Technics RS-TR979 Service Manual

RS.TR979 j
PLAYBACK FREQUENCY RESPONSE (DECK 1/2)
1. Playback the frequency response portion (315Hz, 12.5kHz-
63Hz, -20dB) of the test tape (QZZCFM).
2. Assure that the frequency response is within the range
shown in Fig. 6 for both L-CHand R-CH.
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Fig. 5
ERASE CURRENT ADJUSTMENT (DECK 1/2)
1. Insert the Metal. blank test tape (QZZCRZ)and set the unit to
the Record Pause mode.
2. Check if the output at this time between the erase current
confirmation point Deck 1=TP351 (Deck 2=TP301) and GND
(chassis) (the output on both edges of Deck 1=R358 (DECK
2=R308)) is within the standard value.
Standard value: 180:t20mA (Metal)...EVMReading: 180:t20mV
OVERALL GAIN ADJUSTMENT AND OVERALL
FREQUENCY RESPONSE (DECK 1/2)
1. Load a Normal blank test tape (QZZCRA)into the deck under
test. Press the ATC button, then the REC button. (At this
point the deck automatically adjusts the overall gain and
frequency response.)
2.
With the deck placed in Record. Pause mode, apply the
reference test signal (1kHz) to the Rec. input and adjust the
output level to 320mV with the attenuator (ATT). After this,
start recording.
3. While playing back the reference signal just recorded, veri~y
that the output level falls in the following range.
I Standard value: 320mV:tO.5dB I
4. Apply test signals (with the specified test frequencies
covering the range from 50Hz to 10kHz) whose levels are
20dB lower than the reference signal level (1kHz) to the Rec.
input and record these signals in sequence.
5. Play back the test signals just recorded and verify that the
levels at the test frequencies fall in the ranges specified in
Fig. 8 with respect to the reference signal level.
6. Repeat steps 4 and 5 above for CrO2blank test tape (QZZCRX)
and Metal blank test tape (QZZCRZ),in these cases raising
the upper end of the test signal frequency range to 12.5kHz.
Verify that the signal levels at the test frequencies fall in the
ranges specified in Fig. 9 with respect to the reference signal
level.
7. Perform the same checks for both DECK1and DECK2.
Steps 1 through 4 above are concerned with overall gain;
steps 5 through 7 pertain to overall frequency response.
Fig. 10
+6dB'
+4dB
+3dB'
+2dB
I
Ode
-2dB'
-3dB
-4dB
-6dB
+5dB
+3dB
+2dB
Ode
2dB
3dB
-5dB
315HZ
8kHz
Fig. 6
DECK1: IIil!II
DECK2:IIil!II
ERASE HEAD
EVM
(Electronic
Voltmeter)
+.
Fig. 7
Norma' Overall frequency respon.. chart (NROUT)
+6dB
+4dB
+2dB
Ode
-2dB
-4dB'
-6dB
+4dB
Ode
-3dB
50HZ 100Hz 200Hz 500Hz 1kHz 2kHz
10kHz
Fig. 8
crOz Meta' Overall frequency respon.. chart (NR OUT)
+6dB
I
+4dB
+2dB
I
Ode
-2dB
-4dB
-6dB
+5dB
Ode
-4dB
50HZ 100Hz 200Hz 500Hz 1kHz 2kHz 12.5kHz
Fig. 9
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63Hz 100Hz 200Hz 500Hz
1kHz 2kHz 4kHz 12.5kHz
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Technics RS-TR979 Specifications

General

Brand	Technics
Model	RS-TR979
Category	Cassette Player
Language	English