TYPICAL TROUBLESHOOTING OF MUSIC CENTERS "AIWA"

1). AIWA NSX-F9, F98, F99.

Manifestation of a defect: the unit turns off when the CD player plays at full power.

Elimination of the defect: short-circuit the emitter and collector Q117, increase the resistors R131, R132 to 1.5 kOhm, add capacitors of 0,027 uF capacitance parallel to the C145, C146 capacitors.

2). AIWA NSX-F9, F12, F15, S94, S95.

Defect occurrence: the machine does not turn on. The reason may be the failure of the power supply due to the breakdown of the output transistors in the ULF. Troubleshooting: replace faulty parts and, in order to avoid a future failure, perform the following changes in the diagram:

• Remove R237 (470 kΩ) and R239 (1 kΩ);
• Cut the diode cathode D227 from the circuit;
• Add a zener diode with a voltage of 10 V (for example, MTZJ10C) parallel to the capacitor C215. The zener diode should be connected to R290;
• Add a diode 1N4148N between the gate Q219 (the output of the transistor connected previously to the resistor R237) and the cathode D219. The anode of the added diode must be connected to the cathode of the diode D219.

3). AIWA NSX-S22, S50, S70.

Manifestation of a defect: Some CDs are not reproduced, as a rule - pirated ones.

Elimination of the defect: remove the capacitor C30 connected to the pins 41 and 42 of the IC11 IC (LA9241M). Change the capacitance of the C101 capacitor connected to pin 3 of IC101 (LC78622ED), with 0.1 μF at 0.033 μF.

4). AIWA NSX-AV65, 75, 85.

The appearance of a defect: with Dolby Prologic, at a low volume, there can be an arbitrary change in the balance of sound on the display.

Elimination of the defect: replace the microprocessor IC101. Perhaps, after replacing the processor, there will be a weak glow on the indicator outside the indication zone. In this case, add 25 resistors with a nominal value of 100 kΩ, a power of 0.25 W between the terminals 14 ... 36, 41, 42 and "ground".

5). AIWA NSX-S888, S999, S989, S898, A888, A999.

Customer complaints: there are too many basses in the sound, the speakers are "choked" with low frequencies. To eliminate this unpleasant phenomenon, the following improvement is proposed: Change the nominal value of the C614 capacitor from 0.1 μF to 0.33 μF; Connect the anodes of capacitors C451 and C452 resistors 1 kΩ with pin 16 of IC601; Change the value of resistors R635 and R636 from 180 kΩ to 100 kΩ. Change the capacitor rating C451 and C452 with 1.0 μF at 0.47 μF. Change the capacitor rating of C471 and C472 from 0.33 μF to 0.22 μF. This modification shifts the gain peak at low frequencies from 75 Hz to 100 Hz and changes the low-frequency gain peak by the T-Bass system from 60 Hz to 75 Hz.

6). AIWA NSX-AV65, AV66, AV75.

The appearance of a defect: a strong noise in the center channel when working with Dolby Pro-Logic. When the volume is adjusted, the noise level changes. Troubleshooting: Short circuit terminals 24 and 25 of the IC501; Cut the path between pin 24 IC501 and the anode terminal of capacitor C702; Remove the capacitor C701; Remove the jumper between pin 27 of IC501 and resistor R551; Connect terminal 27 IC501 and the anode of capacitor C702 with a wire. Connect the lead of the resistor R551, which was previously connected to pin 27 of IC501, to the track on which the cathode of capacitor C701 was soldered.

7). Fault.

In many CD players there is a disease - after a year of intensive work the discs on the first songs are not read properly or service information is not read. The thing is that the carriage of the laser with one edge moves along the plastic guide on which the lubricant dries. Remove all remnants of the old grease and put a new one (silicone, graphite). All this - provided a clean laser lens.

8). AIWA.

Models: everything where the CD-engine uses the CXD2540Q signal processor. Manifestation of a defect: sometimes when playing discs, clicks are heard in both channels.

Elimination of the defect: change the value of the resistor R155 (20 pin CXD2540Q) from 3.3 kΩ to 1.5 kΩ.

9). AIWA.

Models: all systems with built-in decoder Dolby Pro-Logic.

Manifestation of a defect: no sound in the Surround channel.

Elimination of the defect: it is necessary to connect both speakers correctly. The fact is that the Surround channel is monaural, and the speakers are connected in series.

