Welding in accordance with the small first, and the first light after the first years after, from low to high, after the first general special order of welding, first discrete components, integrated components, heat sensitive components. Finally, welding to external connections.
The welding sequence of the components is roughly as follows: resistance; ceramic capacitor; mid-cycle, input and output transformer; diode, transistor; point capacitor; double connection; potentiometer, antenna coil; battery clamp lead, horn lead.
For example, the printed circuit board diagram of radio is shown in Figure 1.
(1) install resistance. According to the mark on the printed circuit board, insert the component lead from the corresponding pad hole under the printed circuit board according to the resistance R1-R13. Do not insert the wrong position. When inserting, keep the resistance installation height consistent and the color ring direction consistent (the color ring direction should be convenient to check the reading). After inserting the resistance, the insulation panel is covered on the surface of the components with the help of the insulation panel, and then the insulation panel is turned over with the printed circuit board, so that the inserted components can be avoided dropping, and the bending process can be omitted, thus saving time and soldering the resistance lead firmly after flipping, and the soldering time is slightly longer than that of the printed circuit board. The welding time double-sided printed circuit board, avoid welding is not strong, after welding with diagonal pliers will cut the excess lead. The resistance welding procedure is shown in Figure 2.
(2) Install the ceramic capacitor in the same way as the installation resistance. Install, weld and cut the excess lead according to the printed circuit board diagram. The ceramic capacitor is welded as shown in Figure 3.
(3) installing diodes and transistors. According to the printed circuit board, diode and transistor lead location. When the diode is inserted, attention should be paid to polarity. The installation height should be consistent with the resistance. When installing the transistor, pay attention to the three polarities can not be mistaken, insertion can not force on the three leads, welding should be as short as possible, to avoid damage to the transistor. Diode and transistor welding is finished as shown in Figure 4.
(4) install mid cycle B3~B5 and input transformer B7. Installation of mid-cycle transformer according to the color of magnetic cap to distinguish the installation, yellow magnetic cap B3, white magnetic cap B4, black magnetic cap B5, in the printed circuit board diagram to find its symbol and determine the direction of installation. During installation, attention must be paid to the soldering of the middle lead wire and the copper foil.
(5) Installation of electrolytic capacitor, double capacitor C1A according to the printed circuit board icon will be electrolytic capacitor, double capacitor CBM-223P installed on the front of the printed circuit board, installation of electrolytic capacitor should pay attention to the polarity can not be wrong. The end of electrolytic capacitor and double capacitor welding is shown in Figure 5.
(6) install potentiometer and install antenna. Place the bracket on the antenna assembly on the reverse side of the printed circuit board, then fix it with screws, turn the circuit board over and firmly, and subtract the excess lead, potentiometer and antenna, as shown in Figure 6
(7) finally, the antenna will be welded to the twin midpoint.
After welding each type of components, check the welding quality to see if there is any wrong welding. Leakage welding and other problems, found problems to be corrected in time, this can ensure the success of the welding radio and enter the next process.
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