Pioneer RX-P840 Service Manual page 12

RX-P840
FM/AM TUNER MODULE
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1. Handling Precautions
@ Since the heat sink and transistor metallic parts are
connected to the Front Amp output, make sure they do
2. Adjustment and Confirmation of Idle Current
@ Basically, the idle current needs to be confirmed when
replacing a power transistor, driver transistor, or bias
not contact the GND (chassis) or other circuits. transistor, or when the entire split board Assy of the
@ Since there is residual high voltage in the Power Amp Power Amp Module Assy has been replaced.
Module Assy +Bl (FRONT ASSY FOR 100W) even @ Make sure the heat sink has cooled sufficiently before
when the power is OFF, caution should be exercised. (If
measuring the idle current. (Temperature should be the
you do not touch the fan motor blade.
Mi Front Amp Side (FRONT ASSY FOR 100W)
Insert a resistor (0.22Q, 3W or more) in series in the connector For measuring voltage at both sides of
CN7502 +Bi (or —B1) line (terminal No. 5 or 6). (Refer to Fig. 2—2.) | resistor
Lch side Short both sides of C7524. Do not operate Rch side.
Turn the power ON, wait 6 seconds, and then measure the resistance
voltage in Step 1. Lch Idle current I=V_/0.22 (Q)
@ Same as Step 1 above. :
@ Short both sides of C7523.
Do not operate Lch side.
Rch side
Turn the power ON under the above conditions, and after 6 seconds
measure the resistance voltage in Step 1.
If the measured idle current is greater than 50mA, perform the
following procedure.
Lch side Short between the Point @) pattern in Fig. 2—3 using solder. pl R7517 to R7515 in a parallel
Rch side
Short between the Point ®) pattern in Fig. 2—3 using solder.
ied R7518 to R7516 in a parallel
After performing Steps 7 and 8, remeasure the idle current and
confirm that it is below 50mA.
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