LG CM4650 Mini Hi-Fi System SMPS and power amplifier schematic, repair procedure, hidden key modes and more

MODELS: LGCM4650, (LGCM4650, LGCMS4750F)

1) The pick-up incorporates a strong magnet, and so should never be brought close to magnetic materials.
2) The pick-up should always be handled correctly and carefully, taking care to avoid external pressure and impact. If it is subjected to strong pressure or impact, the result may be an operational malfunction and/or damage to the printed-circuit board.
3) Each and every pick-up is already individually adjusted to a high degree of precision, and for that reason the adjustment point and installation screws should absolutely never be touched.
4) Laser beams may damage the eyes.  Absolutely never permit laser beams to enter the eyes. NEVER switch ON the power to the laser output part (lens, etc.) of the pick-up if it is damaged.

If there is dust on the lens surface, the dust should be cleaned away by using an air bush (such as used for camera lens). The lens is held by a delicate spring. When cleaning the lens surface, therefore, a cotton swab should be used, taking care not to distort lens.

Never attempt to disassemble the pick-up.
Spring has excess pressure. If the lens is extremely dirty, apply isopropyl alcohol to the cotton swab.
(Do not use any other liquid cleaners, because they will damage the lens.) Take care not to use too much of this alcohol on the swab, and do not allow the alcohol to get inside the pick-up.  Before replacing a component part, first disconnect the power supply lead wire from the unit
2) All equipment, measuring instruments and tools must be grounded.
3) The workbench should be covered with a conductive sheet and grounded.
When removing the laser pick-up from its conductive bag, do not place the pick-up on the bag. (This is because there is the possibility of damage by static electricity.)
4) To prevent AC leakage, the metal part of the soldering iron should be grounded.
5) Workers should be grounded by an armband (1 MW)
6) Care should be taken not to permit the laser pick-up to come in contact with clothing, in order to prevent static electricity changes in the clothing to escape from the armband.
7) The laser beam from the pick-up should NEVER be directly facing the eyes or bare skin.

Do not remove a replacement ESD device from its protective package until immediately before you are ready to install it. (Most replacement ESD devices are packaged with leads electrically shorted together by conductive foam, aluminum foil or comparable conductive materials).
7. Immediately before removing the protective material from the leads of a replacement ESD device, touch the protective material to the chassis or circuit assembly into which the device will by installed.

HIDDEN KEY MODE

Push both Front key and RCU key to activate it for 5 seconds.
1. Disc Lock On/Off (CD Function Only Active)
 Front Key : STOP
 RCU Key : STOP
2. Check Version and Option code
 Front Key : STOP
 RCU Key : PLAY/PAUSE
 You can change [Audio MCU Version <-> CD Controller Version <-> EEPROM Option] by SKIP+/-.
3. Clear EEPROM
 Front Key : STOP
 RCU Key : SKIP-

4. Edit EEPROM
 Front Key : STOP

RCU Key : SKIP+
 You can change the digit of option by SKIP+/-.
 You can edit 0~f by REPEAT or PLAY/PAUSE key.
5. Bluetooth DUT
 Front Key : STOP
 RCU Key : PROGRAM
 Bluetooth model only
6. Power Disc Lock On/Off (CD Function Only Active)
 Front Key : STOP
 RCU Key : EQ

7. Amp Clip On/Off
 Front Key : STOP
 RCU Key : Mute
Amp Clip Mode Change (Amp Clip On --> Amp Clip Off --> Level Down display)

SERVICE INFORMATION FOR EEPROM

POWER ON

FLD no disc status or AUX status

Remote control ‘Fwd skip’ + Front ‘STOP’ push same timing during 5 seconds

FLD ‘OP-0…

Move to appropriate position and make changes with remote control ‘skip, mode, play’ key

Press ENTER key

FLD ‘write ok

Remote control ‘Fwd skip’ + Front ‘STOP’ push same timing

FLD ‘E2P CLR

Completed.

