Toshiba GD-1221, GD-1220 service manual Sound volume

Models: GD-1220 GD-1221

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The monitoring signal selected by IC9 is input to the analog switch (IC10) to select the output sound volume. The sound volume is selected by switching IC10 according to the SPVOL0-2 signals output from the ASIC and selecting an input resistance for the monitoring signal.

The relation between the signals and sound volume is as follows.

Sound volume

SPVOL2

SPVOL1

SPVOL0

 

 

 

 

Max. (7)

LOW

LOW

LOW

 

 

 

 

(6)

LOW

LOW

HIGH

 

 

 

 

(5)

LOW

HIGH

LOW

 

 

 

 

(4)

LOW

HIGH

HIGH

 

 

 

 

(3)

HIGH

LOW

LOW

 

 

 

 

(2)

HIGH

LOW

HIGH

 

 

 

 

Min. (1)

HIGH

HIGH

LOW

 

 

 

 

Silent (0)

HIGH

HIGH

HIGH

 

 

 

 

The monitoring signal whose volume is controlled by IC10 is amplified by the OP amplifier (IC17), then output to the speaker.

Signal Name

Type

Active

Description

Destination

 

 

 

 

 

TONESEL

O

H

Line/Tone Selection Signal

IC9

 

 

 

 

 

RING/TONE

O

H

Ring/Tone Selection Signal

IC9

 

 

 

 

 

SPVOL0-2

O

H

Speaker Volume Control Signals 0-2

IC10

 

 

 

 

 

*Values in [ ] are GD-1221 in case that the descriptions vary between GD-1220 and GD-1221.

GD-1220/1221

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Toshiba GD-1221, GD-1220 service manual Sound volume