Common fault Of IC Voltage Regulators
Those days you could only see the common 3 legs 78 and 79 series of voltage regulator ICs in circuit boards but now it is common to see IC voltage regulators that have more than 5 pins. Some have single output and some have multiple output voltages. The common fault for a voltage regulator IC are:
- Shorted IC
- No output voltage
- low output voltage
- a too high output voltage and
- IC breakdown when under load
Finding the IC problems on 1 to 4 is not difficult but locating the IC that breakdown under load will be a bit difficult but unless you know what to do. Lets take a power LED blinking problem in an equipment as example. For your information most power LED signal source is coming from a microcontroller (MCU) chip. If you get a good supply voltage to the IC voltage regulator and fluctuate output you will know that either the IC or the mainboard circuitry have problem. The problem now is that when you lifted up the output pin of the ic voltage regulators you will see that the output voltage is back to normal and ths will promt you thinking that the mainboard or the circuitry have problem. The actual fact is that the ic voltage regulator itself can't sustain the current draw from the mainboard.
You can confirm if the ic voltage regulators is good or bad by substituing a working one or use an automobile bulb to test it. A good IC should produce a steady light and bad one will not have any light or blinking light.