AIWA NSX-AJ50 (01) PDF Document

Main unit CX-NAJ50(U)/CX-NSZ50(LH)

FM tuner section

Tuning range: 87.5 MHz to 108 MHz

Usable sensitivity (IHF): 13.2 dBf

Antenna terminals: 75 ohms (unbalanced)

AM (MW) tuner section

Tuning range: 530 kHz to 1710 kHz (10 kHz step) / 531 kHz to 1602 kHz (9 kHz step)

Usable sensitivity: 350 µV/m

Antenna: Loop antenna

Amplifier section

Mid-high frequency amplifier Power output:

U: 20 W + 20 W (200 Hz to 20 kHz, T.H.D. less than 1%, 8 ohms)

LH: Rated: 20 W + 20 W (8 ohms, T.H.D. 1%, 1 kHz)

Reference: 25 W + 25 W (8 ohms, T.H.D. 10%, 1 kHz)

Total harmonic distortion: 0.1% (10W, 1 kHz, 8 ohms, DIN AUDIO)

Low frequency amplifier Power output:

U: 60 W + 60 W (50 Hz to 200Hz, T.H.D. less than 1%, 6 ohms)

LH: Rated: 60 W + 60 W (6 ohms, T.H.D. 1%, 130 Hz)

Reference: 75 W + 75 W (6 ohms, T.H.D. 10%, 130 Hz)

Total harmonic distortion: 0.1% (30W, 130 kHz, 6 ohms, DIN AUDIO)

Inputs: VIDEO / AUX: 500 mV; LH: MIC 1.0mV(10 K ohms)

Outputs:

SPEAKERS HIGH FREQ: accept speakers of 8 ohms or more

SPEAKERS LOW FREQ: accept speakers of 6 ohms or more

U: SURROUND SPEAKERS: accept speakers of 8 ohms to 16 ohms

PHONES (stereo jack): accepts headphones of 32 ohms or more

Cassette deck section

Track format: 4 tracks, 2 channels stereo

Frequency response: 50 Hz – 16000 Hz

Recording system: AC bias

Heads: Deck 1: Playback head x 1; Deck 2: Recording / Playback head x 1, erase head x 1

Compact disc player section

Laser: Semiconductor laser (λ = 780 nm)

D-A converter: 1 bit dual

Signal-to-noise ratio: 85 dB (1 kHz, 0 dB)

Harmonic distortion: 0.05% (1 kHz, 0 dB)

General

Power requirements:

U: 120 V AC, 60 Hz

LH: 120V/220-230V/240V AC switchable, 50/60 Hz

Power consumption: U: 110 W; LH: 130 W

Standby power consumption: 20 W (power-economizing mode set to OFF); 0.9 W (power-economizing mode set to ON)

Dimensions of main unit (W x H x D):

U: 240 x 324.6 x 271 mm (9 1/2 x 12 7/8 x 10 3/4 in.)

LH: 260 x 326 x 345 mm

Weight of main unit: U: 8.0 kg (17 lbs 10 oz.); LH: 9.0 kg

Speaker system SX-WNAJ50(U)/SX-WNSZ50(LH)

Speaker system: 3 way, bass reflex (magnetic shielded type)

Speaker units:

Subwoofer: 160 mm (6 3/8 in.) cone type

Full range: 100 mm (4 in.) cone type

Super tweeter: 20 mm (13/16 in.) ceramic type

Impedance: 6 ohms/8 ohms

Sensitivity: 86 dB/W/m

Dimensions (W x H x D): 240 x 324 x 271 mm (9 1/2 in. x 12 7/8 x 10 3/4 in.)

Weight: 4.8 kg (10 lbs 9 oz.)

The AIWA NSX-AJ50 employs a laser. When servicing, adhere to the following warning:

DO NOT APPROACH THE LASER EXIT WITH THE EYE TOO CLOSELY. IN CASE IT IS NECESSARY TO CONFIRM LASER BEAM EMISSION, BE SURE TO OBSERVE FROM A DISTANCE OF MORE THAN 30cm FROM THE SURFACE OF THE OBJECTIVE LENS ON THE OPTICAL PICK-UP BLOCK.

