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6. ADJUSTMENT
6.1 ADJUSTING THE MD SECTION
1) Precautions
Since the single voltage (3.3V) system is being employed for the regulator of this equipment, the reference potential
for the servo signals becomes Vc (1.65V, approximately).
In this manual, the Vc reference potential will be indicated as **Vc (e.g. 1.5Vc) and the reference GND will be indicat-
ed as **V.
If connection errors of the Vc and the GND are made while product adjustment is being made, it becomes unfeasible
to measure the electric potential correctly and, moreover, the servo can make malfunctioning to apply severe
impacts to the pick up. Consequently, to prevent occurrence of such an error, observe the followings.
1. Do not make connection errors of the Vc and the GND when connecting the negative side of the probe of the instru-
ment.
For example, do not connect the Vc to the negative side of the probe ch1 nor connect the GND to the negative side
of the probe ch2 of the oscilloscope.
Also, since the measuring instrument proper usually carries the same potential as that of the negative side of the
probe, in many cases, set the measuring instrument proper to a floated state.
2. When installing and removing the filters and wires necessary for the measurement work, always turn "OFF" the batt.
and Acc line. (Only when the regulator is turned off, the microcomputer is negatively occasionally affected.)*1
3. Since various protection means of the software are not valid under the test mode, be careful not to apply mechanical
shock and electric shocks while adjustment work is in progress.
4. This equipment works to discriminate the discs namely, high reflection discs (premaster) and low reflection discs
(recordable), when the discrimination SW is duly operated.
(High reflection Disc=0V and low reflection Disc=5V with the CN401 / 4-pin / Contact Pin Name: DISC as is shown in
the circuit diagram)
Disc discrimination can be confirmed by the following indications appearing under (the above octonary digits) the
TEST MD mode, after completing floating of the disc under the TEST mode.
In case of high refection: 02200000 In case of low refection: 01100000 (The second and third digits counting from
the Left-hand side will become "2" or "1".)
Unless disc discrimination is made properly, accurate automatic adjustment and grating adjustment cannot be
expected and always confirm the above when starting up the TEST mode.
2)LD protection for the pickup
Unlike MD pickups, the MD pickups being used for this equipment are not equipped with the LD protection short pin
but, instead, a shorting land by soldering is being provided.
When removing, make a shorting by soldering before removing the flex.
To protect the flex., limit the time to apply the soldering iron to a short time. Reference application time: within 2
seconds.
3)Regarding the TEST mode
This mode should be used when adjusting and inspecting the MD mechanism module of this equipment.
1. When entering into the TEST mode:
Pressing and holding the "4" key and "6" key simultaneously, turn ON the "B.u" and "Acc" at the same time.
Select the "MD Source" using the SOURCE key. (Keep the Disc inserted.)
2. When canceling the TEST mode:
Turn OFF the "B.u" and "Acc".
3. When turning ON the MD power
Press the key "BAND" to start up the 3.3v for the MD regulator.
Meanwhile, pay attention to the fact that the microcomputer supply power Vdd5v starts up when the "B.u" and
"Acc" are turned on.
4. Measuring LD electric current
When measuring the voltage between 3VD and VI using a multimeter or the like, be sure to connect the measuring
instrument on the power supply off before turning on the power supply.
If you make contact between 3VD and VI using a clip or the like after turning on the power supply, the noise could
cause LD failure.
*1 At "Batt. Line" is on and "Acc Line" is on , MD is off(regulator id off).
Power supply of MD mechanism for microcomputer : VDD is on.
Additionally , power supply for IC : MDVD and PVD are off.
MEH-P5350
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