Program download & update

MCS PROGRAM

Download program file name must be - HG520_FW_CM4750_DATE.bin
If security program (Water Wall) is activated on your PC, you must save the file to the USB storage device and disable the security software, then download the file to your set.
Caution: When downloading the file, you should neither unplug the USB device, change to the other function, nor power off the device. USB device must be unplugged when the downloading process is completed

On VFD display screen

EQ PROGRAM
Download program file name must be EQ_PRG_CM4750_***.BIN
If security program (Water Wall) is activated on your PC, you must save the file to the USB storage device and disable the security software, then download the file to your set.
Caution: When downloading the file, you should neither unplug the USB device, change to the other function, nor power off the device. USB device must be unplugged when the downloading process is completed

On VFD display screen

Repair help

NO POWER
If the unit doesn’t work by no power problem, repair the set according to the following guide.
FUSE & BRIDGE DIODE
check and replace F901, BD901, TH901 or TH903 on SMPS board.
How to troubleshoot (Countermeasure)
1) Check if the fuse F901 is open or short-circuit.
2) Check if the bridge diode BD901 is short-circuit by over current with a digital multi meter.
3) Check if the NTC thermistor TH901 or TH903 is normal or open.

If the unit doesn’t work by no power problem, repair the set according to the following guide.
D951
check and replace D951 on SMPS board.
How to troubleshoot (Countermeasure)
1) Check the anode-cathode voltage of D951 with a digital multi-meter, it is normally 0.2 ~ 0.3 V.   If it doesn’t have any voltage, it’s destroyed. Replace it with a new one.

NO BOOTING WHEN POWER ON THE SET
The set doesn’t work when press the power button on the front board or the remote control.
FLASH MEMORY
Check and replace IC503 on MAIN board.
How to troubleshoot (Countermeasure)
1) Check 5.6 V to CN501 in standby mode.   If there is no 5.6 V, check the SMPS.
2) Check 12 V, F+, F- and PVDD when power on the set.  - If the set doesn’t work regardless of what the KEY1 changes high to low while pressing the power button.
X500 and X501 work normally but, if you can not power on the set, replace IC501 with a new one on the MAIN board.

VFD is not displayed when power on the set
When power on the set, any icons or characters on VFD are not displayed.
check and replace DIG302 on FRONT board.
How to troubleshoot (Countermeasure)
1) Check if VKK, FL+ and FL- are output from SMPS to VFD via the MAIN board.
2) Check if IC501 outputs VFD_D0, VFD_CLK and VFD_STB to the FRONT board.
3) Check the GR signal (pulse signal) of IC408 on the FRONT board.
Check the SG signal (pulse signal) of IC408 on the FRONT board.
 If the GR and SG signal isn’t output, replace IC408 with a new one.  If the GR and SG signal is output, replace DIG302 with a new one.

NO OPERATION OF MD
When no sound output in the CD function, you can not listen to music reading data from a CD disc if the servo motors in MD don’t work. This step is for checking the SPINDLE MOTOR among them.
check and replace IC407, IC408 on MAIN board.
 How to troubleshoot (Countermeasure)
1) Check the SPDO signal from pin24 of IC407.  If no signal, check 3.3 V(RF) and X400.
2) Check the SPIN- & SPIN+ from IC408 to CN405 for driving SPINDLE motor. It is about 3.6 Vp-p. If no signal, check +1.8 V and +5 V for IC408.
3) Check if the FFC cable is solidly connected between CN405 and MD.
4) Check the MD. If the spindle motor is sort-circuit or has any trouble, it can not rotate CD discs.
check the function after changing another MD.

