Bias Trap Adjustment; Bias Current Pre-Adjustment; Erase Head Dummy Coil Adjustment - Sony CCP-1100SF Service Manual

4-2-5. Bias trap adjustment

Test equipment : Level meter
Adjustment point : FL1, FL2/AU-2 board
Procedure :
1. Set the SIDE selector to "A+B".
2. Activate the service mode. (Don't insert a cassette tape.)
3. Press the COPY button, connect the level meter to the
following test point on the AU-2 board.
4. Adjust the bias trap associated with the test point so
that the output becomes the minimum.
CH Level meter connection
+ + + + + terminal
CH-1 TP3
CH-2 TP4
AU-2 Board Component Side

4-2-6. Bias current pre-adjustment

Test equipment : Voltmeter
Adjustment point : CT1, CT2/AU-2 board
Procedure :
1. Active the service mode. (Don't insert a cassette tape.)
2. Press the COPY button, connect the voltmeter to the
following test points on the AU-2 board.
3. Adjust the trimmer capacitor associated with the test
point so that the output becomes 40 ± 3 mV
CH Voltmeter connection
+ + + + + terminal
CH-1 TP106
CH-2 TP107
AU-2 Board Component Side
CCP-1100SF
Adjustment
_ _ _ _ _ terminal point
E3 FL1
E4 FL2
E3
FL1
TP3
TP4
FL2
E4
Adjustment
_ _ _ _ _ terminal
point
E107 CT1
E107 CT2
TP107
TP106
E107
CT1 CT2

4-2-7. Erase head dummy coil adjustment

Note : Before this adjustment, the bias current pre-adjustment must has
been finished.
Test equipment : Voltmeter
Frequency counter
Coil (10 mH)
Adjustment point : L4/AU-2 board
Procedure :
1. Set the SIDE selector to "A+B".
2. Activate the service mode. (Don't insert a cassette tape.)
3. Press the COPY button.
4. Connect the voltmeter to test point TP106 on the AU-2
board. and measure the voltage.
Specification : 40 ± 3 mV
(If out of the specification, again adjust the bias
current pre-adjustment.)
5. Connect the coil to the frequency counter.
6. Make the coil approach to erase head to check that the
bias frequency is in specification.
Specification : 550 kHz ± 3 %
(If out of the specification, again adjust the bias
frequency.)
7. Next, set the SIDE selector to the "A", and measure
the voltage at the test point TP106.
Then, adjust the dummy coil L4 so that the difference
between the measured voltage and that when the SIDE
selector was in "A+B" status is within 3 mV in the
rang of 40 ± 3 mV.
8. Again, make the coil approach to the erase head, and
adjust the bias transformer so that difference between
the measured bias frequency and that when the SIDE
selector was in "A+B" status is within 16 kHz in the
range of 550 kHz ± 3 %.
Voltmeter Connection
+ + + + + terminal _ _ _ _ _ terminal
TP106 E107
AU-2 Board Component Side
Adjustment
point
L4
E107
TP106
L4
4-5