About UC3842 PWM IC
This UC3842 IC is one of the most famous PWM IC use in SMPS circuit. It can be found in many electronic equipment ranging from Monitor, TV up to computer power supply. Do you know that not all part number of UC3842 can be 100% substitute with another similar part number? Lets take this for example, you found the part number of SG THOMPSON UC3842 IC have problem and your supplier give you IP3842 while others give you HA17384 and Motorola UC3842.
Do you think that all these IC spec is the same? Not really until you have tested out on the equipment you repair. I came across Monitor produced hissing sound and power blink when different number used. After putting back the exact part number, all of these symptoms gone! Now not all equipment have the same problem-you just have to test it out yourself. Hope you can learn from my experience and if possible get back the same part number.