XW-HTD640
60
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E
In a case of emergency, if XPROTECT becomes "L" or SP PROTECT becomes "H," Q3453 and Q3454 are turned on, and REF 5V
becomes nearly 0 V, which turns Q63 and Q54 off. Because this sets the voltage at gates Q62 and Q81 of the FET to 0 V, neither a PRE
+12 V nor a PRE +5 V signal is output, which shuts off the power supply to the POWER IC and the MAIN ASSY, and the progress of the
emergency status is stopped. As the protection function is not controlled by a microcomputer, when the power is turned on after a failed
circuit is repaired, the protection function is not reactivated.
was just shut off. When diagnosing, you can differentiate protection status from power-off status by checking if +8 V power to the FET
in the AMP module is on or not.
Protection Circuit
PROTECT operation
AMP PROTECT
Abnormal "L"
DC DETECT
Abnormal "H"
R67
VPRE+5
UPRE+5
REF5V
V+5
Q3462
R65
Q62
Q63
Q81
R56
R55
D81
D91
Q54
Q3453
Q3454
R3458
B
MAIN ASSY
I
REGULATOR ASSY
H
AMP ASSY
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