About Testing Power IC

If i come across any SMPS fault that has many bad components in it, i will not replace the components and retest the power supply. I would usually direct replace the power IC and retest the set. I don’t even test the input/signal of the power IC. The reason for it is simple, since there are so many components found to be faulty in the power supply section, chances is very the power IC will be out too.  Direct replace the power IC and the bad corresponding components could save your time of testing.

If you have not done that before, i suggest you to change your procedure of  troubleshooting SMPS and i believe you too can  see the different. However, if the complaint is no power and you did not see any burnt or bad components in it then i suggest that you perform the voltage and scope testing.

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8 Comments

1. 

   Paul

   January 25, 2010 at 3:21 pm

   Jestine,

   I had a very troublesome power supply once. The customer accidentaly shorted out FETs drain to hot ground and home fuses got blown off. I inspected the board and found rectifier bridge to be faulty and replaced it. Checked IC and although it received start-up voltage and RUN dc voltage it wouldn't put out any waveform on outputs so it was changed as well. The FET was fine. When I powered it up it stil will not put out any waveform. I inspected every single part around the IC except for SMD resistors (zener diodes, even components called 'beads')and they tested good. Then I proceded to test it with so called 'flickering method' and the meter wouldn't flicker. So I still suspect the primary side to be giving me the trouble and although I replaced IC and rectifier I'm not sure where else I should be looking for...

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2. 

   Chinedu umeano peter

   January 25, 2010 at 4:52 pm

   Hi, Mr. Jestine,am very grad about all the information u send for me,pls mr. Jestine i need one of your E-book,wherd will i get it.

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3. 

   admin

   January 25, 2010 at 8:03 pm

   Hi Paul,

   Have you scanned all the components in the primary circuit? Have you check the primary winding for shorted turns?

   Jestine

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4. 

   admin

   January 27, 2010 at 6:22 am

   Hi Chinedu,

   You can get it from the website (using credit card) or by using western union services. Please email me at jestineyong(at) electronicrepairguide.com if you have other question-thanks!

   Jestine

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5. 

   Ahmed

   February 3, 2010 at 9:45 am

   hi am tecnian for tv dvd monitor and etc i have been dowing till 1992 am ok but sometime i seen some hard trouble like standpy for tv most of them is sony tv when u swich it goes standpy and lite is flashing 4 time sme time 9 time so what is the most trouble shooting off standpy probles for u r exprience

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6. 

   admin

   February 3, 2010 at 4:33 pm

   Hi Ahmed,

   Yes you are right. I have seen Sony Monitor with vertical IC dry joints also cause the power to blink (few times). Guess we need to make sure the secondary side components and circuits are good before checking the stand by area.

   Jestine

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7. 

   Dariush Salami

   December 10, 2012 at 10:52 am

   hi,i have sony mother board vgn-s28g9 and it dosnt power on,how can i fix it?i dont have 3,3v on power switch

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   • 

     Jestine Yong

     December 11, 2012 at 6:40 am

     HI Dariush,

     Sorry no info on this. When you say no 3.3 volt then try trace backward to see if there is any 3.3 volt voltage regulator that had broken down.

     Jestine

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