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一旦ULN3839A集成块损坏,更换时须注意以下问题:(1)ULN3839A有三种,即ULN3839A-1;ULN3839A-2;ULN3839A-3。这三种IC,内部结构基本相同,各个引脚的功能相同,因此可以直接互换使用。(2)这三种IC虽说可以直接互换,但不同之处在于其脚对地之间所接中频增益调整电阻阻值不同。其阴值选取范围依次为150kΩ～∞、47～56kΩ、33～39kΩ。(3)当所更换的IC与原IC尾数不同时,更换IC后须对该调整电阻R进行更换或调整。方法是:将万用表置于2.5V档,接在脚与地之间,调整R的阻值,使脚对地电压在1.3～1.7V之间,如图1所示。例如,原机采用ULN3839A-1,而更换块为ULN3839A-2,换块后须将脚所接电阻换为47～
Once the ULN3839A manifold is damaged, pay attention to the following problems during the replacement: (1) There are three kinds of ULN3839A, ULN3839A-1, ULN3839A-2 and ULN3839A-3. These three kinds of IC, the internal structure is basically the same, the function of each pin is the same, so can be used interchangeably. (2) Though these three kinds of ICs can be directly exchanged, the difference lies in that the resistance value of the intermediate frequency gain adjustment connected between the foot and the ground is different. The negative selection range from 150kΩ ~ ∞, 47 ~ 56kΩ, 33 ~ 39kΩ. (3) When the replaced IC is different from the original IC mantissa, the adjusting resistor R must be replaced or adjusted after IC replacement. The method is: Put the multimeter in 2.5V file, connect between the foot and ground, adjust the resistance value of R, make the voltage of foot to ground is between 1.3- 1.7V, as shown in Fig. 1. For example, the original machine uses ULN3839A-1, while the replacement block is ULN3839A-2, after the block change to be connected to the resistance of the pin 47 ~