10). The AIWA Music Center (different models).

Jamming the cassette in deck "A". The problem is that in the deck "A" the passive coming from the motor only touches the right-hand tone of the shaft to a third of the circumference and starts to slip at this point. You can find a tighter pasik, or you can just take a weak solution of rosin with alcohol and napanifolit passik. Coupling of the passive with the tone shaft after this procedure is greatly improved, and everything is working fine.

eleven). Problems with the CD player.

The AIWA music center , with 3 disc laz. Player, when you try to turn on the CD, the carousel spins without stopping for a while, then it is blocked. Under the carousel there is an optocoupler, curtains of different lengths during rotation cross the optical axis, thus determining the number of the disc. I see the signal at the output, up to the control processor, the impulses reach (14 feet LC .........) It would seem that percent. They do not perceive .... The constant component at the output of the phototransistor has confused the light flux does not fully open it. Increased the emission of the LED by placing in parallel a quenching resistor the same and the device earned.

12). Problems with the tape drive mechanism.

Do not work decks - spontaneously clap mechanisms of drive heads. The signal level indicators in CD, FM modes are constantly at the maximum.
Cause: ripple in the "-50V" circuit on the main board. False triggering of position sensors due to ripple.

13). Models: all mini and midi systems.

Display of a defect: incorrect reproduction of the programmed sequence of playing tracks. To clarify the diagnosis, program the playback of 10 and 12 tracks. If after 10 tracks the unit starts playing 11 tracks instead of 12, then it is necessary to replace the system microprocessor (the chip is located on the front of the device, the number is m / s, usually IC101, sometimes IC201).

14). Problems with the CD player.

A frequent malfunction is a failure when playing a CD. The reason lies in the contamination of the optical system. The simplest case is the dusting of the upper lens. It is enough to wipe the surface of the lens with a cotton wool gum. Do not use solvents and do not press strongly on the optics. The company Aiwa itself supplies a special compound for lens cleaning, but you can do without it.

15). Problems with controlling the AIWA audio center.

The mini-and midi control microprocessor normally works if the HOLD signal is in the log state. 1. If the HOLD signal is logged. 0, the internal circuit prohibits the operation of the microprocessor. Therefore, before deciding to replace the microprocessor, check the status of the HOLD signal on it. Typically, if the HOLD signal is in the log state. 0, then this indicates a malfunction or power supply, or VLF. Most Aiwa audio equipment uses Sanyo's LC **** microprocessors. These chips have a HOLD signal at pin 19. There are cases when there is no "reset" of the microprocessor. Externally, it looks like this: no symbols glow on the display, or all symbols are lit, the device does not respond to the control buttons. The complete de-energizing of the device does not help either. Before deciding to replace the microprocessor, try the forced reset operation by pressing Stop and Power. If this does not help, completely disconnect the device and discharge the capacitor C113. Turn on the machine. If it has started to function properly, then the microprocessor is working. Check the circuitry for generating a RESET signal and powering the processor.

16). Problems with the tuner.

Models: all audio centers, where the tuner is tuned using the PLL synthesizer on the LC72131 chip. The appearance of a defect: there is no reception in the FM band, the clock does not work (the time is "standing"). There are three possible reasons for this behavior of the audio complex: The IC720 chip (LC72131) is defective; Faulty quartz X721 (7.2 MHz), stabilizing the oscillator frequency in the LC72131 chip; No power (5.6 volts) on the vyv. 17 chips LC72131.

This defect also occurs in other models of Aiwa audio equipment, where a similar PLL synthesizer chip is used. Therefore, with similar symptoms, the defect itself can be looked for in a similar way. When installing quartz with a certain deviation from the set frequency, the clock can hurry or lag. Probably, quartz will have to be selected, as there are no tuning containers.

17). Safety during repair.

Recently, I encountered a rather unpleasant situation during the repair of the AIWA CX-NS50EZ music center . During the disassembly and dismantling of the boards, I forgot to discharge the capacitors of the power supply. I accidentally touched the metal case with the mounting side of the board (on it there is a scheme of the power supply unit, ULF, receiver, etc.). Having collected the center, I plug it into the socket, the protection relay periodically starts to click. Schemes were not at hand. After spending a decent time, I found a broken resistance R238 (50 Ohm) in the amplifier.

So, during the repair, be careful, discharge the capacitors of the power supply.