NO OPERATION OF MD
When no sound output in the CD function, you can not listen to music reading data from a CD disc if the servo motors in MD don’t work. This step is for checking the SLED MOTOR among them.
check and replace IC407, IC408 on MAIN board.
 How to troubleshoot (Countermeasure)
1) Check the SLDO signal from Pin23 of IC407.  If no signal, check 3.3 V(RF) and X400.
2) Check the SLED+ & SLED- from IC408 to CN405 for driving SPINDLE motor. It is about 2.9 Vp-p. If no signal, check +1.8 V and +5 V for IC408.
3) Check if the FFC cable is solidly connected between CN405 and MD.
4) Check the MD. If the sled motor is sort-circuit or has any trouble, it can not move the pickup module.
check the function after changing another MD

NO OPERATION OF MD
When no sound output in the CD function, you can not listen to music reading data from a CD disc if the servo motors in MD don’t work. This step is for checking the TRAY OPEN / CLOSE MOTOR among them.
 TRAY OPEN / CLOSE MOTOR
check and replace IC407, IC408 on MAIN board.
How to troubleshoot (Countermeasure)
1) Check MOT_OPEN & MOT_CLOSE signals from Pin K4, L4 of IC501 to IC408.  If no signal, check +1.8 V & + 5 V to IC408.
2) Check LOAD± from IC408 to CN405 for driving the tray open / close motor. It is about 3.85 Vp-p. If no signal, check +5 V to IC408. If it has any trouble, replace it with a new one.
3) Check if the FFC cable is solidly connected between CN405 and MD.
4) Check the MD.  If the tray motor is sort-circuit or has any trouble, it can not open or close the tray.
check the function after changing another MD.

NO OPERATION OF MD
When no sound output in the CD function, you can not listen to music reading data from a CD disc if the pickup module in MD doesn’t work. This step is for checking the LASER TRACKING ACTUATOR.
check and replace IC407, IC408 on MAIN board.
How to troubleshoot (Countermeasure)
The tracking actuator makes the laser beam be positioned in the center of a track on CD disc.
1) Check the TRD signal from Pin22 of IC407.  If no signal, check 3.3 V(RF) and X400.
2) Check TR- & TR+ from IC408 to CN408 for driving the tracking actuator.  If no signal, check +1.8 V and +5 V for IC408.

3) Check if the FFC cable is solidly connected between CN405 and MD.
4) Check the MD. If the pickup module has any trouble, it can not move the laser beam on the left or right side.
check the function after changing another MD.

NO OPERATION OF MD
When no sound output in the CD function, you can not listen to music reading data from a CD disc if the pickup module in MD doesn’t work. This step is for checking the LASER FOCUSING ACTUATOR.
check and replace IC407, IC408 on MAIN board.
How to troubleshoot (Countermeasure)
The focusing actuator makes the laser beam keep a regular interval with the surface of a CD disc.
1) Check the FOD signal from Pin21 of IC407.  If no signal, check 3.3 V(RF) and X400.
2) Check F- & F+ from IC408 to CN405 for driving the focusing actuator.  If no signal, check +1.8 V and +5 V for IC408.
3) Check if the FFC cable is solidly connected between CN405 and MD.
4) Check the MD. If the pickup module has any trouble, it can not move the laser beam on the top or bottom side.
check the function after changing another MD.

NO SOUND
There is no sound output in the CD FUNCTION, repair the set according to the following guide.
IN THE CD FUNCTION
check and replace IC501, IC601 on MAIN board.
How to troubleshoot (Countermeasure)
1) Check CD_BCLK, CD_LRCK, & CD_DOUTA signals from IC407 to IC501.  If no signal, check if the RF & servo signals from MD is entered to IC407.
Refer to the “No operation of MD” guide on Item 4.
2) Check the following I2S signal flow. < I2S audio signal Interface >
- DAC_BCK : IC501_Pin E1 --> IC601_Pin23
- DAC_LRCK : IC501_Pin D1 --> IC601_Pin22 (44.1 kHz)
- DAC_DATA : IC501_Pin E2 --> IC601_Pin24
- DAC_MCLK : IC501_Pin D2 --> IC401_Pin44
 If there is any trouble, check the power for each IC. The power is normal but, if the signal waveform to the IC is distorted or no signal, replace it with a new one.
3) check if “Digital audio AMP block” on Item 5-2 is normal.

