Friday, April 8, 2011
【 Weak current College 】 TV repair in IC testing 】
Now the electronic products often as a part of integrated circuit damage, caused or sections not functioning, affect the normal use of the device. So how do you detect IC is good or bad? typically a device with many integrated, get a defective IC equipment, first under the symptom, determines that the failure of General position, and then by measuring the fault may be parts of narrow, finally find fault.
Where to find the failure must be made through the test, usually repair personnel to use measuring pin voltage method to judge, but this can only determine the approximate location of the fault, but some pin reaction insensitive, even little reactions. In case of voltage deviations, and peripheral component damage factors must also be manifold internal fault and external fault strictly distinguish, so single * a method on the integrated circuit is very difficult to detect, and must rely on a comprehensive means of detection. Now multimeter testing, for example, a general description of the specific method.
We know that the manifold use, always has a PIN and printed circuit board "to" line is the welding flux, in circuit called ground water. Because the IC's internal use directly coupled, thus, manifold other PIN and grounding there between the foot of DC resistance, this kind of DC resistance is called the foot internal equivalent DC resistance, hereinafter referred to as R. When we get a new chipset, the via multimeter measuring pins of the internal equivalent DC resistance it is good or bad, if the pins of the internal equivalent resistance R and standard values correspond to the description of this manifold is good, on the other hand if the difference between the standard value is too large, the manifold internal damage. Measure the time it should be noted that, due to the manifold internal has a large number of transistors, diodes and other nonlinear components, the measurements of a single measured resistance also cannot determine its good or bad,you must swap sheet pen and then measuring time, access to the forward and reverse two resistance. Only when the resistance R of forward and backward are up to standard, to conclude that the manifold blocks intact.
In the actual repair, usually measured in the road. First measure their PIN voltage, if voltage anomalies, to disconnect pin wiring terminals voltage measured to determine voltage variation is caused by external components or manifold internal cause. Or you can use logging to an external circuit between the DC equivalent resistance (known as R), usually measured in the circuit of the manifold blocks a PIN and grounding feet between the DC resistance (in road resistance), R R-parallel within the total DC equivalent resistance. Often the repair will be at the road, voltage and resistance in the road measurement method. Sometimes the road voltage and resistance in the road, and deviations from the standard value is not necessarily the manifold damage, damage to the peripheral component, R, not normal, resulting in the road, voltage and resistance in the road. You can only measure the manifold internal DC equivalent resistance to determine manifold damage.
According to the actual maintenance experience in detecting IC internal DC equivalent resistance when you don't have to put the manifold from circuit welding down, voltage or road resistance anomalies feet and the circuit, at the foot of the ground is also disconnected from the circuit board and other foot to maintain the status quo, measuring out test feet and earthing pin R between forward and backward resistance values within will be judged good or bad.
For example, TV in the manifold TA7609P Rong feet in abnormal voltages or resistance, can cut off the feet and legs ⑤ rong (grounding feet) and then use the multimeter measuring suvey in rong feet and ⑤ feet measured between the resistance, a numeric, interchangeable table pen and then test it again. If the manifold measured normal to red tablefor the pen grounding 8.2 k Ω, the black table amount at the time of the grounding of 272 k Ω r equivalent resistance in DC, manifold block is corrupted. In the measurement of most pins, multimeter with R×1k, when individual pin within very large R, swap R×10k block, this is because the table R×1k retaining battery voltage only 1.5V, when manifold internal transistor series more, electricity meters in the voltage is too low, not for manifold block access to work correctly in the transistor, numerical cannot show or inaccurate.
In short, in the detection time to serious analysis, flexibility in the use of various methods, rules, do it quickly and accurately identify the failure.