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Confirmation of dbx
decode effect
Condition:
* Playback mode
Equipment:
*VTVM
* ATT
* AF oscillator
* Stereo M3 plug
. Supply 315 Hz signal from AF oscillator through 4 estilator
. Remove three lead wires of head by desoldering.
. Test equipment connection is shown in fig. 2 and
11.
. Set dbx switch to IN.
. Load a cassette tape (to defeat auto-stop
function), and set the unit to playback mode.
=
ATT (for —78dB attenuation) to head lead wire
terminal (on FPC) (for both channels) as shown
Head lead wire terminal
Headphones jack
Playback mode
control (VR2).
signals are inputted.
. At this time, measure output level, and adjust
measured value to 50 mV by adjusting volume
. Next, attenuate 315 Hz signal by —66dB and
—86 dB, and measure output levels when these
. Perform measurement for both channels.
. Check that the measured values meet the
requirements in the dbx decode eftect table.
dbx decode effect table
Input signal
|
Measured value
~76dB (315Hz) |
OdB (50 mV)
—66 dB (315Hz) |
+2043 dB (500mvV)
—86 dB (315Hz)
ELECTRICAL PARTS LOCATION
REPLACEMENT PARTS LIST
Part Name & Description
ELECTRICAL PARTS
E1
QWY4142Y
Playback Head
E2
QES1533
Brush Holder Assembly
E3
WM034BZ103
Condenser Microphone
E4
QKJ0502
Microphone Holder
E5
QKJ0501
Holder
E6
QGT1562
Switch Knob (for Pause)
E7
QYTO639W
Volume Knob
E8
QQC1735
Shelter
EQ
QTS1590
Shield Plate
E 10
QBHO0081
Insulating Sheet
Et
QTD1258
Lug Terminal
E 12
XQN16+A3FZ
Screw @1.6x3
E13
XQN16 + A35FR Screw @1.6x3.5
E14
XQN16+C4FY
Screw @1.6x4
E15
XTNQI6C4FFR
Screw @1.6x4
E16
QHQ1320
Step Screw
E17
-
QBH0180
Protection Sheet
E 18
QYT0654
Switch Knob (for dbx)
E19
XTNQ16C28F
Tapping Screw @1.6x2.8
E 20
XTNQ16A3F
Screw @1.6x3
E21
QTW1242
Insulating Sheet
—20+3dB (5mV)
E20
E5
£19
6002
6002
Main circuit board (back side)
Fig. 12
Ett
'E13
E18
E12
E15
E9
EA,
E16
Tape speed
adjustment VR
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