(1) No crossover circuit is allowed in the printed circuit on PCB board. For wires that may be crossed, two methods of "drilling" and "winding" can be used. That is to say, let a lead wire "drill" through the gap at the foot of other resistors, capacitors and triodes on the PCB board, or "wind" through one end of a lead wire that may cross over. In special cases, if the circuit is very complex, in order to simplify the design, wire bridging is also allowed to solve the problem of cross circuit.
(2) There are "vertical" and "horizontal" installation methods for the resistor, diode, tubular capacitor and other components. Vertical method means that the component is installed and welded perpendicular to the PCB board, which has the advantages of saving space. Horizontal method means that the component is installed parallel and close to the PCB board, and welded, which has the advantages of good mechanical strength for the installed component. For the two different installing components, the hole spacing of the components on the PCB board is different.
(3) The ground point of the same stage circuit shall be as close as possible, and the filter capacitor of the same stage circuit shall also be connected to the ground point of this stage. In particular, the ground points of the base and emitter of the transistor at the same stage should not be too far away from each other, otherwise the copper foil between the two ground points will be so long that it will cause interference and self excitation. The circuit with such "one point grounding method" works stably and not easy to self excitation.
(4) The general earth wire must be arranged in strict accordance with the principle of high-frequency, medium frequency and low-frequency from weak current to strong current. It is not allowed to randomly connect them over and over again. It is preferred to connect long wires between stages, but also to abide by this regulation. In particular, the earth wire arrangement for frequency inversion head, regeneration head and frequency modulation head is more strict. If not, it will generate self excitation and fail to work.
Large amount of surrounding earth wire is often used in high frequency circuits such as FM head to ensure good shielding effect.
(5) The strong current lead wires (common earth wire, power supply lead wires, etc.) should be as wide as possible to reduce the wiring resistance and voltage drop, and to reduce the self excitation caused by parasitic coupling.
(6) The routing with high impedance should be as short as possible, and the one with low impedance can be longer, because the wire with high impedance may absorb signals, causing circuit instability. The power wire, earth wire, base wire without feedback component and emitter lead wire are all low impedance wires. The base wire of emitter follower and the earth wire of two channels of recorder must be separated and formed into one circuit respectively until the end of the effect in which they connect with each other again. If the two routes of earth wires are connected randomly, it’s easy to generate crosstalk and reduce the separation degree.