HCD-GT220, HCD-GT440, HCD-GT660, MHC-GT220, MHC-GT440, MHC-GT660 - Sony Audio Service Manual (repair manual). Page 15

The cold reset clears all data including preset data stored in the 
RAM to initial conditions. Execute this mode when returning the 
set to the customer.
Procedure:
1.  Press three buttons of [

x

], [

u

] and [GROOVE] simultane-

ously.

2.  The message “COLD RESET” is displayed on the fl uorescent 

indicator tube momentarily, then becomes standby states.

A step of AM tuning interval can be changed over between 9 kHz
and 10 kHz.
Procedure:
1.  Press the [

?/1

] button to turn the power on.

2.  Press the [TUNER/BAND] button to select “AM”.
3.  Press the [

?/1

] button to turn the power off.

4.  Press two buttons of [TUNING +] and [

?/1

] simultaneously.

5.  The message “AM 9K STEP” or “AM 10K STEP” is displayed 

on the fl uorescent indicator tube, and thus the tuning interval is 
changed over.

This mode moves the optical pick-up to the position durable to 
vibration. Use this mode when returning the set to the customer 
after repair.
Procedure:
1.  Press the [

?/1

] button to turn the power on.

2.  Press the [CD] button to select “CD”.
3.  Press two buttons of [

u

] and [

?/1

] simultaneously.

4.  The message “LOCK” is displayed on the fl uorescent indicator 

tube, and the CD ship mode is set.

This mode is used to perform CD ship (lock) mode and cold reset 
simultaneously.
Procedure:
1.  Press the [

?/1

] button to turn the power on.

2.  Press the [CD] button to select “CD”.
3.  Press three buttons of [

x

], [ILLUMINATION] and [

?/1

] si-

multaneously.

4.  The message “COLD RESET” is displayed on the fl uorescent 

indicator tube momentarily, then becomes standby states.

This mode is used to unable to take sample disc out of disc table 
in the shop.
Procedure:
1.  Press the [

?/1

] button to turn the power on.

2.  Press the [CD] button to select “CD”.
3.  Insert a disc.
4.  Press two buttons of [

x

] and [

Z

] for 5 seconds.

5.  The message “LOCKED” is displayed on the fl uorescent in-

dicator tube and the disc table is locked. (Even if pressing the 
[

Z

] button, the message “LOCKED” is displayed on the fl uo-

rescent indicator tube and the disc table is locked)

6.  To release this mode, press two buttons of [

x

] and [

Z

] for 5 

seconds.

7.  The message “UNLOCKED” is displayed on the fl uorescent 

indicator tube and the disc table is unlocked.

This mode is used to display the parameter of amplifi er IC and
display the VACS status.
Procedure:
1.  Press the [

?/1

] button to turn the power on.

2.  Press three buttons of [

x

], [

u

] and [USB] simultaneously.

3.  When the AMP test mode is activated, the message “AMP 

TEST IN” is displayed on the fl uorescent indicator tube mo-
mentarily, then amplifi er adjustment mode is displayed on the 
fl uorescent indicator tube.

4.  Press the [TAPE REC PAUSE/START] button to changed over 

between VACS status display mode and the amplifi er IC pa-
rameter display mode.

5.  In this mode, press the [GROOVE] button to changed over 

DBFB on/off, and “DBFB ON” or “DBFB OFF” is displayed 
on the fl uorescent indicator tube.

6.  In this mode, press the [SURROUND] button to changed over 

surround on/off, and “SURROUND ON” or “SURROUND 
OFF” is displayed on the fl uorescent indicator tube.

− For GT220/GT440 −
7.  In this mode, press the [EQ BAND] button to enter the equal-

izer adjustment mode.

 

In the equalizer adjustment mode, press the [EQ BAND] but-
ton to change over the adjustment band as LOW/MID/HIGH. 
And turn the [OPERATION DIAL] knob to adjust the equal-
izer level of each bands.

− For GT660 −
7.  In this mode, press the [BASS], [VOCAL] or [GUITAR] but-

ton to enter the parametric equalizer adjustment mode.

 

In the parametric equalizer adjustment mode, press the [BASS], 
[VOCAL] and [GUITAR] button to change over the adjust-
ment band. And press the [BASS], [VOCAL] or [GUITAR] 
button to change over the equalizer frequency of each bands, 
or press the [+] and [

−] buttons to adjust the equalizer level of 

each bands.

8.  To release the amplifi er IC parameter display mode or equal-

izer adjustment mode, press the [

?/1

] button to the power off.

This mode is used to check operations of microprocessor.
Procedure:
1.  Press the [

?/1

] button to turn the power on.

2.  Press three buttons of [

x

], [

u

] and [AUDIO] simultaneous-

ly.

3.  When the MC test mode is activated, VACS level is displayed 

on the fl uorescent indicator tube momentarily.

4.  Press the [TUNING +] button, the message “ALL EQ MAX” 

is displayed on the fl uorescent indicator tube momentarily and 
press the [TUNING 

−] button, the message “ALL EQ MIN” is 

displayed on the fl uorescent indicator tube momentarily.

5.  Press the [ENTER] button, the message “ALL EQ FLAT” is 

displayed on the fl uorescent indicator tube momentarily.

6.  Turn the [VOLUME] knob clockwise, the message “VOL-

UME MAX” is displayed on the fl uorescent indicator tube 
momentarily and turn the [VOLUME] knob counterclockwise, 
the message “VOLUME MIN” is displayed on the fl uorescent 
indicator tube momentarily.

7.  Press the [TAPE REC PAUSE/START] button to changed over 

VACS on/off.

8.  Press the [

?/1

] button to release from this mode, then cold 

reset is performed.