Wednesday, March 9, 2011
Weak current College】 【IC testing common sense】.
<br> <br> 1. pre-test to understand integrated circuit and its associated circuit works. <br> Check and repair before the first integrated circuits to become familiar with the IC features, internal circuit, the main electrical parameters, the role .of the PIN and the pin of the normal voltage, waveform and peripheral components circuit works. If you have the above conditions, analysis and inspection lot easier. <br> <br> 2. test do not short circuit caused the PIN. <br .> Voltage measurement or testing using oscilloscope filter probes, table when the wave or not due to sliding probes and IC pin short-circuit, preferably with pin direct connectivity of printed circuit for measurement. Any moment of short-circuit are easily damaged circuits, test .flat package CMOS IC to be cautious when. <br> <br> 3, is strictly prohibited without isolating transformer SBK-750VA band steel, using test equipment has been grounded to touch base with live TV, audio, video, and other devices. .<br> Forbidden shell has grounded equipment directly test without power isolation transformer function module ABL8PRP24100 TV, audio, video, and other devices. Although General Recorder has a power transformer, when exposed to a special especially output power is large and the nature of the .power used is not very aware of the TV or audio device, it is first necessary to ascertain whether the machine chassis, otherwise easily charged and backplane with live TV, audio, and other equipment power supply circuit, spread to the integrated circuit, causing the .problem. <br> <br> 4, it is necessary to pay attention to the performance of insulated electric iron. <br> Do not allow welding of live using a soldering iron, to confirm the soldering iron does not live, it is best .to put the soldering iron shell grounding, MOS circuit should be careful to use 6 ~ 8V of low voltage circuits rail is more secure. <br> <br> 5, to ensure that welding quality. <br> Welding, soldering and welding indeed .accumulation, stomatal easily soldered. Welding time is less than 3 seconds, the application of power in the searing heat around 25W. Welding fine integrated circuits to look, it is best to use an ohmmeter measure the PIN megohmmeter ZC25-3500V1000V has short circuit between ., confirm that no solder adhesion phenomenon and then power on. <br> <br> 6. do not easily conclude that the integrated circuit is damaged. <br> Don't judge the integrated circuit has been corrupted. Because the vast majority of .the direct coupling of integrated circuits, once a circuit is not working properly, can result in multiple voltage changes, and these changes are not necessarily integrated circuit damage caused, in addition, in some cases the PIN voltage measured and consistent with the normal or near .-time, and not necessarily indicative of the integrated circuit is good. Because some soft failure does not cause change of DC voltage. <br> <br> 7, testing instruments and internal resistance. <br> DC voltage measurement IC pin, you .should choose the ammeter is greater than 20 K Ω / v multimeters digital multimeter battery 15V, otherwise the parties certain pin voltage will have greater measurement error. <br> <br> 8, it is necessary to pay attention to the thermal power IC. .<br> Power IC should dissipates, does not permit without heatsink while at high power of the State. <br> <br> 9, lead to reasonable. <br> As required by the IC's internal external components in place of the damaged part ., should use small components, and connection to reasonably so as not to cause unnecessary parasitic coupling, especially to handle audio amplifier IC and preamplifier circuit between the grounding port. <br> <br>.