Daewoo DVR-1989D - 2-4. AUDIO CIRCUIT ADJUSTMENT METHOD

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2-4. AUDIO CIRCUIT ADJUSTMENT METHOD

1. PLAYBACK OUTPUT LEVEL

1) Connect the audio level meter to the audio line output jack.

2) Play back the test tape.

3) Adjust RV291 until the audio level meter reads -5¡ 1.5dBs play back output.

2. PLAYBACK OUTPUT FREQUENCY CHARACTERISTIC

1) Playback the Test tape, and confirm that the playback output level at 7 KHz is within 0¡ 3 dB as referenced to the 1 KHz 1) 1)

playback output level.

3. BIAS CURRENT ADJUSTMENT AND OSCILLATION FREQUENCY CHECKING

1) Supply the signal in the OPEN mode

2) Conncet the positive lead of the VTVM to TP201 and negative lead to TP202.

3) Set the VCR in recording mode.

4) Confirm the frequency counter display is 70 KHz¡ 10% and adjust RV292 until VTVM reads 2.3 mVrms

4. RECORD-PLAYBACK FREQUENCY RESPONSE

1) Connect the audio signal generator to the audio line input jack, and the audio level meter to the audio line output jack

2) Record referene audio signal of the 400 Hz and 10 KHz (SP) audio signal at -20 dBs.

3) Check to insure that 10 KHz playbck output level is within -1¡ 3 dB as referenced to the 400 Hz playback output level.(SP)

4) If the difference between 10 KHz and 400 Hz playback output level is more than +1 dB, increase the bias current more than

4) 2.3mVms, and if the difference is less than -3 dB, reduce the bias current less than 2.3 mVrms.

5. RECORD-PLAYBACK OUTPUT LEVEL

1) Connect the audio signal generator to the audio line input jack.

2) Record and playback the input of the audio reference signal 1 KHz, -10 dBs.

3) Confirm that play output level is -5¡ 3dBs as referenced to the playback output level