1. In-circuit detection This method is performed when the ic is not soldered into the circuit. In general, a multimeter can be used to measure the positive and negative resistance values ​​of each pin corresponding to the ground pin, and compared with the intact ic. .
Second, in the road detection This is a multimeter to detect the ic pin in the road (ic in the circuit) DC resistance, ground AC voltage and total operating current detection method. This method overcomes the limitation that the replacement test method needs to replace the ic and disassemble the ic, and is the most common and practical method for detecting ic.
1. DC working voltage measurement This is a kind of measurement of the DC supply voltage and the operating voltage of the peripheral components by the multimeter DC voltage block under the condition of power-on; detecting the DC voltage value of each pin to ground and comparing it with the normal value, and then Compress the fault range and get the damaged component out. Pay attention to the following eight when measuring:
(1) The multimeter should have a large internal resistance, which is less than 10 times the resistance of the circuit under test, so as not to cause a large measurement error.
(2) Usually, each potentiometer is rotated to the middle position. If it is a TV set, the signal source should use a standard color bar signal generator.
(3) The test leads or probes should be anti-slip. It is easy to damage ic due to any short circuit. The following method can be used to prevent the pen from sliding: take a valve core of the bicycle and set it on the tip of the watch, and grow the tip of the watch to about 0.5mm, which can make the tip of the watch be in good contact with the tested point, and can effectively prevent slippage. Even if it hits an adjacent point, it will not short-circuit.
(4) When the measured voltage of a pin does not match the normal value, it should be analyzed according to whether the voltage of the pin has a significant influence on the normal operation of ic and the corresponding change of other pin voltages, and the ic can be judged.
(5) The ic pin voltage is affected by peripheral components. When the peripheral components are leaking, short-circuited, open-circuited or variable, or the peripheral circuit is connected to a potentiometer with variable resistance, the position of the potentiometer sliding arm is different, which will change the pin voltage.
(6) If the voltage of each pin of ic is normal, it is generally considered that ic is normal; if the voltage of the pin of ic is abnormal, it should start from the maximum deviation from the normal value to check whether the external components are faulty. If there is no fault, ic is likely to be damaged. .
(7) For dynamic receiving devices, such as televisions, the voltage of each pin of ic is different when there is no signal. If it is found that the pin voltage does not change, the change is large, and the ic damage can be determined by the change of the signal size and the different positions of the adjustable components.
(8) For devices with multiple working modes, such as video recorders, the voltage of each pin of ic is different under different working modes.
Also add two:
2. AC working voltage measurement method In order to grasp the change of ic AC signal, the AC working voltage of ic can be approximated by a multimeter with db jack. When testing, the multimeter is placed in the AC voltage block, and the positive pen is inserted into the db jack. For the multimeter without the db jack, a 0.1~0.5μf DC blocking capacitor needs to be connected in series with the positive pen. This method is applicable to ic with lower operating frequency, such as video amplification stage and field scanning circuit of TV sets. Since the natural frequencies of these circuits are different and the waveforms are different, the measured data is an approximation and can only be used for reference.
3. Total Current Measurement This method is a method for determining the quality of an ic power supply by detecting the total current of the ic power supply. Since most of the ic is directly coupled, when the ic is damaged (such as a pn junction breakdown or open circuit), it will cause the latter stage to be saturated and cut off, causing the total current to change. Therefore, by measuring the total current, the ic can be judged as good or bad. It is also possible to measure the voltage drop of the resistor in the power path and calculate the total current value using Ohm's law.
A manual pulse generator (MPG) is a device normally associated with computer numerically controlled machinery or other devices involved in positioning. It usually consists of a rotating knob that generates electrical pulses that are sent to an equipment controller. The controller will then move the piece of equipment a predetermined distance for each pulse.
The CNC handheld controller MPG Pendant with x1, x10, x100 selectable. It is equipped with our popular machined MPG unit, 4,5,6 axis and scale selector, emergency stop and reset button.
Manual Pulse Generator,Handwheel MPG CNC,Electric Pulse Generator,Signal Pulse Generator
Jilin Lander Intelligent Technology Co., Ltd , https://www.landermotor.com