Adjustment - Kenwood X92-3770-00 Service Manual

X92-3770-00,0-01/X92-3780-00,0-01
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Service Test Mode (Manual Adjustment Mode) of the MDS-2200
The focusing bias (balance) adjustment of the MDS-2200 has been subjected to automatic adjustment at the factory and the
obtained bias value has been written in the E2PROM, and the set performs adjustment by reading the E2PROM data.
Consequently, after the pickup has been replaced in servicing, it is required to adjust the focusing bias again. This can be done
automatically if the dedicated commander for the MDS-2200 and a jitter meter are available, but the set also incorporates a
service test mode (manual adjustment mode) for use in case these instruments are not available.
• Adjustment procedure (Be sure to begin setup while the power of the set is off.)
1. Pull up pin 60 (LADJ1 (check land 1)) of lC11 in the X33-unit to BU5V (check land BU5).
2. Lead wires from check land ARF and check land SAG (servo GND) in the X33-unit so that they an be monitored with an
oscilloscope.
3. Turn the set on and perform the reset power-ON operation.
∗ The adjustment includes three modes ; the Iow-reflection pit and groove modes for recordable discs and the high-reflection
pit mode for premastered discs.
4. Load a disc to enter the adjustment mode.
<With a recordable disc>
5. The low-reflection pit play mode starts when TNo.1 is displayed.
The time code display shows "50".
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6. While monitoring ARF with an oscilloscope, vary the focusing bias using the Track UP and DOWN keys.
7. The optimum values can be obtained by varying the bias in the UP and DOWN directions, locating the upper and lower values
at which the ARF waveform is disturbed or the 3T waveform level drop, and calculating the center value of the two values.
For example, when the value located in the UP direction is 58 and that located in the DOWN direction is 46, the optimum value
is their center value, i. e. 52.
8. When the optimum value is obtained, set the focusing bias to that value and press the ManuaI UP or DOWN key to enter the
value.
(With normal sets, press and hold the Track UP or DOWN key.)
9. After the low-reflection pit adjustment in step 8, the pickup automatically moves to the groove area.
10. The groove play mode starts when TNo.2 is displayed.
11. Perform the same operations as steps 6, 7 and 8.
12. The disc stops after the groove area adjustment .
Eject the disc and complete adjustment.
∗ Since the low-reflection pits are present only in the TOC area, their total play time is about 40 seconds. When the pit area
is over, the retry operation starts and the adjustment is invalid in this period.
<With a premastered disc>
13. When the high-reflection play mode starts, perform operations in steps 5, 6, 7 and 8.
14. The disc stops after the adjustment. Eject the disc and complete adjustment.
∗ The coarse adjustment of the EF balance is also performed during this test mode.
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However, it is an automatic adjustment and does not require external poeration.
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ADJUSTMENT

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