Pioneer 1014TX-K - THX Select A/V Receiver, Service Manual

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7. GENERAL INFORMATION
7.1 DIAGNOSIS
7.1.1 PROTECTION CIRCUIT CONTROL SPECIFICATION
Microcomputer-related ports
DC_PROT (pin 74 of IC501: MAIN CONTROL Assy)
Input port : For DC detection
OL_DET (pin 73 of IC501: MAIN CONTROL Assy)
Input port : To detect overloading at the amplifier
(Interrupt port)
FAN_STOP (pin 92 of IC501: MAIN CONTROL Assy)
Input port : To detect Fan forced stop
FAN_DRIVE (pin 91 of IC501: MAIN CONTROL Assy)
: For Fan on/off
TEMP2 (pin 44 of IC3001: DISPLAY Assy)
Input port : To detect temperature
12V_DET (pin 41 of IC3001: DISPLAY Assy)
Input port : To detect 12V trigger
The following control processes are activated immediately before
the relay system is turned on upon power-on. The time is 4.8
seconds after power-on. (Control of the relay system is enabled
5.2 seconds after power-on.)
Only DC detection is enabled 2 seconds after power-on to activate
it before other protection functions.
If this status continues for more than 3 seconds, the power is
turned off (for Standby mode).
Do not accept the key input afterward.
(Flash it always till turns the primary side off.)
If the port becomes "H" within 3 seconds, the unit resets
automatically.
DC_PROT port performs the chattering check for 1 msec.
In addition, there is the case that detection delays for maximum
20 msec because performs monitor of DC_PROT port with a main
loop.
Even if turns the primary side off and turns on once again.
If detects DC once and turned the power off, do not accept the key
input afterward.
However, power on is possible when the following key was
pressed to be able to key input in the protection line and service.
1. Test mode (remote control code : A55F)
2. When the STEREO/DIRECT key and SIGNAL SELECT key
are both held pressed for 2 seconds.
(Be effective when turned the power off by DC detection
regarding 2.)
2
Overload detection
(abnormality detection)
If the speaker terminals are short-circuited or low-load driving is
detected, the OL_DET port becomes "L"
Detecting "L" edge interrupt in an interrupt process, the
microcomputer performs the following operations:
1. System muting on
2. Speaker relay off (Control with the display microcomputer)
3. Power off (Standby mode)
1
DC detection (defect detection)
Only DC detection is enabled 2 seconds after power-on.
If there is a fault in the power amplifier or a high-level signal
lower than5 Hz is input, the DC_PROT port becomes "L"
Detecting "L" the microcomputer performs the following
operations:
1. System muting on
2. Speaker relay off (Control with the display microcomputer)
The warning indication "AMP ERR" appears on the FL display.
Protection Process List
Item Detection Method Process Warning Indication Remarks
DC detection Detects when the DC_PROT port
becomes "L".
Turns muting on and speaker
relay off, then turns off the
power after 3 seconds.
Flashing "AMP ERR" for 3
seconds.
If the power is turned off, flashes the MCACC
LED.
Do not accept the POWER key.
If the DC_DET port becomes "H" within 3
seconds, the unit resets automatically.
Overload
detection Detects when the OL_DET port
becomes "L" (checks by interrupt).
Turns muting on and speaker
relay off, and immediately
turns off the power.
None
Thermal shut
down
Detects when the TEMP2 port
becomes "H".
Turns muting on and speaker
relay off, then turns off the
power after 3 seconds.
Flashing "OVERHEST"
for 3 seconds
If the TEMP2 port becomes "L" within 3
seconds, the unit resets automatically.
After the power off, the key input is possible
once again.
12V trigger
short detection
Detects when the 12V_DET port
becomes "H".
Turns 12V_TRG port to "L",
then turns off the the 12V
output.
Flashing "12V TRI ERR"
Only a fan that is assigned 12V TRIG is
valid.
Release the FL indication with the power
on/off.