Technics RS-M7 Service Manual page 5

Overall gain
Condition:
* Record/playback mode
* Input level control --- MAX
* Standard input level;
MIC «+++ —72+3dB
LINE IN --- —2443dB
Equipment:
* AF oscillator *VTVM
* Oscilloscope * ATT
* Test tape
(reference blank tape)
«++ QZZCRA for Normal
Level meter
Condition:
* Record mode
* Input level control --- MAX
Equipment:
* VTVM
* AF oscillator
* Oscilloscope
* ATT
Overall frequency response
Condition:
* Record/playback mode
* Input level control --- MAX
Equipment:
* VTVM
* AF oscillator
* ATT
* Test tape
(reference blank tape)
+++ QZZCRA for Normal
«++ QZZCRX for CrO2
«++ QZZCRY for Fe-Cr
Overall frequency response
adjustment
(As a standard for adjustment)
ITEM MEASUREMENT & ADJUSTMENT
10.
Adjustment 1—Using bias current
1.
Record mode
Adjust ATT until monitor level at LINE OUT becomes 0.39 V. UNEIN Test tape
. Using test tape, make recording. LINE OUT 8
. Playback recorded tape, and make sure the value at LINE OUT pier a ©
on VTVM becomes 0.39V. o fe)
. If measured value is not 0.39, adjust VR5 (L-CH), VR6 Test tape P#yback mode VTVM — Oscitioscope
(R-CH) (See fig. 21 on page 5). Fig. 14
. Repeat from step (2).
. Test equipment connection is
. Load reference blank test tape and
. Supply 1kHz signal from AF
. Adjust ATT so that input level is
. Record each frequency 50 Hz,
. Set the tape selector to CrOz,
. Measure as same as manner
RS-M7
Test equipment connection is shown in fig. 14.
Place UNIT into record mode, and tape selector to normal
position.
Supply 1 kHz signal (—24 dB) from AF oscillator, through ATT,
to LINE IN.
AF oscillator
Test equipment connection is shown in fig. 15.
Supply 1kHz signal from the AF oscillator, through the ATT,
to the LINE IN jack.
Adjust ATT so that the monitor level at LINE OUT becomes
0.39V.
Adjust VR501 (L-CH) and VR502 (R-CH) so that the level
meters indicate 0 dB.
LINE OUT
LINE IN
AF oscillator
Overall frequency response chart (Normal)
1OKH
Skee |
}
shown in fig. 14.
place UNIT into record mode.
oscillator through ATT to LINE IN.
—20dB below standard recording
level (standard recording level
—24 dB).
Fig. 16
100Hz, 200Hz, 1kHz, 2kHz,
4kHz, 8kHz and 10kHz (12kHz
for CrO2 and Fe-Cr tape) at the
same level.
Playback and express in dB the
difference between playback
output level of each frequency
based on playback output level of
1kHz.
Make sure that the measured value
is within the range specified in the
overall frequency response chart.
Overall frequency response chart (Fe-Cr)
SkHz
12kHz
a
ad 2kHZ
!
kHz
{
Fig. 17
Overall frequency response chart (CrO2)
Fe-Cr position.
2itz
5]
kHz
{
above.
Make sure that the measured value
is within the range specified in the
overall frequency response chart
for CrO2 and Fe-Cr tape shown in
fig. 17 and 18.
Fig. 18
When the frequency response between the middle and high-
frequency range becomes higher than the standard value, as
shown by the solid line in fig. 19, increase the bias current by
turning L5 (L-CH), L6 (R-CH).
When it becomes lower, as shown by dotted line, reduce the
bias current by turning L5 (L-CH), L6 (R-CH).
OmHs 11 RMe
aemr amy
Fig. 19