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Products => Test Equipment => Topic started by: kgavionics on August 02, 2020, 08:28:18 pm

Title: Testing Integrated circuits using only a Multimeter!!
Post by: kgavionics on August 02, 2020, 08:28:18 pm

Hi guys
I'm troubleshooting a TV Power supply board, tested all the discrete components which were ok. Now, I think that the main SMPS main circuit is the culprit, because it's resistance between the VCC to ground is aournd 200 kohms! I'm not sure though! I used to have an oscilloscope and it would have been very easy to probe the output of the circuit and see the waveform! But now I only have a MM (Brymen BM-869S) and I'm wondering how to be sure that an IC is not working in a particular board?
Thank you in advance!

Title: Re: Testing Integrated circuits using only a Multimeter!!
Post by: CDaniel on August 02, 2020, 08:54:41 pm

That resistance is very high , not an indication that the IC is bad . It could be bad but not for this reason .
For repair the scope has very little use , because the SMPS controllers have protections triggered by multiple faults and in many cases won't output anything for you to see the  waveforms .
Usually if all parts in  the secondary and primary seems good , no shorts , no dried electrolytic caps , than the logical step is to replace the controller and see if this solve the problem or you have to check more the components .