PIONEER XVHTD540
Service Manual

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4 Protectiongenerated at the output because of a DVD PRTECT error high temperature is detected When DC is circuit that activates against 5 When abnormally a failure in the AMP system, etc. by the thermistor
6 The DVDM monitors the voltage of the main power supply by VDET signals. In Normal mode, the VDET signal is at the MID level (3.3 V). In the following conditions, the VDET signal level becomes Lcircuit the 5 -1 IC81 abnormal temperature detection or H, and microcomputer is notified of this abnormality. D AF Assy C 6CH AMP
VD+5 R3605 (R3625) (R3615) Front L ch V+12 27k (SW, SL) Front R ch 10k (C, SR) 10k 4.7k R3606 (R3626) (R3616) 27k +5V Q3632
E

Assy

VD+5

A

R108 27k

IC81

TH111

A

DVDM Assy

D
A

AF Assy NCP18WF104J03RB
R113 220 R112 1k Q111 2SC4081

to XPROTECT

V+5 47k +

V+12 Q3638 0 10k

B

VPR+8 47k C Q923 Q3633 Q922

XPROTECT V+12 Q921 D922 R111 1k

R3638 Q924 C3632 10k 470/6.3

Q3637

The voltage at Point A becomes the divided voltage of TH111 and R111//R112 (combined resistance of parallel-connected � In Normal mode, both Q3637 and Q3638 are off. V+12 470 470resistors R111 and R112.) In Normal mode, the resistance at TH111 is much higher than R111//R112, and Q111 is off. (Note VDET (1) When positive (+) V+5 voltage is generated at the SP V+6 DC 10k Q925 that the resistance at TH111 becomes lower as the temperature 17 terminal Q926 µcom D921 increases.) If the solder temperature at IC81 increases abnormally, 1M 0.1 0.01 When positive (+) DC voltage is generated at the L or R channel, UDZS4.7B 10k 47k the temperature at TH111 (thermistor) mounted closest to the land and VB of Q3637 becomes higher than that at the operation point, of IC81 increases accordingly, and the resistance at TH111 Q3632 (E, C, B) is turned on, and the level of XPROTECT decreases. becomes low. When the temperature at TH111 reaches 90-110_C (varying � The microcomputer detects the XPROTECT level and shuts according to conditions,) the voltage at Point (A) becomes high Itemsthe power to the unit off. to be detected by VDET enough to turn Q111 on, and the level of the XPROTECT line (1) When the power voltages inside the DVDM become abnormal, as shown in the table below becomes low. The microcomputer detects the XPROTECT level (2) When negative (-) DC voltage was generated at the SP and shuts the power to the unit off. terminal Operation Status XPROTECT is Power Voltage VDET voltage Q3638 is turned on, and activated.
V+3R3

B

Q923 off

Q924

Q922

Q921

D921

D922

Q926

Q925

C

In Normal mode VDVD+12 <1V >15.5V VPR+8 When an abnormality is generat V+6 V+5 >6.6V V+3R3 <2.5V >4.25V <5.2V >12.6V <3V <3.6V

off -2 D22 abnormal temperatureoff 5 off off off off detection circuit off Mid (on)

(on) off � � � � � � �

If the solder temperature at D22 becomes abnormally high (on) (off) off on off off L because of short-circuiting between AC - and +, or AC - and -, this off protection circuit is activated. off off off off on on L
off on
D22

off on � off on � �

off on � off on � �

off

�

on off

on off on on to
XPROTECT

L H L L H L H
D

on VFL+5 � � off A on
R131 � 560 1% (on)

� off on � �

�TH131 on NCP18WF104J03RB �
R133 220 � R132 � 680 1% �

on off � �

Q131 off 2SC4081

� �

(2) When the VDET signal to the microcomputer is interrupted because of defective soldering A becomes the divided voltage of TH131 The voltage at Point of the 30-pin connector or incomplete insertion of FFC and R131//R132 (combined resistance of parallel-connected � The VDET level is lowered by the pull-down resistor (1 Mohms) on the side of the microcomputer. resistors R131 and R132.) In Normal mode, the resistance at TH131 is much higher than R131//R132, and Q131 is off. (Note that the resistance at TH131 becomes lower as the temperature increases.) If the solder temperature at D22 increases abnormally, the temperature at TH131 (thermistor) mounted closest to the land of D22 increases accordingly, and the resistance at TH131 decreases. When the temperature at TH131 reaches 107-125_C (varying according to conditions,) the voltage at Point (A) becomes high enough to turn Q131 on, and the level of the XPROTECT line becomes low. The microcomputer detects the XPROTECT level and shuts the power to the unit off.

E

F

XV-HTD540
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