JPH0311666B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for discovering the short status of a particular circuit portion or circuit element in an electronic circuit. Conventionally, continuity measuring means such as so-called testers have been used for this purpose, but in a particular circuit, it is difficult to determine the shot location using such means. This is often impossible with components still mounted.

For example, as shown in FIG. 1, capacitors C ₁ , C ₂ ,
If C ₃ , diode D ₁ , coil L ₁ , or even socket or connector P ₁ are connected, for example, if any of the circuit elements is faulty and exhibits a short condition, continuity measurement as described above can be carried out. It is completely impossible to discover the situation unless you remove each part one by one and shot-check each part individually. Furthermore, the printed patterns on the mounting parts of _P1 such as sockets and connectors are not visible, making it extremely difficult to detect pattern shorts. These short situations cannot be determined even if an ohmmeter with a resolution of 1/1000 ohm is used.

The present invention utilizes a phenomenon in electronic circuits in which the oscillation frequency of a UHF band oscillation circuit fluctuates greatly in response to subtle changes in the oscillation constant. Therefore, it is incorporated into the oscillation circuit as an inductor in the short path. Two contact leads are provided in connection with this oscillator circuit, and when these leads are brought into contact with both ends of the part on the shot line, the oscillator circuit will display a certain natural frequency during shooting, and the value of this frequency Determine the short part by knowing this in advance.

FIG. 2 illustrates the principle of the invention, in which , indicates a printed circuit conductive pattern similar to that described in connection with FIG. 1, in parallel with which, for example, three capacitors
Assume that C ₁ , C ₂ and C ₃ are connected. 10
is a 400MHz band oscillation circuit, 11 and 12 are contact leads extending from the circuit, and 13 is a frequency counter that reads the oscillation frequency. Frequency counter 13
may be well known. In Figure 2,
Assume now that capacitor _C2 is in the shorted state. Assume that the lead rods 11 and 12 are brought into contact just below the capacitor _C1 . In this case, an inductor (coil) corresponding to the route indicated by 14 is inserted into the oscillation circuit. Of course, in this case, actually the capacitors C ₁ and C ₃
and the equivalent circuit of the printed pattern also have an influence. In this figure, the display on the frequency counter 13 is highest (high frequency value) when the lead rod is placed just below the shorted capacitor C ₂ because the inductance, that is, the short circuit route is at its minimum.
indicate. Since the oscillation frequency is set to the UHF band, the distance (a-b) between capacitors _C1 and _C2 is 1
It is possible to make a sufficient distinction even at a distance of about cm. In actual use of the present invention, the tips of the two lead rods are shot in advance, the frequency display at that time is known, and the difference between the frequency at that time and the frequency of the above-mentioned measured value is a predetermined value determined by experiment. For example, I learned that when a part approaches 1MHz or less, it can be determined that that part is shooting.

FIG. 3 shows an embodiment of the oscillation circuit 10 shown in FIG. 11 and 12 are copper lead rods of 1 mmφ and 25 mm, and 15 is an impedance forming the route 14 in FIG. It is connected to a frequency counter 13 via a coaxial cable 16, and the oscillation frequency is read. This oscillator has impedance 15 of Z=
It is adjusted to oscillate at 405.0MHz when O+jO [Ω].

[Brief explanation of the drawing]

1 and 2 are schematic diagrams used to use the principles of the present invention, and FIG. 3 is a detailed circuit diagram of some of the elements in FIG. 2, where 10 is an oscillation circuit;
1 and 12 are contact lead rods, and 13 is a frequency counter.

Claims (1)

[Claims] 1. In a method for determining the shot status of any of a plurality of parallel-connected circuit elements or components, two terminals from an oscillation frequency determining portion of a high-frequency oscillation circuit are brought into contact with the circuit element or component,
The above system is characterized in that the circuit element or component is determined to be shooting when the difference between the frequency of the high frequency oscillation circuit at that time and the frequency when the terminals are shot is less than or equal to a predetermined value.