Keywords: Fu-50, ambiguous circuit, power amplifying circuit
Author: Yu Lian Friendship
The circuit principle of the machine is shown above, and the FU 50 is connected to a triode operating state.
To achieve good stability, reduce the fracture of the whole machine. The signal is not pursued as high sensitivity. Do not use high amplification factor, such as 6J5, 6J8, etc. 6N8P belongs to low μ tubes, which is very good, very suitable for CD large dynamic signal sources.
Based on the principle of "simple supreme", a crystal high back pressure recovery diode is rectified.
The cab case is made as a piece of art. This machine uses a 3mm thick copper plate (more brass plate more than the brass plate), using a combination assembly method, cut the copper plate in the cutting machine.
The φ16mm brass rod is selected 45mm long copper columns in the machine tool, and the center of the two ends attack φ6mm threads, deep 2mm, side shaking 3 × 3mm slots to 90 °. Then process 8 bolts are used to fasten the support housing, and the dimensions are shown in the figure.
The vertical and horizontally across the upper and lower panels The cross-point drill φ6mm circular hole is rotated on the panel with the copper column with the copper column, and the front and back and right panels are inserted into the copper column slot. The lower panel is tightened with the other end of the copper pillar and drills the ventilation of the air. The composite rear housing is polished with the grinding machine, and it is necessary to face and clean, and the angular angular is obvious. Four feet are stable. The following board bolts are the whole machine support feet, and the length of the panel can be obtained to obtain different specifications, adapt to a variety of bile duct upgrades.
The production output transformer of the output transformer is the key to determining the quality of the whole machine. The coil structure arrangement is directly related to frequency characteristics. The primary inductance is large enough. The coil distribution capacitor is minimal. Meet the equilibrium needs of high bass bands.
The film has a thickness of 0.35 mmEi core, a tongue width of 32 mm, a stack of 58 mm, and the power is 15-30VA.
The frame is used with a thick glass wire plate, and the tongue is width, the tongue is long, and the stack is stacked. Use the layered interval of the secondary 4 seconds. That is, the primary coil is divided into 4 equip clauses between the secondary coil.
The coil winding is shown in the figure. The layers of the interlayer lead cannot be received, and the welding taps are on the outer side of the wire, and the wire pack is prevented from being protected. The interlayer insulation is 0.0mm thick cable paper, the first stage is used with a two-layer kraft paper or blue shell paper, the outer layer is covered with kraft paper, and the wire is allowed to have the remaining space, if there is a recess with insulated paper Start up, print the word. The iron core is going to insert. The pad is 0.12 mm thick paper to prevent the ferroelectric saturation. The output transformer core wire frame is made as shown below.
Under amateur conditions, the use of multimeter is detected, and the first-level and iron core have no short circuit. The primary DC resistance is about 214 Ω. Access 220V50Hz electricity, measure the secondary 4Ω end of 8V, 8Ω terminal is around 12V. Normally, put the drying box of about 100 ° C to the tide. Put it in high quality insulation paint by heat, remove it when you do not bubble bubbles. After drying, the iron core angle hanger patent leather was polished with a grinder. Take it from the black paint sprayed the core. The bolt is tightened with a 3mm thick brass plate.
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Printed circuit board makes this machine with a printed circuit process. The connecting lines between each stage are reduced. It is very advantageous to eliminate inter-line interference.
The printed plate is selected from 1.2-1.5mm thick glass fiber single-sided copper plate.
Carefully use the knife cut. The line width is 3-4mm. The spacing is 2mm.
The power supply, the opening of the output transformer, the fixed hole position of the biliary component is very accurate, and all the hole positions on the upper panel of the casing are consistent, and the back edges of the two sides should be left with signal input terminals, audio output terminals, potentiometers, switch plugins. Space occupied. The power supply, the output transformer winding leads are introduced into the printing line corresponding to the printing line, and the copper rivet is welded to the printed plate with φ2mm empty core copper rivets. Standard bridge, fine-tuning resistance tape soldering copper foil surface. Electrical resistance, diode horizontal, lead bend 90 °. The printed plate is designed to take into account the application of bile duct EL34, KT88, 6550A, 6P3P, as long as the tube is replaced, and the correlation line can be changed.
