Pioneer A-09 Manuale di servizio - Pagina 34

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6. ADJUSTMENTS

6.1 INITIAL ADJUSTMENT

6.1.1 Adjustment of DC Offset Voltage (Fig.1)

After having turned on the power, adjust VR301 and VR302 of

VOLTAGE

AMP

assembly

inside the rear

box

so that the

voltage between the speaker terminals

( + and

—) becomes

within +10mV.

6.1.2 Adjustment of the Idle Electric Current (Fig.2)

Adjust VR402 so that the voltage between the emitter resistors

(R460, R466) of POWER

R I/O assembly (between the idle

check terminals) becomes 170mV.

Note : When on the left side, adjust VR401

of POWER

L I/O

assembly. Also reverse the polarity of the voltage meter.

(9)

Reh (VR302)

Leh (VR301)

Rear side

Voltage meter

Fig. 1 DC offset voltage adjustment

Voltage meter

A-09

6.2 AGING

After having adjusted the initialization, carry out aging for 5

minutes.

6.3 FINAL ADJUSTMENT

1. Adjust the DC offset voltage to within £10mV with VR301

and VR302.

2. After this, carry out idle current adjustment of the voltage

value with VR401 and VR402 to 150mV

+5mV.

R side heat sink assy

Voltage meter

(Approx. 250mvV)

VR402

Fig. 2 Idle current adjustment