Wednesday, October 06, 2021

Panasonic SA-AKX74LM CD stereo system - How to enter the service mode, self diagnostic, Demonstration lock, D-amp and SMPS schematic, Power board error codes

 

Always respect voltages. It makes sense to avoid exposure to electrical shock.  While some sources are expected to have a possible dangerous impact, others of quite high potential are of limited current and are sometimes held in less regard.

Before Repair

  Disconnect AC power to discharge unit AC Capacitors as such (C5700, C5701, C5703, C5708) through a 10 Ω, 10 W resistor to ground.  DO NOT SHORT-CIRCUIT DIRECTLY (with a screwdriver blade, for instance), as this may destroy solid state devices.
After repairs are completed, restore power gradually using a variac, to avoid over current.

Fuse type: 8A, 125 V

  When the protection circuitry functions, the unit will not operate unless the power is first turned off and then on again.

Protection Circuitry
The protection circuitry may have operated if either of the following conditions are noticed:
* No sound is heard when the power is turned on.
* Sound stops during a performance.
 The function of this circuitry is to prevent circuitry damage if, for example, the positive and negative speaker connection wires are “shorted”, or if speaker systems with an impedance less than the indicated rated impedance of the amplifier are used.
If this occurs, follow the procedure outlines below:
1. Turn off the power.
2. Determine the cause of the problem and correct it.
3. Turn on the power once again after one minute.

 This product utilizes a laser diode with the unit turned “ON”, invisible laser radiation is emitted from the pickup lens.
Wavelength: 790 nm (CD)
Maximum output radiation power from pickup: 100 PW/VDE
Laser radiation from the pickup unit is safety level, but be sure the followings:
1. Do not disassemble the pickup unit, since radiation from exposed laser diode is dangerous.
2. Do not adjust the variable resistor on the pickup unit. It was already adjusted.
3. Do not look at the focus lens using optical instruments like convex lens or similar oblects.
4. Recommend not to look at pickup lens for a long time.

 The lead free solder has been used in the mounting process of all electrical components on the printed circuit boards used for this equipment in considering the globally environmental conservation.
The normal solder is the alloy of tin (Sn) and lead (Pb). On the other hand, the lead free solder is the alloy mainly consists of tin (Sn), 96.5%, silver (Ag) 3.0%, Copper (Cu) 0.5%, Cobalt (Co) / Germanium (Ge) 0.1 to 0.3%  Use the soldering iron (more than 70W) equipped with the temperature control after setting the temperature at 350±30 degrees C (662±86qF).

This model uses CD Mechanism Unit (BRS11C).

Micro-processor IC, IC2003 (MN101EF16KXW)

This model uses Speaker System, SB-AKX54, SB-WAKX74LM-K.

Service Mode

Cold-Start
Here is the procedure to carry out cold-start or initialize to shipping mode.
1. Unplug AC power cord
2. Press & hold [POWER] button
3. Plug AC power cord while [POWER] button being pressed
FL Display will show “ -------------“
4. Release [POWER] button.

DOCTOR MODE



Self-Diagnostic Mode & Self-Diagnostic Error Code Table
Self-Diagnostic Function  provides information on any problems occurring for the unit and its respective components by displaying the error codes. These error code such as U**, H** and F** are stored in memory and held unless it is cleared.
The error code is automatically display after entering into self-diagnostic mode.

Power Supply Error Codes 

CD Mechanism Error Code Table (CD Mechanism Unit (BRS11C)

Sales Demonstration Lock Function
Entering into sales Demo Mode
Here is the procedures to enter into Sales Demonstration Lock.
Step 1: Turn on the unit.
Step 2: Select to any mode function.
Step 3: Press [ Eject OPEN/CLOSE] key then [ Play/Pause] key at the same time, press and hold both [ Eject OPEN/CLOSE] and [Play/Pause ] keys for 5 sec.
Step 4: The display will show upon entering into this mode for 2 sec..

Note: [Eject OPEN/CLOSE] button is invalid and the main unit displays “LOCKED” while the lock function mode is entered.

Cancellation
Step 1: Turn on the unit.
Step 2: Select to any mode function.
Step 3: Press [ Eject OPEN/CLOSE] key then [Play/Pause ] key at the same time, press and hold both [ Eject OPEN/CLOSE] and [Play/Pause] keys for 5 sec.
Step 4: The display will show upon entering into this mode for 2 sec.

Common faults and defective resistors positions

Main PCB

D-Amp PCB

D-Amp circuit diagram (Schematic)


Panel schematic


Sub-woofer circuit diagram

SMPS (Power Board schematic)





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