UC3842 Test Circuit
UC3842 IC can be easily found in most of the electronic equipment switching power supply. Normally whenever the power fet shorted, chances are very high that the uc3842 pulse width modulation (PWM) IC may shorted too. Although sometime you can use your meter to measure certain pins of this ic to confirm whether it works or not , i found it to be not accurate. I personally had tested some of the defective UC3842 IC where it tested good with meter but failed when on load (in circuit). In order to fully test this IC you may visit this website that talks about building your own UC3842 IC test circuit.