Hey, I know this was posted a little more than a year ago, but I just stumbled across this.

First off, that power supply is a fake/copycat Delta Electronics PSU. The real Delta supplies are constructed much better than this one, and are much more reliable as well.

That PSU you have there, judging by the generic looking construction, probably is only good for about 200W to 250W maximum. Maybe 300W on a good day. Those cheap PSUs almost always lie about their power output capability!

Also, here is the important bit:
Beware when you find only one of the voltage-doubler caps failed, as you did here.

It fails either because the voltage across the voltage-doubler capacitors has become unbalanced, or it is just a regular low-quality capacitor (or it is old). When the voltage becomes unbalanced, it causes one capacitor to get too much voltage. This can happen when one of the bleeder resistors goes open-circuit. Be sure to check that, otherwise it might fail again!

I know this because I helped someone on an electronics forum fix their misbehaving PSU. One of the voltage-doubler caps had failed, and when they replaced it, the problem resurfaced a few weeks later - the new capacitor was now bulged as well! After thinking about it, I had the sudden realization that it could be the bleeder resistor had failed (open-circuit), and indeed it was! 🙂

Also, another cause of voltage imbalance could in fact be the OTHER capacitor! I know, it sounds weird, but get this:
When the leakage current in one capacitor becomes too high, it can cause the other capacitor to get too much voltage! Capacitors that read abnormally high in capacitance, often (if not all the time) have an excessively high leakage current. The extra leakage current simply makes it take longer to charge up, hence the high capacitance reading. You can try this for yourself with a known good capacitor, by placing a resistor in parallel with the capacitor being tested. (The resistor can be anywhere from 10K to 1M or more. It depends on the current your capacitance meter puts out.)

I bet you've come across this kind of a failure before, seeing as all of you repair so many items. But I just thought you'd like to know, in case you didn't know already. 🙂

Cheers,
-Ben

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Hi Humberto, Yes that nice Power Circuit TestBench Adapter should easily work. But since even the 3.3 Volt Output can generate High Currents up to 25 Amps or more, be Carefull not to Short Circuit your Lab equipment. Or maybe use some kind of Current Limiter inbetween your Test Lab Power Supply and your Devices you want to repair. Afterall 500 Watt is Current Overkill I guess?
I wouldn't want you to destroy anything by blowing away those thin Copper Layers to Kingdom Come. Maybe I've also some easy Current Limiter Circuit laying around here somewhere.
Albert.

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Thanks Gerald.

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Well Albert, if you repair it, let us know and post it in this blog.

By the way, you sent to me by means of Mr. jestine Yong a project with a PC SMPS, and I'd like to use this 500 watts SMPS to do it. Thanks.

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Yes Waleed, I really want to use it as a DC Power Supply for appliances which need to be repaired.

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Thanks Robert.

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