Technics RS-676US - Page 12

ITEM
MEASUREMENT & ADJUSTMENT
REMARKS
Playback Frequency
Response
Equipments:
* VTVM
* Oscilloscope
* Test Tape...C-FH
Playback Gain
Equipments :
* VTVM
* Oscilloscope
* Test Tape...C-FH
. Test equipments connection is as same as “Head Azimuth
Adjustment” but use- the test tape (C-FH) in stead of
head azimuth tape (See fig. 12).
. Place UNIT into playback mode.
. Play frequency response test tape (C-FH).
. Measure output level at 10kHz, 8kHz, 4kHz, 1 kHz, 125
Hz and 63Hz and compare output level with standard
frequency 333 Hz, at LINE OUT.
. Make measurement for both channels.
. Make sure that the measured value is within the range
specified in the frequency response chart.
Playback Frequency Response Chart
+5 dB 333 Hr
0 dB
—14dB
63 Hz 125 Hz VkHz = 4 kHz 8 kHz
Fig. 17
. lf measured value is not in standard, adjust VR1 (L-CH),
VR2 (R-CH) (See fig. 30 on page 19).
. Test equipments connection is shown in fig. 12.
. Play standard recording level portion on test tape (C-FH
333Hz) and, using VTVM, measure the output level at LINE
OUT jack.
. Make measurement for both channels.
Standard Value: 0.42 V (— 7 dB)
Adjustment
Le
2
If measured value is not standard, adjust VR3 (L-CH), VR4
(R-CH) (See fig. 30 on page 19).
After adjustment, check ‘Playback Frequency Response”
again.
* Playback Mode
* Playback Mode
Playback S/N Ratio
Equipments:
* VTVM
+ Oscilloscope
* Test Tape...C-FH
* Empty Cassette
. Test equipments connection is shown in fig. 12.
2. Play standard recording level test tape (C-FH 333Hz) and
read output level on VTVM.
Refer to “Playback Gain Adjustment”.
. Place empty cassette (which has been cut) and play gain
without moving adjusted playback VR.
. Measure noise level at this time using VTVM, and deter-
mine ratio of this level to test tape output signal voltage
(333 Hz).
Standard Value: Greater than 45 dB
An example calculation is shown below.
A: Es=playback output signal voltage of test tape (333 Hz)
B: En=playback output noise level
Es=0.42V (—7 dB)
En=2.5 mV (—52dB)
S/N ratio= ES _.
S/N ratio=Es (dB) —En (dB) = —7— (-52) =45dB
*« Playback Mode