Technics RS-615US-D - Page 15

ITEM MEASUREMENT & ADJUSTMENT REMARKS
R/P head LINE OUT
layback
mode
VTVM
—
Oscillosco
Test
tape
Playback
mode
VTVM
Oscilloscope
Fig. 27
. Place UNIT into record mode, and tape selector to “NORMAL”.
. Supply 1kHz signal (—24dB) from AF oscillator, through ATT, to
LINE IN.
. Adjust ATT until monitor level at LINE OUT becomes 0.42 V (— 7 dB).
. Using test tape (C-RA), make recording.
. Playback recorded tape, and make sure the value at LINE OUT on
VTVM becomes 0.42 V.
. If measured value is not 0.42V, adjust VR11 (L-CH), VR12 (R-CH)
(See fig. 36 on page 18).
. Repeat from step (2).
. For CrOz2 tape selector to “CrOz”, change test tape to (C-RF), and
take the same steps for normal.
Overall distortion
Equipment:
+ Distortion meter
* AF oscillator
* ATT
* Oscilloscope
* Test tape ---C-RA
(reference blank tape)
. Test equipment connection is shown in fig. 28.
IN
oe R/P head
ATT 600 Record
mode Test tape
Playback mode
Test tape
Distortion
meter
Fig. 28
. Supply 1kHz signal to LINE IN and adjust ATT so that output level
at LINE OUT indicates 0.42 V (— 7 dB).
. Make recording.
. Playback and measure distortion factor of output signal.
. When the distortion factor does not satisfy the standard, check the
bias current. When the bias current is lower than standard, distortion
will increase.
Care should be exercised in the adjustment because the bias current
also has an influence on the overall frequency response. Refer to
“The overall frequency response” and “The bias current adjustment”.
Standard value:
Less than 2.3% (Normal)
Less than 3.3% (EX)
Less than 3.3% (CrO2)
* LINE IN level control
we MAX
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