Sharp VC-90ET

VC-90ET
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ADJUSTMENT
OF
Hi-Fi/
LINER
AUDIO
CIRCUIT
e@ Test Points Layout
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EELEV ADL?
Figure 2-21.
(The items in brackets [ ] refer to R-CH parts.)
Adjustment of EE level
Measuring
[Mode ST EE(PAL) =
Specification
1. Turn the input selector switch to “AUX”.
2. Input—8dBs, 1kHz signal to audio input terminal.
3. Connect CH-1 of an VTVM to the left of the audio
output terminal, CH-2 to the right of the audio
output terminal and adjust R6313 [ R6311] so that
the reading of the VTVM becomes — 8dBs, 1kHz.
Note:
Both R6313 and R6311 are located on the opration
unit. Adjustment of deviation.
Adjustment of deviation
(Adjustment by using a spectrum-analyser)
[Mode
|
REC
(PAL)
Input
signal
—8dBs,
1kHz
Test point TP6309 [TP63 10]
TP6306 (GND)
Adjusting point R6362 [R6374] (deviation
control)
50 + SkHz
1. Feed - 8dBs, 1kHz signal to the audio input
terminal.
2. Observe TP6309 [TP6310] (Hi-Fi unit) and TP6306
(GND) signals by the spectrum-analyser, and adjust
R6362 [R6374] so that the spectrum-analyser reads
50 + 5kHz. (as shown in Figure 2-22)
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DEVIATION a?
TRS3C8
Hi-Fi PWB
41
5OKHz 50KHz
fo = 1.4MHz L-CH
fo = 1.8MHz R-CH
Figure 2-22.
(Adjustment by using a frequency counter and an
VTVM)
Frequency counter, VTVM
|Mode si Recording / Playback
Tape used Hi-Fi alignment tape
(VROCBFFS)
= BBs, kHz
Tast point TP6309 [TP6310]
TP6306 (GND)
Adjusting point R6362 [R6374)
Specification -8+1dBs
1. Play back the Hi-Fi alignment tape (VROCBFFS) and
check that the playback level is-—8 + 1dBs.
2. Check the carrier frequency: connect a frequency
counter to TP6309 [TP6310] and TP6306 (GND)
check that the reading is 1.4 MHz+10kHz
[1.8MHz + 10kHz].
3. Input — 8dBs, 1kHz signal to the audio line input
terminal.
4. Set the recording level control to the center click
position.
5. Record the signal and play it back. If the playback
level is less than — 8+1dBs, turn R6362 [R6374]
clockwise; if more than - 8+ 1dBs, turn it
counterclockwise. Record the signal and play it
back again.
6. Repeat Step 5 until you obtain a reading of - 8
dBs + 1dBs.