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3)
Playback the TCW-231 test tape and check the output level if it is -10 dBV (0.3 V) ± 1 dB reading.
4)
If the reading is not within the above range, adjust R106 ~ R406 on the R/P AMP PCB assy.
3-9. Playback Frequency Response Calibration
1)
Set the controls as follows.
Record track select switch: OFF
Dolby B noise reduction on/off switch: OFF
2)
Connect an AC volt meter to the TAPE OUT 1 through 4 pin jacks respectively.
3)
Playback the TCW-284F test tape and adjust R103 ~ R403 so that the output level at 6.3 kHz is 0.5 dB lower than
the 400 Hz output level.
4)
Confirm that the output level at 12.5 kHz is within ± 1 dB of the 400 Hz output level.
3-10. Erase Current Adjustment
At adjusting the erase current, put a blank cassette tape to the transport and the track to be adjusted is put in REC mode.
Assuming the track 1 to be adjusted, the oscilloscope probe is connected to the test point TP106 on the R/P PCB assy
and rotate and fix the core T101 for minimum voltage point. Then, confirm that the voltage at TP105 is more than 55 mV.
NOTE:
If the voltage at TP106 is adjusted at minimum, the erase current flowing the erase head is set to the maximum.
Adjust the remaining tracks in the same way.
Track 2:
Adjust T201 for minimum voltage at TP206. Then, confirm that the voltage at TP205 is more than 55 mV.
Track 3:
Adjust T301 for minimum voltage at TP306. Then, confirm that the voltage at TP305 is more than 55 mV.
Track 4:
Adjust T401 for minimum voltage at TP406. Then, confirm that the voltage at TP405 is more than 55 mV.
3-11. Coarse Bias Adjustment
At coarsely adjusting the bias current, put a blank cassette tape to the transport and the track to be adjusted is put
in REC mode. Assuming the track 1 to be adjusted, the oscilloscope probe is connected to the test point TP104 on
the R/P PCB assy and rotate and fix the pot R133 (220 k ) at 60 mV.
Adjust the remaining tracks in the same way.
Track 2:
Adjust R233 so that the voltage at TP204 is 60 mV.
Track 3:
Adjust R333 so that the voltage at TP304 is 60 mV.
Track 4:
Adjust R433 so that the voltage at TP404 is 60 mV.
3-12. Record Level Calibration
*
The procedures up to 3-10 must be completed before proceeding to this adjustment.
1)
Put a blank cassette tape to the transport and apply a 400 Hz, -10 dBV (0.3 V) sine wave signal to the INPUT 1 and
2 phone jacks. (In the case the signal is input from XLR jack, the terminal No.3 (COLD) and No. 1 (GND) must be
shortened.)
2)
Set the controls as follows.
Record track select switch: All tracks ON (Confirm that the REC TRK LEDs (1 ~ 4) are blinking.)
Trim knob: At minimum
Dolby B noise reduction on/off switch: OFF
3)
Connect an AC volt meter to the TAPE OUT 1 ~ 4 pin jacks.
4)
Put the transport into REC PAUSE mode and adjust the Input Fader so that the level at TAPE OUT 1 ~ 4 is -10 dBV
(0.3 V).
5)
Release the PAUSE button and start recording the signal.
6)
After recording a certain length, rewind the tape to the start point of recording section. Then, playback the tape and
check the level at TAPE OUT 1 ~ 4. If the AC volt meter reading is not within -10 dBV (0.3 V) ± 0.5 dB, adjust the
pot R121 ~ 421 (22 k ) on the R/P PCB assy.
X-24
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