Technics RS-615US-D - Page 13

Playback gain
Equipment:
*VTVM
* Oscilloscope
* Test tape---C-FH
MEASUREMENT & ADJUSTMENT
. Test equipment 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: 0.42V (—7dB)
Adjustment
1. If measured value is not standard, adjust VR1 (L-CH), VR2 (R-CH)
(See fig. 36 on page 18).
2. After adjustment, check “Playback frequency response” again.
REMARKS
* Playback mode
Playback S/N ratio
Equipment:
* VTVM
* Oscilloscope
* Test tape--- C-FH
* Empty cassette
Recording current
. Test equipment connection is shown in fig. 12.
. Play standard recording level test tape (C-FH 333Hz) and read out-
put level on VTVM.
Refer to “Playback gain adjustment”.
. Place empty cassette (which has been cut) and play again.
. Measure noise level at this time using VTVM, and determine ratio of
this level to test tape output signal voltage (333 Hz).
Standard value: Greater than 43dB
An example calculation is shown below.
A: Es = playback output signal voltage of test tape (333Hz)
B: En=playback output noise level
Es=0.42V (—7dB)
En=0.003 V (—50dB)
: Es 0.42V
S/N ratio = En = 0.003V 140
20 logis 140 = 43dB
S/N ratio= Es (dB) —En(dB) = —7—(—50)= 43dB8
LINE IN
Record mode
R1(L-CH)
R2(R-CH)
R/P Head
Fig. 23
. Test equipment connection is shown in fig. 23.
. Stop bias oscillation by unsoldering the connection point for bias cur-
rent ON or OFF in fig. 22.
. Supply 1 kHz signal (— 24 dB) again and adjust ATT until monitor level
at LINE OUT becomes 0.42 V.
. Measure voltage and then calculate recording current by formura given
below.
Value read on VTVM (V)
Recording current = 10 @)
Standard value:
0.42 mV: 42nA (Normal)
0.44 mV: 444A (EX)
0.60 mV: 60xzA (CrO2)
. Adjust VR11 (L-CH), VR12 (R-CH) (See adjustment part location on
page 18).
* Playback mode
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