NO SOUND
There is no sound output by DIGITAL AUDIO AMP DAMAGE, repair the set according to the following
BY DIGITAL AUDIO AMP DAMAGE (IN ALL FUNCTIONS)
check and replace IC701, IC702 on MAIN board.
How to troubleshoot (Countermeasure)
1) Check PWM_FL±, PWM_FR± & PWM_SW± signals from IC601 to IC701 & 702 each input function.  If no signal, check if I2S audio signals are entered to IC601.
Refer to “I2S audio signal interface” on Item 5-1.
2) Check PVDD. If PVDD is abnormal, check the SMPS.
3) Check +12 V for driving the gate of AMP IC.
a. All the powers are normal, but if +12 V is low, there is possible for AMP IC to be damaged.
b. Remove L701, L702, L703 and L704 one by one.
When removed a inductance, if +12 V is recovered, the IC connected to it was damaged.  c. Replace the IC with a new one.
4) Check the impedance between IC701/IC702_OUT_A/OUT_B & GND.
a. If the impedance is 0 Ω, the IC must be damaged.
b. After removing the heat sink, replace it with a new one.

NO SOUND
There is no sound output in the USB FUNCTION, repair the set according to the following
IN THE USB FUNCTION
Check and replace IC501 on MAIN board & IC302 on USB board.
How to troubleshoot (Countermeasure)
1) Check +5V_USB to USB board.  If the USB LED are turned on, the voltage is okay, if so not, check +5.6 V to pin6 of CN302.
2) Check USB D1± or USB D2± from MAIN board to USB board.
a. Check 2.0_D1±signals (pin U7, U8 ) or 1.1_D1± signals(pin A7, A8 ) to IC501.
b. Check USB± signals to CN302 (pin1, 2, 4, 5).  If there is any trouble, check the power for each IC. The power is normal but , if the signal waveform to
the IC is distorted or no signal, replace it with a new one.
3) check if “Digital audio AMP block” on item 5-2 is normal.

NO SOUND
There is no sound output in the AUX FUNCTION, repair the set according to the following

Check and replace IC201 on MAIN board.
How to troubleshoot (Countermeasure)
1) Check AUX_L/R signals to IC201 (Pin23, 24).
2) Check if MCS_BCK, MCS_LRCK & MCS_MCLK are entered from IC501 to IC201.
3) Check if ADC_DATA is entered from IC201 to IC501.  If no signal, check +5 V & +3.3 V(ADC) for IC201. If is NG, replace it a new one.
4) Check the following I2S signal flow from IC801 to IC602. If there is any trouble, check the power for each IC. The power is normal but, if the signal waveform to the IC is distorted or no signal, replace it with a new one.
5) Check if the digital audio AMP block is okay. If AMP is damaged, replace it with a new one.

There is no sound output in the TUNER FUNCTION, repair the set according to the following guide.
IN THE TUNER FUNCTION
check and replace IC201, TU500 on MAIN board.
How to troubleshoot (Countermeasure)
1) Check if TUNER_LR is entered from Pin1, 3 of TU500 to IC201(Pin26, 27).  If no signals, check +3.3 V for tuner power.
 Check if the tuner control signals (CLK, DAT, CE, RST, SLT) are entered from IC501 to TU500.
If it doesn’t work, replace TUNER with a new one.
2) Check if MCS_BCK, MCS_LRCK, & MCS_MCLK are entered from IC501 to IC201.
3) Check if ADC_DATA is entered from IC201 to IC501. If no signal, check +5 V & +3.3 V(ADC) for IC201. If is NG, replace it with a new one.
4) Check the following I2S audio signal flow from IC501 to IC601. If there is any trouble, check the power for each IC. The power is normal but, if the signal waveform to the IC is distorted or no signal, replace it with a new one.
5) Check if the digital audio AMP block is okay. If AMP is damaged, replace it with a new one.

NO SOUND
There is no sound output in the PORTABLE FUNCTION, repair the set according to the following guide.
IN THE PORTABLE FUNCTION
check and replace IC201 on MAIN board.
How to troubleshoot (Countermeasure)
1) Check PT_L/R signals to IC201 (Pin9, 10).
2) Check if MCS_BCK, MCS_LRCK, & MCS_MCLK are entered from IC501 to IC201.
3) Check if ADC_DATA is entered from IC201 to IC501. If no signal, check +5 V & +3.3 V(ADC) for IC201. If NG, replace it a new one.
4) Check the following I2S signal flow from IC501 to IC601. If there is any trouble, check the power for each IC. The power is normal but, if the signal waveform to the IC is distorted or no signal, replace it with a new one.
5) Check if the digital audio AMP block is okay. If AMP is damaged, replace it with a new one.

