Cheking PWM on board???

[jrd78ep]

I am troubleshooting a power supply...i found a PWM IC UC3846...any idea how to confirm that PWM IC or any type of PWM IC is working by onboard by voltage reading? I measured Vcc is ok (15Vdc) and Vref read 5Vdc. Please help...i am in new and enjoying this electronic world. Thank u guys...

 

[GreenGiant]

The only way to check if its working is to measure it with an oscilliscope and look at the waveform.

If you know what the duty cycle should be and what the peak/trough voltages are you can calculate an approximate of what your multimeter should read if you measure the output pins

 

[Rleo6965]

If you don't have oscilloscope. You can use multimeter with Frequency function. Most pwm ic run on 20khz on output pin of uc3845 and some higher..

 

[jrd78ep]

Thanks guys for sharing your knowledge...and hoping someday i can be at your level...

 

[sheldonstv]

dont forget your isolation transformer.....