Dc Offset Error; Cd Load Error Detection - Kenwood DPX501 Service Manual

Purpose
Prevent customers' vehicle speakers damages, burnouts, and
smoking.
Avoid the connected speakers to be burned out, damaged, or
to smoke when DC occurs between the audio power amp. +
and - outputs.
Processing after detection
1. System status
• At the detection of DC error, error data is to be saved im-
mediately (E2PROM error log save area).
• Display the error message on the display. The system shall
maintain the current condition, including the operation. Shut
down audio system power supply. Set Mute to ON.
• Although switching between Power OFF and ON (ACC, BU,
and Key operation) is valid, switching from Off to ON shall
be error until the µ-com is reset.
∗ While power-on, even if the IC2VI DCErr output terminal
logic recovered to normal level value, the error condition
shall continue.
• Prohibit to save the backup/installer memory to E2PROM
(nonvolatile memory).
2. Controlling µ-com terminal
• Set Mute for all channels including for pre-out.
• Turn off power IC control system power supply. (Set AMP-
Standby function to valid)
• Set P-Con output to OFF (Logic by which external AMP
unit is turned off).
∗ The purpose is to shut down audio output. Basically, the
logic sets the audio output system signal line when in
Standby source.
Overview
Record the number of times when mechanism error (SW er-
ror) occurred at CD LOAD.
LOAD error recording shall be done in 2 patterns, by the SW
status illustrated below.
LOAD error is established when LOAD operation is not com-
pleted after LOAD operation is started before the protect timer
count is completed.

DC OFFSET ERROR

CD LOAD ERROR DETECTION

DPX501/501U/501UY
DPX-MP2090U
3. Key specification
• No specific limitation (Normal operation).
4. Display specification
• Display the "PROTECT" string and blink all characters at
1Hz.
∗ Use the indication below with the highest priority (error mes-
sage), and maintain the error message even when the
source is changed.
Display Example
( Blink alternately
at 1Hz
PROTECT
Cancel Condition
• Press the Reset terminal on the main body. or set Backup
to OFF (Unplug and plug back in the DC connector).
The history is maintained (E2PROM data is saved).
Note while in test mode
• While in test mode, even if DC leak is detected, it is not
written into E2PROM.
When an error is detected, the display is enabled.
Other
• Function for checking and clearing data in E2PROM by a
given key shall be included.
(Used at production dpt. and service center, etc.)
Clearing of record is done in the following situations:
1) After reset is cancelled, when reading EEPROM, the code
is NG.
2) While in test mode, the specified key (Play/Pause key
pressed for 2 seconds) input.
3) When in EEPROM all-clear initialization mode (refer to
the test mode specification document)
• Display is shown on the test mode specification document.
• Number of times with error(s) is 99 at MAX.
• Not recorded in test mode [1+3 keys].
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