Improved circuit of Sanyo DC-SL mini-combination speaker
A Sanyo DC-Sl mini stereo is placed in my bedroom. It has been used for years since it was used. Although it does not have the fashionable VCD / DVD playback and HP3 decoding functions, I am still quite satisfied with it. The appearance of this stereo is more avant-garde, with a large multifunctional LCD screen of 10cm × 6cm, a sliding CD tray panel, etc. It still looks generous and chic in the eyes of today. Its function and detail design are very convenient and considerate, teaching code Kara 0K reverb and song "remove vocal" function meter users can sing the song without special accompaniment band, "WAKE UP" wake-up function can make the boot volume from zero Start to turn up slowly, will not produce the uncomfortable feeling of waking up suddenly in sleep. In addition, the products produced in previous years pay more attention to quality and materials. The volume is small and the output power is large (the thick film power amplifier with dual 24V power supply). Its bass effect is significantly better than some similar small audio products currently on the market.
In my spare time, I like to disassemble the electrical appliances and make some small and noisy transformations. This audio naturally cannot be "survived". After several times of disassembly, the sound quality and performance of the machine have been improved to a certain extent. Now the motoring process is introduced as follows, for your reference when you are playing the small combination audio.
1. Motorcycle speaker: The original SX-MS1 speaker is a small two-unit plastic box structure with cross wooden bar reinforcement. The speaker is 6Ω25W 1 inch treble and 6Ω25W 5 inch bass each, using a common electrodeless capacitor for simple frequency division. Due to the limited volume of the cabinet, it is inconvenient to make major changes to the crossover structure. Only the crossover capacitor is replaced with a 3.3μF RIFA capacitor, and then the cabinet is filled with an appropriate amount of sound-absorbing cotton. After the change, the high frequency of the speaker can be heard more delicate, The low frequency is more stable and powerful.
Second, replace the capacitance of the audio circuit: The method of replacing the capacitance is simple and easy, suitable for playing mini stereos and walkmans. The main method is to increase the capacity of filter capacitors and coupling capacitors at all levels to make the low-frequency response more solid, while adjusting the capacity of individual high-frequency bypass capacitors to reduce the loss of high-frequency details. The filter capacitors C4902 and C4903 of the power amplifier power supply were increased from 2200μF / 35V to 6800μF / 35V. Because the larger capacitor cannot be placed at the printed board, the thicker wire should be used to extend the wiring of the capacitor pin and fix it at a nearby location. Filter capacitors C4918, C4919, C1502 increased from 47μF to 220μF, coupling capacitors C2705, C2805, C4701, C4801, C4517, C4617 increased from 1μF to 3.3μF. As far as possible, select electrolytic electrolytic capacitors from famous manufacturers such as ELNA. Reduce the high-frequency bypass capacitors C4700 and C4800 of the input end of the power amplifier IC STK4132MK2 from 820pF to 100pF, and the stereo decoding de-emphasis capacitors C2319 and C2320 of the radio IC LA1830, 14 and 15 pins are reduced from 0.015μF to 8200pF. If conditions permit, you can also replace several SMD op amps 4558 with better performance ones.
Third, hit the radio circuit: In order to improve the reception effect of the FH band, a high-level amplifier can be added. The circuit is shown in Figure 1. Coil L is made of 5mm turn enameled wire wound around 5 turns on ballpoint pen core. Transistor 2SC3355 can be replaced by common 9018, but the latter performance index is slightly worse. C1 ~ C3 use high frequency ceramic capacitors, other components are selected small The specification is directly lap welded on the copper foil surface of the printed board next to IC211 (TA8176SN). Note that the speed must be fast when welding high frequency transistors. After adding high-fidelity, listening to FM stereo broadcasts no longer has annoying noises, and the music sound is more pure. The second is to increase the capacity of the backup memory capacitor of the audio microprocessor. Replace the C4309 (1000μF) with a NEC5.5V 1.0F capacitor in series with a 51Ωn resistor, so you do n’t have to worry about the loss of the frequency of the storage station caused by the occasional power failure. Due to the relatively large volume of the newly-replaced memory capacitor, hot melt adhesive can be used to paste it in the vicinity of the printed board, and then the circuit connection is made with thin wires.
4. Add standby auxiliary power supply. The speaker uses a larger power transformer. As long as the power plug is plugged in, the transformer is always energized regardless of whether the machine is turned on or not. The temperature rise inside the machine for a long time is obvious, and the standby power consumption is also large. Although the machine can be unplugged when not in use, it will lose the functions of regular wake-up and remote start-up, and frequent plugging and unplugging is also troublesome. After studying the original circuit, I added a low-power standby power supply (see Figure 2). The circuit is composed of a transformer T2 and peripheral rectification and control circuits. On the one hand, it supplies power to IC491 (AN7809F) to supply infrared receiving circuits and microprocessor circuits, and is also responsible for automatic control of the main power transformer T1. T1 is no longer connected to the mains supply during standby. Only when the microprocessor issues the "PO RY" start command and the relay J1 is closed, T1 will be energized. Since "PO RY" is low-level enabled, Q1 is added as an inverter. D2 acts as an isolation to prevent standby power from sending power to unrelated circuits. In the picture, Q4902, C4909, IC491, R4957 are the component numbers of the original audio circuit, and the rest are new circuit components. T2 selects a small high-quality transformer below 10W, and fixes it with a screw outside the cover of the rear of the audio host (does not affect the appearance of the front). Relay J1 uses a model with a coil voltage of 12V and a contact current of 5A or more. Do it on a small circuit board and put it inside the speaker.
V. Modify the LCD backlight circuit. The original host display uses 6 mini incandescent light bulbs plus a filter cover to produce a green backlight. The circuit has high heat generation and high power consumption. It is now replaced by the same number of super bright white LEDs. The backlight power consumption is reduced, and the effect of the black body with the white display is even more "cool". Due to the serial-parallel combination of the LF port, the wiring of the printed board needs to be slightly modified. For the specific circuit, please refer to the relevant part in the upper part of Figure 2. Compared with incandescent light bulbs, LEDs can emit light as long as there is a slight current, so I use standby auxiliary power to provide them with a continuous current of a few milliamperes, so that even after turning off the lights at night and turning off the lights, you can view them with a faint backlight The clock display on the LCD screen has the effect of "luminous clock", beautiful and practical, but the additional power consumption is very small. Here, the LED needs to use a Φ5mm scattered light type, not a condensing type, otherwise the brightness of the LCD screen will be uneven, and unsightly light spots will appear. If you can't find this kind of "scattered light" LED, you can replace it with the SMD LED of the mobile phone (first add pins to the SMD LED with a fine enameled wire, and then solder it to the printed board), the effect is also good.
Wonderful audio circuit atlas please check: http: //
2Pans Buffet Server,Buffet Server Warming Plate,Buffet Server Warmer,2Pans Buffet Server Warmer
Shaoxing Haoda Electrical Appliance Co.,Ltd , https://www.hotplates.nl