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MEH-P7100R,P7150

Grating adjustment

1) Regarding the TEST Disc

When performing grating adjustment and grating confirmations, use the high reflection Disc (MMD-110).
When confirming the operation state and automatic adjustment state, us the high reflection Disc (MMD-110) and low
reflection Disc (MMD-212), respectively.

2) When the pickup unit or the spindle motor has been replaced, be sure to perform the grading adjust-

ment and grating confirmation.

3) Grating adjustment

Purpose: To check and confirm if the grating is properly adjusted after the pickup unit or the spindle motor has been
replaced.
Observe the waveforms of “E” and “F” after having been passed through the iv amplifier L.P.F. using an oscilloscope
(X-Y ch) to check if the phase difference is within 30 deg. and, otherwise, to adjust it within the range.
Failure phenomena when the grating is being deviated substantially:
Tracking close becomes unworkable, tracking search becomes inoperable or tracking search takes too long time.
Checking method
Measuring instruments: Oscilloscope , GGD1223(21Pin cord) and GGF1370(MD adjustment PCB)
Measuring points: E. F and Vc
TEST Disc: MMD-110 (TEAC), TEST mode Focus closed state (Tracking open)

4) Confirmation procedures

1. Select the “MD Source” to inter into the TEST MD mode. Use the MMD-110 as the test Disc. An indication read-
ing “POWER ON” will appear.
2. Make the key operation of 2 -> 2 -> 1 -> 1 to bring into the focus close state. The indication will be “2221 0000”
and the pickup will be located at the inner-most position.

Key operation

Indications

Statuses

BAND

"POWER ON"

MD circuit 3.3v power “ON”

"0220 0000"

Disc discrimination (High reflection)

"0221 0000"

Offset adjustment

"1221 0000"

LD on

"2221 0000"

Focus close

<When the pickup has been replaced>

Re-adjust when the grating deviation exceeds 30 deg. (Refer to the drawing indicated below.)

1. Slightly loosen the screws <2> and <3> for the spindle motor (do not touch the screw <1>) and, inserting a minus

screwdriver head into the groove, turn it slowly checking the Lissajous’s figure.
When doing this, be careful not to insert the screwdriver head too deeply since it may hit the Disc surface.

2. After finishing the adjustment, tighten the screws <2> and <3> in given order.
3. Check the Lissajous’s figure once again.
* While making this adjustment, if the waveform disappears by some sock, repeat the key operation in the order of 1 -

> 1 (starting from the “LD on” process) and the waveform appears again.
If the above key operation procedures do not work to restore the state, press the key BAND (POWER OFF) -> press
the key BAND (POWER ON) to enter into the TEST MD mode once again before repeating the aforementioned proce-
dures once again in given sequence.

<When the spindle motor has been replaced>

Re-adjust when the grating deviation exceeds 30 deg. (Refer to the drawing indicated below.)
1. Loosen the screws <1>, <2> and <3> for the spindle motor in given order.
2. Re-adjust when the grating deviation exceeds 30 deg.
3. Follow the aforementioned procedures <when the pickup has been replaced> starting from the procedure according

to Paragraph 1 in given sequence.

* When the eccentricity of the disc is excessive, the grating waveform starts swinging. (It differs depending on the

rotation cycle.)
When it is difficult to make the adjustment, re-load the disc to decrease the eccentricity to lessen the swing before
reading the average phase difference.