the S-P-CON circuit when a voltage is applied to the

P-CON pin.

Circuit operation description

When the head unit is connected to SP-IN, the DC component in the SP output turns Q38 ON through D32 and

R158.

When a voltage is applied to the P-CON pin under this condition, Q45 is turned ON via R188, positive feedback is

applied by combination of Q45 and Q46, Q45 and Q46 are held at ON, so the voltage at point (A) is almost 0V and

the SP-P-CON circuit is not activated.

This circuit holds the ON status while the DC voltage from SP is present.

Therefore, in this condition, the P-CON circuit continues functioning. To cancel the functioning, the voltage at the

SP-IN pin should go 0V.

No.

ITEM

IDEL

CURRENT