As a PCB Company, share with you how to use the circuit online repair tester to repair the circuit board. First look and then use the tools: digital multimeter, magnifying glass. When you get a PCB circuit board to be repaired, you should first see how. Use the circuit online maintenance tester to repair the circuit board.

1. Principle 1 Look first and measure later

Use tools: digital multimeter, magnifying glass

When you get a PCB to be repaired, you should first look at it and make a visual inspection:

⒈Whether there is a broken wire, whether there are burn marks

⒉Whether the discrete components are disconnected

⒊Whether there are broken wires or sticky wires on the PCB

⒋Whether anyone has repaired, moved, whether it is virtual welding, missing welding, reverse insertion, etc.

After confirming that there is no above, use a multimeter to measure the resistance between the power and ground of the circuit board. Generally, the resistance of the circuit board is above 70 ~ 80Ω. If it is broken or partially broken, you can power on the PCB and touch the temperature of each component with your hand. The hottest object will be the key suspect. If the resistance is normal, you can use a multimeter to detect it.

2. Principle 2 First-out, then-in, enumeration test:

Use tools: online maintenance instrument, marker pen,

Because the online maintenance instrument integrates two kinds of fault diagnosis technologies, one is the standard comparative test method (ICFT) based on the device test program library; the other is the real-time comparative scanning test method based on the VI curve.

When using ICFT for chip testing, the following two test blind spots may appear:

The test program library has not yet established a test program for a chip, that is, there is no such chip in the library.

Even though the library has been built, the "online test" fails.

For the test blind zone without this chip in the library, only the symmetry of the board or the comparison with the good board can be measured by VI curve. For the blind zone that is "online test", there are two possibilities ① The logic function of the device NG ② Test misjudgment . For the latter, do not rush to weld, you can make marks first.

When using the ASA-VI curve scan, the following test blind spots may also appear:

The fit of the curve comparison results is not very tight, but within the allowable error.

There is no comparable object, that is, the same good board cannot be found.

For blind areas where the fit is not very tight, the load on the two circuit boards must be the same, and they cannot be compared in the absence of a few chips. In addition, due to the different service life of the two circuit boards, including the resistance of the components Different performance degradation of components will cause the difference of VI curve. Experience has shown that the fit of the comparison results of the VI curves is not very tight, and the probability of failure is not obvious.

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