Teac A-2300SD - Bias Trap Adjustment; Bias Leakage Check; Record Head Azimuth Adjustment; Bias Adjustment

9-15 BIAS TRAP ADJUSTMENT
1. Remove all input signals.
2. Set MONITOR switches to SOURCE and REC MODE
switches to ON.
3. Set REC BIAS switch to #1 position.
4. Load TEAC YTT-8013 test tape on the unit.
5. Connect a VTVM or oscillocope from ground to the
junction of L-401 and C-403 (L ch) and from ground
to the junction of L-403 and C-425 (R ch).
6. Adjust L-401 (L ch) and L-403 (R ch) for minimum
reading on scope or VTVM. Use non-inductive screw
driver.
FINE ADJUSTMENT
NOTE; it is absolutely essential to accomplish the
course adjustment before performing the fine
adj. to avoid phase errors greater than 45°.
6. Connect the test equipment as shown in figure 9-4.
7. Apply a 7.5 kHz signal at-18 dB to the LINE IN jacks
and record this signal.
8. Carefully adjust the azimuth screw until the oscillo¬
scope shows the signal to be in phase.
9. Secure the screw with insulating locking paint.
L40I/403
C403/425
^^ 0401/407
CHECK POINT
BIAS-OSC
O ^ REC HEAD
T-372
Fig. 9-9 Phase Shift
Fig. 9-8 Bias Trap Check Point
9-16 BIAS LEAKAGE CHECK
7. Change the MONITOR SW to TAPE position.
8. Adjust L-202/204 (on DOLBY DECODER PC Board)
for minimum bias leakage reading at OUTPUT jacks.
Spec. -40 dB or less.
9-18 BIAS ADJUSTMENT
1. Place REC BIAS switch to #1 and REC EQ switch
to#1.
2. Place MONITOR switch in the TAPE position.
3. Apply 7 kHz signal at—18 dB to the LINE IN jacks.
4. Adjust capacitor VC-20/21 for a peak reading on the
VTVM, then turn the capacitors clockwise until a
decrease of 2.5 dB from the peak is obtained.
9-17 RECORD HEAD AZIMUTH ADJUSTMENT
The following adjustments are made only at
3-3/4 ips (LOW) speed.
COURSE ADJUSTMENT
NOTE: The effect of turning the azimuth screw will
not immediately register on the VTVM. A
slight delay will be noticed. Therefore, the
screw must be rotated slightly with a pause
to see the effect.
1. Thread a record test tape YTT-8013 or equivalent
tape on the unit.
2. Connect a VTVM to the OUTPUT jack and an AF
oscillator to the LINE IN jack. Set the oscillator
to 5 kHz at—18 dB.
3. Place the MONITOR switches to TAPE position.
4. Begin recording (Depress REC and ► play bottons).
5. While recording adjust the azimuth screw for maximum
reading on the OUTPUT VTVM.
Peak
Fig. 9-10 Bias Limits Chart
9-19 REC EQ #1 LEVEL SET
1. Thread a record Test Tape TEAC YTT-8003 on the unit.
2. Apply a 400 Hz signal at —8 dB to the LINE IN jacks.
3. Place Tape SPEED SW to the 7-1/2 ips (HIGH) position.
4. Begin recording.
5. Adjust REC LEVEL CAL VR-5O2/505 (on the back
panel) for 0 dB at OUTPUT jacks.
17