WAVEFORMS OF MAJOR CHECK POINTs

SMPS and Power amplifier schematic

Philips Home Theater System – HTS2500 –Power supply (SMPS) and Power Amplifier schematic, Disassembly, password setting, factory reset and more

Philips DVD-Video, DVD+R/+RW, DVD-R/-RW, CD-R/CD-RW, Audio CD, Video CD/SVCD, Picture CD, MP3-CD, WMA-CD, DivXCD, USB storage device

Amplifier
Total output power ......... 300 W RMS (30% THD) (for:/12/55/05)
Total output power ............................. 240 W RMS (10% THD),...... 300 W RMS (30% THD) (for:/94/98/78)

Power supply ................110-240V, ~50-60 Hz;
Power consumption .................... 55 W

Speakers

System .......................... full range satellite
Speaker impedance..................... 3 ohm
Speaker drivers ........................... 3” full range
Frequency response ................150 Hz-20 kHz

Subwoofer

Impedance ........................................... 12 ohm
Speaker drivers ................................... 133 mm (5.25”) woofer
Frequency response .................40 Hz-150 kHz

Laser specification

Type ..............Semiconductor laser GaAIAs (CD)
Wave length ............... 645 - 665 nm (DVD), 770 - 800 nm (CD)
Output power.........6 mW (DVD), 7 mW (VCD/CD)
Beam divergence .......................... 60 degrees.

Setting procedure & Repair instruction

Restore factory setting

a) Press <SETUP> button on R/C.
b) Select <preference setup> ,then press < OK >.
c) Select <default>,then press <OK> to conf rm.

Version control change

a) Open the Door,then,press “1” “5” “9” on RC.
b) Press <OK> button on RC.
c) TV will show message.

d) If current model doesnot match your set, use down arrow key on the remote to change.

Check on software version

a) Press <SETUP> button on R/C.
b) Select <preference setup> ,then press <OK>.
c) Select <version info>,then press <OK>.
d) TV will show message.

Password change

a) Press <SETUP> button on R/C.
b) Select <preference setup> ,then press <OK>.
c) Select <password> <change>,then press <OK> to confrm “0000” is default password supplied.

Trade mode

a) Press <Open/Close>button on R/C.
b) Press “2” “5” “9” on R/C,VFD will display “TRA ON “ or “TRA OFF

Upgrading new software
a) Check for the latest software version on www.philips.com/support.
Search for your model and click on ‘software&drivers’.
b) Copy the latest upgrading software onto a CD-R or USB storage device.
c) Insert the CD-R program disc or connect the USB storage device to the home theater.
d) Press <USB> button on R/C.
e) TV will show message

f) Press <PLAY> “>||” button on R/C.
g) TV will show message.

h) When the updated is complete ,the home theater automatically switch to standby.
Note: when upgrade in progress, please do not unplug or switch off the device.

How to replace the defective DVD Loader
a) Remove the defective DVD Loader..
b) Accordingly connect DVD Loader and “CN201”, “CN203” on the top of main board as shown here.:

c) Remove solder joint on the ESD protection point

Note: The ESD protection point on the Top side view of OPU must

be soldered if
- the DVD Loader is OK and needs to be disconnected from connector “CN201” and “CN203” of the main board.
- the defective DVD Loader is needed to be send back to supplier for failure analysis and to support back charging evidence.

Produce to change Tuner grid (only for /98 version)
In some countries, you can switch the FM tuning grid between 50 kHz and 100 kHz. Changing the tuning grid erases all preset radio stations.
a) Press<radio> button on R/C
b) Press <Stop> button on R/C.
c) Press and hold <Play> until (50 kHz) or (100 kHz) is displayed.
Note: repeating the same action will toggle back to it previous tuning grid setting.

