PIONEER HTZ7 I
Manual de Servicio

HTZ-7, HTZ-C7, HTZ-SW7

7.2 DIAGNOSIS
7.2.1 FAIL-SAFE DVD Center Unit (HTZ-C7)
1. System Reset after Detection Check of the power supply line (3.3 V line) (AD3: Pin 32)
Fail-safe for prevention of crashing of the DVD microcomputer (system controller) with occurrence of power supply ripples. (ADC read value for the power supply voltage of the player section at the time of power ON) System reset is applied when the threshold value is not reached six times in a row during power ON. Operation explanation The power supplied to the DVD assembly is composed of the three types +12 V, +5 V, and +3.3 V, and of these, the 3.3 V system is detected at all times. In the following diagram, dropping of the +3.3 V system to 3 V or less because of power supply trouble is detected, and the power supply is switched off.
Trouble (sag etc.) occurrence 3.3V 0.3V Power OFF and rapid drop
�12V (M)

The microcomputer at all times monitors pin §, and when this becomes low level, forced entry into standby mode is performed and the power supply of the set is switched off.
+5V +12V (M) FAN R5584 Q5513 R5586 R5585 D5509 R5587 Q5512 R5575 31 IC5501 µ-com

R5056 R5053

Fan Detection Circuit

Communication error with the DVD system controller
A system reset is applied when serial communication with the DVD system controller fails 32 times in a row.

2. Stop Mode after Detection (The appearance is a simple system reset.) Check of the AV control power supply line (5.6 [V] line) from the powered subwoofer unit (AD1: Pin 30)
When the power supply for the AV controller drops off, the AV controller enters stop mode and memory backup is performed. When the ADC read value for the power supply voltage twice in a row drops below the threshold value, stop mode (power saving mode) is entered and the memory contents are backed up.

Powered subwoofer (HTZ-SW7)
Power ON Power OFF

3.3 V system Trouble Detection

1. Power OFF after Detection DVD center display communication interruption
Power OFF is performed when the REQ edge of the DVD center display communication is interrupted for 1.5 sec. (The count value of the internal 1 ms timer is used for the judgment.)

Check of the power supply line (5 V line) (AD6: Pin 35)
Fail-safe at the time of disconnection from the power outlet. As the power for the AV controller is supplied from the powered subwoofer section, this kind of fail-safe becomes necessary. A system reset is applied when the ADC read value for the power supply voltage of the DVD center unit twice in a row drops below the threshold value.

Overcurrent detection
Power OFF is performed when the overcurrent detection port (always �H� while the power is ON) becomes �L�. (Judgment is performed once with the main loop.)

Abnormal temperature detection Cooling fan trouble detection (AD2: Pin 31)
When the cooling fan stops to run because of a defect, entry of foreign matter, etc. and energization is continued, there is the possibility of burning, so that a circuit for detection of this condition is included. A system reset is applied when the ADC read value for the cooling fan operation detection port twice in a row drops below the threshold value. Operation explanation When the fan is operating in the fan detection circuit, a current flows, so that a potential difference occurs at R5056 and Q5515 becomes ON. In this case, the anode potential of D5509 is � (minus), so that the potential becomes a reverse maximum voltage and D5509 does not open. Accordingly, Q5512 is OFF and pin 3 of the microcomputer reaches high level. When the fan rotation stops, Q5513 becomes OFF and the potential at C becomes +. Then D5509 becomes ON, and as the result, Q5512 becomes ON. Then pin § of the microcomputer becomes low level. An abnormal temperature is judged to exist when one of the abnormal temperature detection ports (A/D input, 2 ports) becomes 4.3 V or higher, and then the power is switched off. (Judgment is performed once with the main loop.)

Overvoltage detection
An overvoltage is judged to exist when the overvoltage detection port (A/D input port) drops to 3.5 V or less, and then the power is switched off. (Judgment is performed once with the main loop.)

2. System Reset after Detection Abnormal AC pulse
When the AC pulses have been interrupted for 2 pulses, reset start is performed. (Judgment is performed once with the main loop.)

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