Enermax EG251P-V with low 12v rails

[Agent24]

Picked up an old case for free (using it for my in-progress HTPC ) until I get a proper one

It came with an old enermax PSU - "hey this could be good" I thought...

Not wanting to risk anything, even on an enermax I decided to take a look inside, nothing seemed amiss, in fact I spotted a couple of rubycons in there

I proceeded to hook up an old (80MB) hard drive for loading and started it up. no smoke or fireworks, but 12v was sitting at 11.04 and the hard drive just didn't seem to be able to spin up fast enough to actually get going.

Checked the other rails which all seemed fine, but -12v was way out at -8.6v

Now nothing is visually wrong, all caps *look* fine (though we all know that can mean nothing) - on second look though, not all of them are rubycons for some reason... some are CTC (I think is the brand)


Any ideas on what would cause this otherwise good PSU to act in such a manner? the caps perhaps, or could it be something else?

[starfury1]

Re: Enermax EG251P-V with low 12v rails

CTC arn't what you would call great caps I dont think, even the liberties use them for DC output
one person killed them off in a year in a liberty, although I think he might have been giving it a good work out, still

So if they are being use for output get rid of them....

I have no idea of how that one put together so at a bit of a loss
could find now pics on that model here (strange he says)
Find a few on a google image search but not much use
best I could see was 339 Quad op amp

not that I think -12 is used at all these days but mostly I think it done with a 3 terminal regulator -12 rail

If you can post some pics for reference.

but more then likely someone here will know the beast
and will offer better input then I

Enermax dont build what you would call exceptionally bad supplies
so its probably worth the time to see if you can get it going properly.

it sound to me like possibly some controller regulation issue a recap my fix it I just don't know
not the guru here.

HTH cheers

Hey..... how did you go with the other thing ?
(that I've totally forgotten what it was but remembers you posting on caps ?...maybe you already replied?)

[Agent24]

Re: Enermax EG251P-V with low 12v rails

I'm running my main computer on a liberty ELT400AWT I bought 2 years ago, it's still running perfectly - let's hope it stays that way

I thought it was only the newer ones that had issues anyway?

But back to the PSU in question - I've attached a photo, hopefully it shows what you were interested in, if you want me to take anything more specific, just say.

Bottom right is your LM339, top right is LM3905 which regulates the -5v rail which is taken directly from -12, and in turn comes off of the 12v at some point, it seems.

voltage reading from the output of the +12v rectifier (STPR1020CF) showed 10v, which is probably not helpful to the state of things. Can't get a reading on the input (maybe i'm doing it wrong?)


Yeah I posted here a while ago about 2 soltek boards that wouldn't start, and had leaky GSCs.. still haven't actually got around to doing anything with them but I'll hopefully be able to start on those next week...

[gonzo0815]

Re: Enermax EG251P-V with low 12v rails

I think you may need more load at the 5v & 3.3v rail. Those PSs are group regulated, thus if there is no load at the low voltage rails, 12v will stay low.
A HDD is not considered a load of any meaning for the 5v rail.

Apart from that, if -12v is important for your setup, just check voltage before the -12v linear regulator. If it is is in the range of a little higher then -12v just replace the VR.

But sure, CTC caps can fore sure go ape shit.

[starfury1]

Re: Enermax EG251P-V with low 12v rails

actually did find some pic here but no idea of the page language think Japanese

http://chronos.mentai.org/2001/d010805_2.htm

Japanese English translation

http://translate.google.com/translat...hl=en&ie=UTF-8


here what it says on the -12V

- 12V and 5V-output terminal of the three-laden drive from奴. SECの型番はKA7905。 KA7905 model of the SEC.

here is a link to the pdf on the TOP210PFI



KA 3842A




not sure how all this slots together but there is some info for you

HTH

Cheers

[kc8adu]

Re: Enermax EG251P-V with low 12v rails

is this measured or via some onboard monitor?
remember +12 will be low with little/no load on +5

[starfury1]

Re: Enermax EG251P-V with low 12v rails

are thanks Gonzo
Edit... you too KC8

you have both posted wjile I was in the middle of doing mine...like last 3 Hr between things

Thanks

[Agent24]

Re: Enermax EG251P-V with low 12v rails

I am an idiot.

I think you're completely right, I retested it with 3 hard drives and a motherboard, +12v and -12v were both sitting happily @ 12.01v

Honestly though, I have never seen any PSU that did this before. I've run a lot with the only load being my voltmeter and they've all been fine. suppose I should remember this for next time - and here I was thinking there was something faulty with an enermax ...

Well, if you guys reckon CTC are junk I guess I should get rid of them if I plan to use this PSU... which is likely

[starfury1]

Re: Enermax EG251P-V with low 12v rails

I should have thought of that,
I was going to mention the relationship between rails
totally missed the load aspect thought with your post Doh!

If your going to replace the caps use quality stuff
you dont need to use the super low ESR (VRM type like ruby MCZ's)
but low ESR like Panasonic FC series. Ruby ZL etc
(some are water basic electrolytes like FM, not to reopen that one
but water based caps dont handle the heat as good is the discussion argument whatever, they will still work thought)

you got an RS components or Farnells near you locality, you can order from?

Yanz did a table somewhere but I cant find it

here his version 1 crude dummy loads for loading a psu

https://www.badcaps.net/forum/showthread.php?t=2400

I suppose it depends on how much of a workout its had and how much you intend to give it but check the fans OK too

Gee just re reading my first post whoa spelling mistakes everywhere...
so many disruptions to day

not a good day to try and help me thinks

HTH anyway

Cheers

[starfury1]

Re: Enermax EG251P-V with low 12v rails

OH and THANKS for the Nice big photo too

OH again
Szie of caps (diameter pitch height) as in getting the little beggers to sit flush you have to watch out for too.

[gonzo0815]

Re: Enermax EG251P-V with low 12v rails

"If it ain`t broken, don`t fix" it or similar comes to mind. So i think if the PSU does well leave the ugly CTC in there.
But sure, having some nice capacitors inside a PSU does not hurt either ;-)
Personally i am am somehow obsessive with capacitor replacement, so it certainly would not hurt to get some nice capacitors inside this Enermax.

[starfury1]

Re: Enermax EG251P-V with low 12v rails

"If it ain`t broken, don`t fix"

TRUE!
I really have to agree with that but sometimes especially if you dont want to have to strip something down later you break the cardinal rule and hope it dont BITE you!

I think you mention PVR use

if it was me I would in that case, put a decent quality fan in and look at the best possible way to shut the fan up while still getting good air flow...also I would make some sort of air filters up for the case...don't know if you can buy something like that in a case suitable for PVR use
you probably want to put it in a cabinet somewhere all hooked up so are probably not wanting to have to tear it down to often I guess

try to keep the dust bunnies down.

Cheers