Disassembly

Open the DVD Tray by using the Open/Close Button while the Set is ON and disconnect the mains supply after removing the Tray Cover.

Note: If this is not possible, the DVD Tray has to be open manually.
Take a mini screw driver about 2mm diameter and make a marking 24mm from the tip as shown in figure 2 . Place the set on its side, insert the mini screw driver till the marking and slide it towards the left as shown in figure 1 until the Tray moves out of the Front Panel.
2) Return the set to its upright position and remove the Tray Cover as shown in Figure 3 and close the tray manually by pushing it back in

3) Loosen 6 screws and remove the Top Cover by lifting the rear portion upwards before sliding it out towards the rear.
- 4 screws “A” at the back panel as shown in figure 4.
- 1 screw “B” each on the left & right side as shown in figure 5

Dismantling of the DVD Loader Module
1) Loosen 4 screws “ C “ at the DVD Loader Module as shown in figure 6.

Dismantling of the VFD+USB Board

Loosen 7 screws “D” on the top of VFD+USB Board as shown in figure 7.

Dismantling of the MAIN Board
1) Loosen 4 screws “ E ” on the top of MAIN Board as shown in figure 8.
2) Loosen 5 screws “ F ” at the back panel as shown in figure 9.

Dismantling of the POWER Board
1) Loosen 5 screws “G ” on the top of Power Board as shown in figure 10

Wiring diagram

SMPS PWB and schematic

Power Amplifier schematic

Pioneer CD RDS RECEIVER DEH-2350UB - Error codes, Service mode, service adjustments, disassembly and more

Pioneer car audio - DEH-2350UB/XNES, DEH-2350UBG/XNES, DEH-2350UBSW/XNES, DEH-2350UB/XSES, DEH-2350UB/XNES1

Rated power source...............14.4 V DC
(allowable voltage range: 12.0 V to 14.4 V DC)

Maximum power output .......50 W × 4

Continuous power output ...22 W × 4 (50 Hz to 15 000 Hz, 5 % THD, 4 load, both channels driven)
Load impedance ......................4 (4 to 8 allowable)

With a 2 speaker system, do not connect anything to the speaker leads that are not connected to speakers.

Power amp (sold separately)

Error codes

If a CD memory device is inoperable, or operation of such media is stopped by an error, the error mode is established and a cause of the error is displayed by an error code. Indication of error codes is intended to reduce the number of calls from customers and facilitate failure analysis and repair work in servicing.

Display method
If “0xFD” error mode is displayed in CD MODE (CD MODE area for display), an error code will be displayed in the MIN (minute display) and SEC (second display) areas,

The same code is displayed in the MIN and SEC areas.
The TNO area is blank (#0FFH), as it conventionally was.
• Display example of the main unit
Depending on the display capability of LCDs, the display format varies, as shown below. XX denotes an error number.
Note: In a case of an OEM product, the error display format is subject to the specifications used by the equipment manufacturer,

• Indications of error codes are available only during disc operations, because CD operations are unavailable if a mechanical error is generated.
• If the TOC cannot be read, this is not processed as an error, and operation continues accordingly.
• If you design a new head unit, be sure to use one of the display formats indicated in “Display example of the main unit.”

The 2 high-order digits of an error code denote the main
classification, shown below.
0x: Servo-related errors
1x: Servo-related errors
3x: Servo-related errors
5x: Mechanism-related errors

How to restore from each error is shown below.
0x, 1x and 3x: ACC-OFF then ON, CD-OFF then ON, Disc ejection
5X: ACC-OFF then ON, Disc ejection, Disc reloading.

Error codes and connector descriptions

Software update

The software of this product is stored in IC671.  Replace IC671 when making the version upgrade of software.

Service mode:  display test mode

The information such as the system microcomputer version is checked.

How to enter Test mode

Press “ 1 ” and “ 3 ” keys simultaneously to start resetting.

Operation key:  1 + 3

Processing:  Enter display test mode (2) Switch to next test mode.