Caution: Invisible laser radiation when open and interlocks defeated avoid exposure to beam.

Body or clothes electrostatic potential could ruin the laser diode in the optical block. Be sure to ground your body and workbench, and use care that clothes do not touch the diode.

After making the connection, remove the solder from the designated point on the PICK-UP Assy P.C.B.

To prevent secondary defects when repairing the AIWA NSX-AJ50, you must perform a forced discharge of the electrolytic capacitors (C101, 102) in the power supply block. Follow these steps:

1. Remove the AC power cord.

2. Connect a discharging resistor to one end of a lead wire that has clips at both ends. Connect the other end of the lead wire to the metal chassis.

3. Contact the other end of the discharging resistor to the positive (+) side (+VH) of C101 for two seconds.

4. Contact the same end of the discharging resistor to the negative (-) side (-VH) of C102 for two seconds.

5. Check that the voltage across C101 and C102 has decreased to 1 V or less using a multimeter or an oscilloscope.

Select a discharging resistor from the following table:

Charging voltage (V) (C101, 102)	Discharging resistor (Ω)	Rated power (W)
25-48	100	3
49-140	220	5

Before exchanging the microcomputer on your AIWA NSX-AJ50, check the HOLD terminal to confirm if the microcomputer is defective.

When the HOLD terminal (INPUT) is “H”, the microcomputer is operating correctly. If it is “L”, the main power cannot be turned on. This could be due to a defective microcomputer or an abnormality in the POWER AMPLIFIER circuit triggering the detection circuit.

To judge if the microcomputer is good or not:

1. Turn on the AC main power.

2. Confirm that the main power is turned on and the HOLD terminal of the MICROCOMPUTER keeps the “H” level.

3. If the HOLD terminal is “L”, the abnormality detection circuit is working correctly, and the MICROCOMPUTER is judged to be good.

If the AIWA NSX-AJ50 does not work correctly because the microcomputer is not reset (even after re-inserting the AC power cord or performing a software reset), perform a forced reset using the following procedure:

1. Remove the AC power cord.

2. Short both ends of the electrolytic capacitor C113 (which is connected to VDD of the MICROCOMPUTER) with tweezers.

3. Connect the AC power cord again. If the MICROCOMPUTER returns to normal operation, it is good.

Also, check the soldering state of the microcomputer to ensure the trouble is not caused by poor soldering.

TUNER SECTION

1. Clock frequency Check

Settings: Test point: TP2.

Method: Set to AM 1710kHz and check that the test point is 2160kHz ± 45Hz.

2. AM VT Check

Settings: Test point: TP1 (VT).

Method: Set to AM 1710kHz, 530kHz and check that the test point is less than 8.5V (1710kHz) and more than 0.6V (530kHz).

3. FM VT Check

Settings: Test point: TP1 (VT).

Method: Set to FM 87.5MHz, 108.0MHz and check that the test point is more than 0.5V (87.5MHz) and less than 8.0V (108.0MHz).

4. AM Tracking Adjustment

Settings: Test point: TP8(Lch), TP9(Rch); Adjustment location: L951(1/3) at 1000kHz.

Method: Set to AM 1000kHz and adjust L951(1/3) so that the level at the test point becomes maximum.

5. FM Tracking Check

Settings: Test point: TP8(Lch), TP9(Rch).

Method: Set to FM 98.0MHz and check that the test point is less than 9dBμV.

6. AM(MW) IF Adjustment

Settings: Test point: TP5(Lch), TP6(Rch); Adjustment location: L802 at 1000 kHz.

7. DC Balance / Mono Distortion Adjustment

Settings: Test points: TP3, TP4 (DC Balance); TP8(Lch), TP9(Rch) (Distortion); Adjustment location: L801; Input level: 60dBμV.

Method: Set to FM 98.0MHz and adjust L801 so that the voltage between TP3 and TP4 becomes 0V ± 0.04V. Next, check that the distortion is less than 1.3%.

