Sharp SD-EX100H (serv.man9) Service Manual ▷ View online
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SD-EX100H
TO CHECK AND CANCEL PROTECT CIRCUIT DETECTION LINE
1. After power supply, the microcomputer (ICD01) built in this
model consecutively monitors the following errors
1
to
4
.
If any error occurs, "Er_AP00" is displayed and all power
supply except for the one to drive the microcomputer is
interrupted.
supply except for the one to drive the microcomputer is
interrupted.
1
Abnormal output voltage drop of each regulator
(below approx. 3 V)
2
Excessive output offset of 1-bit amplifier
(over approx. 2 V of DC potential)
POWER OFF after "Err_AP02" displayed
POWER OFF after "Err_AP02" displayed
3
Excessive main supply current of 1-bit amplifier
(over DC approx. 5.5 A)
4
When 1 bit + BAMP voltage is over 23 V, "Err_AP03" is
displayed for POWER OFF. (Check during power ON.)
2. Criteria for judging errors of built-in microcomputer and
checking/cancelling detection line
Condition: Abnormalities are detected according to the
Condition: Abnormalities are detected according to the
voltage of Pin 91(PROTECT) of microcomputer.
Checking/Cancelling
Caution: When interrupting the PROTECT detection line,
the microcomputer does not operate protectively.
In case of an error caused by output short-circuit
of each regulator, components and board on the
spot may be burnt. Do not interrupt the PROTECT
detection line of the microcomputer, if any cause
other than the above mentioned is not identified.
(For approx. 0.5 seconds after error detection,
power is supplied; power supply can be checked
with an oscilloscope, etc. As leading and trailing
edges of the voltage are so steep that the power
supply cannot be checked by the tester.)
In case of an error caused by output short-circuit
of each regulator, components and board on the
spot may be burnt. Do not interrupt the PROTECT
detection line of the microcomputer, if any cause
other than the above mentioned is not identified.
(For approx. 0.5 seconds after error detection,
power is supplied; power supply can be checked
with an oscilloscope, etc. As leading and trailing
edges of the voltage are so steep that the power
supply cannot be checked by the tester.)
1
Abnormal output voltage drop of each regulator
Connect the measuring apparatus (oscilloscope, etc.) to
the stabilized output of the regulator to turn on the unit
power switch.
If the stabilized output is far smaller (below approx. 3 V)
than that shown in the circuit diagram, the regulator and
the circuit to be supplied with the power may be defective.
the stabilized output of the regulator to turn on the unit
power switch.
If the stabilized output is far smaller (below approx. 3 V)
than that shown in the circuit diagram, the regulator and
the circuit to be supplied with the power may be defective.
2
Excessive output offset of 1-bit amplifier
After disconnecting the BIA110 (speaker output connector
of 1-bit amplifier), turn on the unit power for the normal
operation. (No sound is heard from the speaker.)
of 1-bit amplifier), turn on the unit power for the normal
operation. (No sound is heard from the speaker.)
* After repair, adjust 1-bit amplifier output-offset voltage.
If protected operation is still observed after removal of
BIA110, circuits Q460 ~ Q463 (for detecting speaker
output DC voltage) may be abnormal.
output DC voltage) may be abnormal.
3
Excessive main supply current of 1-bit amplifier
After disconnecting the BIA111 (main power source
connector of 1-bit amplifier), turn on the unit power for the
normal operation. (No sound is heard from the speaker.)
connector of 1-bit amplifier), turn on the unit power for the
normal operation. (No sound is heard from the speaker.)
* After repair, adjust 1-bit amplifier output-offset voltage.
If protected operation is still observed after removal of
BIA111, circuits IC570 and IC571 (for detecting power
supply current) may be abnormal.
BIA111, circuits IC570 and IC571 (for detecting power
supply current) may be abnormal.
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