Test items and CD Test mode details

After the [EJECT] key is pressed keys other than the [EJECT] key should not be pressed, until disc ejection is complete. When the key [2] or [3] is pressed during the Focus Search, the power supply should be immediately turned off (otherwise the lens sticks to Wall, causing the actuator to be damaged).
100TR Jump, the mechanism shall be set to the Tracking Close mode when the key is released.
When the power is turned on/off the gain of the RFAMP is reset to 0 dB. At the same time all the self-adjusting values shall return to the default setting.
Do not do Tracking Servo Close before doing Focus Servo Close. (Because the over current flows)

Disassembly

CD adjustment

Cautions on adjustments
In this product the single voltage (3.3 V) is used for the regulator. The reference voltage is the REFO1 (1.65 V) instead of the GND.
If you should mistakenly short the REFO1 with the GND during adjustment, accurate voltage will not be obtained, and the servo’s misoperation will apply excessive shock to the pickup. To avoid such problems:
a. Do not mix up the REFO1 with the GND when connecting the (-) probe of measuring instruments.  Especially on an oscilloscope, avoid connecting the (-) probe for CH1 to the GND.
b. In many cases, measuring instruments have the same potential as that for the (-) probe. Be sure to set the measuring instruments to the floating state.
c. If you have mistakenly connected the REFO1 to the GND, turn off the regulator or the power immediately.  Before mounting and removing filters or leads for adjustment, be sure to turn off the regulator.
For stable circuit operation, keep the mechanism operating for about one minute or more after the regulator is turned on.
In the test mode, any software protections will not work. Avoid applying any mechanical or electrical shock to the mechanism during adjustment.  The RFAGC and RFO signals with a wide frequency range are easy to oscillate. When observing the signals, insert a resistor of 1k ohms in series.
The load and eject operation is not guaranteed with the mechanism upside down. If the mechanism is blocked due to mistaken eject operation, reset the product or turn off and on the ACC to restore it.

Test mode
This mode is used to adjust the CD mechanism module.
To enter the test mode.
[4] + [6] -> BUP + ACC ON
To exit from the test mode.
Turn off the ACC and back up.
Notes:
a. During ejection, do not press any other keys than the EJECT key until the loaded disc is ejected.
b. If you have pressed the key during focus search, turn off the power immediately to protect the actuator from damage caused by the lens stuck.
c. For the TR jump modes except 100TR, the track jump operation will continue even if the key is released.
d. For the CRG move and 100TR jump modes, the tracking loop will be closed at the same time when the key is released.
e. When the power is turned off and on, the jump mode is reset to the single TR (91), the RF amp gain is set to 0 dB, and the auto-adjustment values are reset to the default settings.

Checking the grating after changing the pickup unit

The grating angle of the PU unit cannot be adjusted after the PU unit is changed. The PU unit in the CD mechanism module is adjusted on the production line to match the CD mechanism module and is thus the best adjusted PU unit for the CD mechanism module. Changing the PU unit is thus best considered as a last resort. However, if the PU unit must be changed, the grating should be checked using the procedure below.

Symptoms of Mal-adjustment:
If the grating is off by a large amount symptoms such as being unable to close tracking, being unable to perform track search operations, or taking a long time for track searching.

Checking Procedure
1. In test mode, load the disc and switch the 3 V regulator on.
2. Using the right and left buttons, move the PU unit to the innermost track.
3. Press key 3 to close focus, the display should read "91". 

Press key 2 to implement the tracking balance adjustment the display should now read "81". Press key 3. The display will change, returning to "81" on the fourth press.
4. As shown in the diagram  monitor the LPF outputs using the oscilloscope and check that the phase difference is within 75 .

5. If the phase difference is determined to be greater than 75 try changing the PU unit to see if there is any improvement. If, after trying this a number of times, the grating angle does not become less than 75 then the mechanism should be judged to be at fault.
Note:
Because of eccentricity in the disc and a slight misalignment of the clamping center the grating waveform may be seen to "wobble" ( the phase difference changes as the disc rotates). The angle specified above indicates the eaverage angle.
Hint
Reloading the disc changes the clamp position and may decrease the "wobble”