AIWA XRMK25 HCHR
Manual de Servicio

2. Tracking Balance Adjustment
Oscilloscope (DC range)

Symptoms

Gain

(Focus)

Tracking

4) Adjust SFR703 so that the waveform appears as shown in the figure below. (tracking gain adjustment)

High tracking gain (The frequency of the fundamental wave is higher than in low gain.)

TP3 (TB) TP2 (VC)

+

� The time until music starts becomes longer for STOP PLAY or automatic selection ( , buttons pressed.) (Normally takes about 2 seconds.) � Music does not start and disc continues to rotate for STOP PLAY or automatic selection ( , buttons pressed.) � Disc stops to rotate shortly after STOP PLAY. � Sound is interrupted during PLAY, or time counter display stops. � More noises during the 2-axis device operation.

low

low or high VC(VREF) 0V VC(VREF) 0V

-

�

low

1) Connect an oscilloscope to the test points TP3 (TB ) and TP2 (VC). 2) Turn on the power switch. 3) Insert test disc TCD�782 and press the PLAY button. 4) Connect the center point of SFR703 to TP2 (VC). 5) Adjust SFR702 so that the waveform on the oscilloscope is vertically symmetrical as shown in the figure below. 6) After the adjustment is completed, remove the connected lead wires from the terminals.

VOLT/DIV: 0.1 V TIME/DIV: 1 mS

VOLT/DIV: 0.1 V TIME/DIV: 1 mS

low or high

�

�

Incorrect example Low tracking gain (The fundamental wave appears as compared with the waveform adjusted)

�

low

high

high VC(VREF) 0V

A 0V VC(VREF) B

The following is a simple adjustment method. � Simple adjustment � Note : Since exact adjustment cannot be performed, remember the position of the control before performing the adjustment. If the position after the simple adjustment is only a little different, return the control to the original position. VOLT/DIV: 0.1 V TIME/DIV: 1 mS

A=B VOLT / DIV: 0.2V TIME / DIV: 1mS

Procedure : 3. Tracking Gain Adjustment A servo analyzer is necessary in order to perform this adjustment exactly. However, this gain has a margin, so even if it is slightly off, there is no problem. Therefore, do not perform this adjustment. Focus/tracking gain determines the pick-up follow-up (vertical and horizontal) relative to mechanical noise and mechanical shock when 2-axis device operates. However, as these reciprocate, the adjustment is at the point where both are satisfied. � When gain is raised, the noise increases when the 2�axis device operates increases. When gain is lowered, it is more susceptible to mechanical shock and skipping occurs more easily. When the gain adjustment is off, the symptoms below appear. 1) Keep the set horizontal. (If the set is not kept horizontally, this adjustment cannot be performed due to the gravity against the 2�axis device.) 2) Insert test disc TCD�782 and play back the second composition. 3) Connect an oscilloscope to TP3 (TB) and TP2 (VC).
Oscilloscope (DC range)

TP3 (TB) TP2 (VC)

+

-

�

57

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