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continuity between 3.33v and gnd on atx psu? Answered

Im converting my atx into a bench psu. I was checking the continuity between 5v and gnd that i connected to the LTC3780 and i got a beep (one short beep). So i checked the rest of the lines and 5v and 12v also 1 short beep. However on the 3.3v. i get  a long continuous beep.

Is this behaviour to be expected? 

thank you in advance.

4 Replies

LargeMouthBass (author)2017-09-01

If continuity is only indicated briefly, it could be the result of capacitors on the output that initially behave as a short when the test leads are applied.

I would retest each on the ohm setting rather that just a continuity check. If there are capacitors on the output (which is very commonly the case for a power suppply) then you would observe an increasing resistance value, as your ohmmeter charges the capacitors. If there is an internal short, I would expect a low resistance reading to persist.

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icey.hood (author)LargeMouthBass2017-09-08

Between gnd and 12v its rising 300+ ohm and 5v is steady at with a slight decrease between 51 and 49 ohms.. and 3v is 36 droping to 19 ohms. would this be a easy fix or shall i just get another atx if possible?

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iceng (author)LargeMouthBass2017-09-01


Understanding R C circuits is crucial to working with electronics.

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Downunder35m (author)iceng2017-09-02

Not really....
Before I started to grow up enough to start work I mostly learned electronics the other way around.
If it did not smoke it meant I made progress LOL

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