Enermax PSU 431 Watt blew up!

mcrites · Jan 8, 2002

Recently, I just turned on my computer and heard a pop come from my psu. It blew out one of my rheostats when this happened as well. I took a piece of wire and shorted the two pins to make sure it was the psu, and it would not turn on

I was wondering if someone might be able to shed some light on what may have happened since this is quite an expensive little psu

I am thinking of running to CompUSA and getting their antec 400W to replace it. Thanks for your help

Hoot · Jan 8, 2002

There's a little "chicken and egg" relationship here. Did a malfunctioning rheostat kill your PSU, or did a malfunctioning PSU kill your rheostat? Troubleshooting after-the-fact, is difficult. You can kill a rheostat by pumping too much current through them, but you often kill whatever it was controlling also. If the rheostat resistive element shorted out to its housing, it would short the +12V output from the PSU to ground and that could kill the PSU. Admittedly, most PSUs have overcurrent (load short circuit) protection in them. As is often the case with a post mortem examination, all you can really determine is that it is dead. The Antec 400W is a good PSU, but then the Enermax you had was a good PSU also. If I was in your shoes, before I hooked up an expensive replacement PSU to a system that may be in a position to kill it also, I'd try some cheapo PSU first.

73, Hoot

mcrites · Jan 8, 2002

This rheostat has been working fine for a while, I just assumed it was killed by the psu

It was weird, I just turned it on and heard that part and no more psu

How can I tell before I turn on the psu to power everything, if something might kill the psu? I know this is probably more chicken and the egg, but I hope there is an answer

flounder43 · Jan 8, 2002

I think it is more likely that a faulty rheo would kill the psu than the other way around.

What Hoot was saying is that if you are going to put another expensice psu on that system, try a cheapy first, to make sure there is not some other short somewhere...

Maximus Nickus · Jan 8, 2002

Or plug in a old 486-PSU into it if you have one lying around

mcrites · Jan 8, 2002

if there is a short in the system, would it not power up at all?
Edit:
Nevermind I wasn't thinking or reading properly yesterday. Hoot, I understand now what you mean about the rheo shorting out now, and I am beginning to wonder about the rheostats I have been purchasing from caseetc. I have 2 of them die on me now. You guys think I should just punt up the money for some good 12W rheostats from allied electronics: www.alliedelec.com or should these 5W rheos from caseetc be fine? Thanks for all your help.

mcrites · Jan 9, 2002

Hoot, at allied electronics they have their 25W and 50W UL approved, but not their 12.5W, I was wondering if the 25W would be a better to get since of this, maybe it wont short out?

Also, should I get 25, 50, or 100 ohms? The 5 watt ones I have are 100 ohms I believe.

Hoot · Jan 9, 2002

The 25W is a better investment from a reliability point of view. I would recommend 25 Ohms, but 50 or 100 is okay also. I will go to the local Electronics Surplus store in a day or two and see how many of those 25W 100 Ohm units they have left. I know they are at least 50% less than Allied wants. I'll pick up all they have left and turn them around to all who need them for cost.

73, Hoot

Hoot · Jan 9, 2002

Well, I just got back from the Electronics Surplus store. Picked up some more of the 100 ohm 25W rheostats and stumbled upon a box full of Ohmite 35 ohm 12.5W (Nice) rheostats, for a very reasonable price. I don't mind picking some up for people, but I don't think discussing cost is appropriate here. So, I will post in the Classifieds under Cooling Parts, and/or you can PM me if you don't have Classified priveleges yet.

73, Hoot

Randy · Jan 9, 2002

Mcrites, before you write that psu off and if you haven't checked it already, open it up and see if the fuse is blown. I shorted my enermax eg365p and it was dead. I checked the fuse and it was blown after replacing the fuse it works as good as ever.
Randy

Hoot · Jan 9, 2002

I thought about that yesterday, but assumed he checked that.

73, Hoot

mcrites · Jan 9, 2002

Heh, I dont how to replace it, im stoopid

mcrites · Jan 9, 2002

Hoot, I saw an earlier post you made once about building a voltage regulator and just using a pontentiometer to regulate the voltage from that or some such. I was wondering if that was a better solution, no monetary problems involved, or is it better to get these higher rated rheostats and use that? I am starting to do research on the voltage regulators atm, but hopefully you can point me in the right direction

Hoot · Jan 9, 2002

The three terminal regulator is an easy to implement solution, with only one flaw. You can not turn the fan speed up to full, even if you want to, without bypassing the circuit. For that reason, I went with a rheostat, despite it not being as efficient a solution.

73, Hoot

mcrites · Jan 9, 2002

Hoot, thanks for all your help, I will pm you about the rheostats you got. I have a question for ya once again? If what you say may be true and the grounding of the rheo by its casing killed my psu, how can I tell if another rheo would do that as well? As you know, I am apprehensive about killing more power supplies

Im just trying to cover all my bases so I wont fry another

Randy · Jan 9, 2002

mcrites, I sure hope you didn't think I was implying that you were
didn't know what you were doing as that was not my intent at all. I was just asking that you check it if you had not already. Sometimes the small things get overlooked.

Randy

mcrites · Jan 9, 2002

Randy said:
mcrites, I sure hope you didn't think I was implying that you were
didn't know what you were doing as that was not my intent at all. I was just asking that you check it if you had not already. Sometimes the small things get overlooked.
Randy

Heh, no offense taken, I was joking

Hoot · Jan 9, 2002

mcrites said:
Hoot, thanks for all your help, I will pm you about the rheostats you got. I have a question for ya once again? If what you say may be true and the grounding of the rheo by its casing killed my psu, how can I tell if another rheo would do that as well? As you know, I am apprehensive about killing more power supplies Im just trying to cover all my bases so I wont fry another

And for good reason. "Once bitten, twice as shy". Quality Rheostats are built around a ceramic form. It doesn't melt and it is nye impossible to make one fail in such a way as to contact the mounting shaft. A flashover of greater than 4000 volts might though. I've done it, It's not pretty.

73, Hoot

mcrites · Jan 10, 2002

Hoot said:
A flashover of greater than 4000 volts might though. I've done it, It's not pretty.

73, Hoot

Hehe, I would be afraid to even be around 4000 volts.

Looks like these must be subpar then.

Enermax PSU 431 Watt blew up!

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