SMT component failure
Some SMD components are very small, with an ordinary multimeter pen test maintenance is very inconvenient, one is easy to cause a short circuit, the second is coated with an insulating coating of the circuit board is inconvenient to contact the metal part of the component pins. Here to tell you a simple method, will bring a lot of convenience to the test.
Take two of the smallest number of sewing needles, will be close to the pen with a multimeter, and then take a multi-stranded cable in the thin copper wire, with a thin copper wire will be tied to the pen and sewing needles, and then welded firmly with solder. So that with a fine tip of the pen to measure those SMT components when there is no longer a short-circuit risk, and the tip of the needle can pierce the insulating coating, hit the key parts, no longer have to bother to scrape the film film.
Public power short-circuit fault
Circuit board maintenance, if you encounter a public power supply short-circuit failure is often a big head, because many devices share the same power supply, every device with this power supply is suspected of short-circuit.
If not many components on the board, the use of "hoeing" approach can eventually find a short-circuit point; if too many components, "hoeing" can not hoe to the situation depends on luck. Recommended here a more useful method, using this method, twice the effort, often quickly find the fault point.
To have a voltage and current are adjustable power supply, voltage 0-30V, current 0-3A, this power supply is not expensive, about 300 yuan. Open circuit voltage to the device supply voltage level, the first current to the minimum, the voltage will be added to the circuit of the power supply voltage points such as 74 series chip 5V and 0V terminal, depending on the degree of short-circuit, slowly increase the current.
Touch the device by hand, when a device touched the heat is obvious, this is often damaged components, can be removed for further measurements to confirm. Of course, the operation of the voltage must not exceed the device's operating voltage, and can not be reversed, otherwise it will burn other good devices.
Board failure
More and more boards used in industrial control, many boards using the gold finger inserted into the slot. Due to the harsh environment of the industrial site, dusty, humid, corrosive gas environment prone to poor contact failure of the board, many friends may be through the replacement of the board to solve the problem, but the cost of purchasing the board is very considerable, especially some of the imported equipment board.
In fact, you may wish to use an eraser on the gold finger repeatedly rubbed a few times, the gold finger on the dirt cleaned up, and then try the machine, may solve the problem, the method is simple and practical.
Electrical faults
A variety of good and bad electrical failure from the probability of the size of the following cases:
Poor contact: poor contact between the board and the slot, cable internal fracture when through when not pass, wire plug and terminal contact is not good, component soldering, etc. are such;
Signal interference: for digital circuits, in a particular situation under the conditions of the failure will be presented, it may indeed be too much interference affects the control system to make it wrong, there are circuit board individual component parameters or the overall performance of the parameters appeared to change, so that the ability to anti-jamming tends to the critical point and thus failures;
Component thermal stability is not good: from a large number of maintenance practices, which is the first electrolytic capacitor thermal stability is not good, followed by other capacitors, transistors, diodes, ICs, resistors and so on;
Circuit board with moisture, dust, etc.: moisture and dust will be conductive with the resistance effect, and in the process of thermal expansion and contraction of the resistance value will change, the resistance value of other components will have a parallel effect, the effect is stronger when the circuit parameters will be changed to make the fault occur;
Software is also one of the factors to consider: many parameters in the circuit to adjust the use of software, some parameters of the margin adjusted too low in the critical range, when the machine operating conditions in line with the software to determine the reasons for failure, then the alarm will appear.
Quick facts about NeoDen
Established in 2010, 200+ employees, 8000+ Sq.m. factory.
NeoDen products: Smart series PNP machine, NeoDen K1830, NeoDen4, NeoDen3V, NeoDen7, NeoDen6, TM220A, TM240A, TM245P, reflow oven IN6, IN12, Solder paste printer FP2636, PM3040.
Successful 10000+ customers across the globe.
30+ Global Agents covered in Asia, Europe, America, Oceania and Africa.
R&D Center: 3 R&D departments with 25+ professional R&D engineers.
Listed with CE and got 50+ patents.
30+ quality control and technical support engineers, 15+ senior international sales, timely customer responding within 8 hours, professional solutions providing within 24 hours.