Sony tam 30 50 service manual

Page 2

TAM-30/ 50

SERVICE NOTE

Detection Circuit of Automatic Holding Release

This unit has a function of automatic holding release,
which separates the unit from the line when the receiver is
picked up during operation.

Figure 1 shows the detection circuit. When the line is
connected, the current flows into Q5 through R12 and R14,
and Q5 is turned on. Consequently, Q4 is turned on, and the
terminal ® of 1C3 turned to L".

When the receiver is picked up during operation, the
voltage of the line is decreased When the voltage of the line
is decreased the voltage charged on C8 is discharged through
R14l

Consequently, Q5 is cut off and Q4 is turned off. So, the
terminal 69 of ICS turned to "H and the terminal @ is turned
to L", Q2 is turned off, then the line is disconnected.

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FigI

SECTION 1
GENERAL

1-1. LOCATION OF CONTROLS

SKIP/FF button

STOP/PLAY button

REPEAT/HEW button

RESET button

Microphone

ANSWER button and message counter LED
MEMO button and lamp

OGM (outgoing message) button

TIME button (TAM»50 only)

CONVERSATION RECORD button and lamp
Battery compartment

SET/RECORD button (TAM~50 ), RECORD button
(TAM-30)

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. AUDIBLE IND (Indicator) switch
RINGER SELECT switch
VOL (volume) control
DO IN jack
TELEPHONE jack
TEL LlNE lack
Speaker
CPO switch
REC TIME switch
ID CODE-2 switch

. ID CODE-1 switch-

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