DECK SECTION

8. Tape Speed Adjustment (DECK 2)

Settings: Test tape: TTA-100; Test point: TP8(Lch), TP9(Rch); Adjustment location: SFR1.

Method: Play back the test tape and adjust SFR1 so that the frequency counter reads 3000Hz ± 5Hz and ±45Hz (REV) with respect to forward speed.

9. Head Azimuth Adjustment (DECK 1, DECK 2)

Settings: Test tape: TTA-330; Test point: TP8(Lch), TP9(Rch); Adjustment location: Head azimuth adjustment screw.

Method: Play back (FWD) the 8kHz signal of the test tape and adjust screw so that the output becomes maximum. Next, perform on REV PLAY mode.

10. PB Frequency Response Check (DECK 1, DECK 2)

Settings: Test tape: TTA-300; Test point: TP8(Lch), TP9(Rch).

Method: Play back the 315Hz and 8kHz signals of the test tape and check that the output ratio of the 8kHz signal with respect to that of the 315Hz signal is within 5dB.

11. PB Sensitivity Check (DECK 1, DECK 2)

Settings: Test tape: TTA-200; Test point: TP8(Lch), TP9(Rch).

Method: Play back the test tape and check that the output level of the test point is 140mV ± 3dB.

12. REC/PB Frequency Response Adjustment (DECK 2)

Settings: Test tape: TTA-602; Test point: TP8(Lch), TP9(Rch); Input signal: 1kHz / 8kHz (LINE IN); Adjustment location: SFR451 (Lch), SFR452 (Rch).

Method: Apply a 1kHz signal and REC mode. Then adjust OSC attenuator so that the output level at the TP8, TP9 becomes -20VU. Record and play back the 1kHz and 8kHz signals and adjust SFRs so that the output of the 8kHz signals becomes 0dB ± 0.5dB with respect to that of the 1kHz signal.

13. REC/PB Sensitivity Check (DECK 2)

Settings: Test tape: TTA-602; Test point: TP8(Lch), TP9(Rch); Input signal: 1kHz (LINE IN).

Method: Apply a 1kHz signal and REC mode. Then adjust OSC attenuator so that the output level at TP8, TP9 becomes 0VU. Record and play back the 1kHz signals and check that the output is -2dB ± 3.0dB.

FRONT SECTION

14. µ-CON OSC Adjustment

Settings: Test point: TP7 and GND; Adjustment location: L331.

Method: Insert AC plug while pressing POWER and TUNER function keys. Adjust L331 so that the frequency at the test point is 153.84Hz ± 0.15Hz.

There are different procedures based on the speaker type:

Type 1:

Insert a flat-bladed screwdriver into the position indicated by the arrows and remove the panel. Remove the screws of each speaker unit and then remove the speaker units.

Type 2:

Remove the grill frame and four pieces of rubber caps by pulling out with a flat-bladed screwdriver. Remove the screws from the holes where the rubber caps were installed. Insert a flat-bladed screwdriver into the position indicated by the arrows and remove the panel. Remove the screws of each speaker unit and then remove the speaker units.

Type 3:

Insert a flat-bladed screwdriver into the position indicated by the arrows and remove the panel. Turn the speaker unit counter-clockwise while inserting a flat-bladed screwdriver into one of the hollows around the speaker unit, and then remove the speaker unit. After replacing the speaker unit, install it by turning it clockwise until a “click” sound comes out.

How to Remove the PANEL, FR

1. Insert the tip of a flat head screwdriver into the gap between the PANEL, FR and the PANEL, SPKR. Tap the head of the screwdriver with a plastic hammer to create a clearance.

2. Insert a cut chisel into the clearance and tap the head of the chisel with a plastic hammer to remove the PANEL, FR.

3. Place the speaker horizontally. Tap the head of the cut chisel with a plastic hammer to remove the PANEL, FR completely.

How to Attach the PANEL, FR

Attach the PANEL, FR to the PANEL, SPKR. Tap the four corners of the PANEL, FR with the plastic hammer to fit the PANEL, FR into the PANEL, SPKR completely.