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PWM IC Testing Method
Today I want to share about External Voltage Test Method for TL494 PWM IC. I found this method in Mr Jestine Yong’s Switch Mode Power Supply E-Book. I have applied this method in one of my customer’s working SMPS and would like to share how this checking on PWM IC can be done. First download the IC datasheet and find out which pin is the VCC, ground and output.
Once you have identified the pin outs you can start to connect the 12V DC power supply to TL494 IC VCC pins and pin No.7 (Ground) or 0V.
I hooked-up my Precise Test Lead Adaptors with IC’s Pins and powered them with my DC Variable Power Supply and connected my Handheld Oscilloscope Meter’s UNI-T UT812B positive probe to IC’s pin No. 8 & 11 and black probe was connected to DC Variable Power Supply Ground Lead.
As seen in above picture the red test clip is connected to TL494 IC’s Pin No.12 and black test clip is connected to Pin No.7. My hand was holding the positive test probe of my Handheld Oscilloscope and black probe is connected to DC Variable Power Supply Ground Lead.
As seen in the above picture was the PWM waveforms and frequency. This indicates the PWM IC is working fine. If you came across a situation where you can’t get the waveform even tested it off board this suggest that the PWM IC is already bad and need replacement. If you understand well about an IC from the IC datasheet this means you can always follow the method above to check if the IC is working or not. I liked Jestine Yong testing methods and fully recommend his SMPS Repairing E-Book to all repair techs.
This article was prepared for you by Owais Akhter from Muscat Oman.
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