The selection of the components is quite demanding for power supply, and there is a large power reserve. If the power transformer is self-contained, the shield is made with 0.25 mm thick purple copper skin.
The core is selected from the EI type high-quality high silicon tablets, and the cross section is sufficient. Power is preferably 250-300VA. The power supply circuit and the power supply transformer are winded with the data below.
High-pressure filtration can adopt an oil immersion capacitor with excellent performance. But the volume is large. Secondly, Philips Blue Hexagon, Sustic, Germany Roe, Japanese Elna, Ruby, Black Widow, and Domestic Need Color TV Special Electrolytic Capacitor. The withstand voltage is 450V or more.
The bile duct FU50 is selected to use the "Beijing" brand Early J-class products, and the protective cover is not suitable for the installation, and the novel protective cover can be made.
Switching model is the first Soviet Union TY50.6N8P selection "Dawning" J-grade product.
Level coupling capacitors are key components that affect sound quality, try to use tops. For example, French 0.22-0.47μF / 600VSolen big s capacitors, German old WiMA (Wema) is mild, red Wema and ERO capacitors are supple. Sibbi, Western Electric is extraordinary.
Incentive grade cathode bypass capacitor selects Nissan ELNA audio special high-speed electrolysis, resistance is selected with low noise five-ring series metal film resistance or domestic red robe, and power should meet the requirements. The volume potentiometer selects the Nissan ALPS.
A special type of gallbladder selection plate, and a brass rod processing is used. Audio output terminal block selects advanced pure copper or gold-plated finished product.
The signal input line selects Osel, and the monster RCA is selected from the 8-port 24K gold plug.
Debug confirmation No misoperation, test machine is inserted normally into the electronic pipe adjustment work point. The anode, the cathode, and the gate voltage error should be less than 5%. 6N8P anode voltage 90-100V. The cathode electrical resistance is reduced to 2V, and the excitation stage anode voltage is 250-260V.
The cathode resistance dropped 100-108V. Carefully adjust the fine-tuning SW23 to make two Fu50 gate bias at -55V.
The anode voltage is around 380V. The tube needs to be biased, and the self-contained depletion is less profitable. It uses a fixed bias to reduce the power supply power of the cathode resistance, save the high power resistance bypass capacitance. 65V windings and rectification, filter adjustable circuitry must be reliable. Also pay attention to the filament voltage does not exceed 50% of the rated voltage, more than 10% will cause the tube screen to be extremely red, premature aging damage.
The amplifier voltage is high, and the "spark method" is not available in debugging. Prevent instantaneous overcurrent damage to tubes. Output transformer secondary is not allowed to open. Self-excited, whistling can call the primary leads of the output transformer. The delay time is determined by the RC product, and this machine is selected for about 40 seconds. When the bile duct cathode is hot and higher than the high pressure, the tubes can be extended, and the latency shows the blue-ray diode is eye-catching.
Naked bile duct 6N8P, filter capacitor should be shielded, with different sizes of copper rods, copper-proof, threaded ventilated-circular copper hoods, and bronze natural red.
Listening to the whole machine, the work point of all levels should meet the requirements.
If there is an abnormality to replace the relevant components, the standby enters the best stable state to listen.
Source: Domestic top DVD, domestic FJDA-60 type speaker, divided point 2800Hz. Classic CD audio disc, piano concerto "Yellow River", violin concerto "", the whole machine sound is warm and sweet, the bass is thick and powerful. People are full, unique, very charming.
The FU50 can be considered as "" bile duct in the audio. Good quality and low price, the salary layer is fever, you may wish to try it.
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