Power supply build quality pictorial. part 2

[goodpsusearch]

Re: Power supply build quality pictorial. part 2

I can list many psu manufacturers that use schottky (or ultra fast recovery) rectifiers in parallel. It is done to improve efficiency and decrease heat.

[momaka]

Re: Power supply build quality pictorial. part 2

Its generally not a good idea to do that.

Yes, it would double the current capacity.

BUT! Since no two things are alike, one will have a smaller voltage drop than the other, causing the other to handle more current. When it handles more current, it's forward voltage drop decreases, causing it to handle more current! Once the diode gets out of it's max SOA temperature, it will self destruct from within a few minutes, to only a few millis. This domino effect is called 'thermal runaway'.

Using two diodes in parallel is just asking for failures!

But that's assuming the current draw across the diode(s) is very high (as in higher than what each diode can handle individually) and that the diodes aren't attached to a heat sink.
When they are attached to a heat sink (as is almost always the case), the temperature difference between the two diodes won't be more than a few degrees apart. So if the diodes are of very similar spec, the current distribution going across each will be fairly even.

I can list many psu manufacturers that use schottky (or ultra fast recovery) rectifiers in parallel. It is done to improve efficiency and decrease heat.

The improvement in efficiency and decrease in heat is only very slight.

[Pentium4]

Re: Power supply build quality pictorial. part 2

Really disappointed with these Sparkle power supplies. It only had a 220uF 16V OST cap and a 2200uF 16V Teapo cap for 12V filtering so I replaced the 220 with a 470 and the 2200 with a 3300. Still doesn't seem like it'd be enough for 264W of continuous 12V. This one I just recapped and the thing looks great but it sends out 12.8V on the 12V, the other rails are perfect. I had another Sparkle that was same design but a 350W and the 5VSB failed, I recapped it and it started working but sends out exactly 13.00V on the 12V. What the hell is wrong with these stupid things???

[Wester547]

Re: Power supply build quality pictorial. part 2

Really disappointed with these Sparkle power supplies. It only had a 220uF 16V OST cap and a 2200uF 16V Teapo cap for 12V filtering so I replaced the 220 with a 470 and the 2200 with a 3300. Still doesn't seem like it'd be enough for 264W of continuous 12V. This one I just recapped and the thing looks great but it sends out 12.8V on the 12V, the other rails are perfect. I had another Sparkle that was same design but a 350W and the 5VSB failed, I recapped it and it started working but sends out exactly 13.00V on the 12V. What the hell is wrong with these stupid things???

If there's room for an extra 2200uF or 3300uF 16V capacitor on the 12V rail that may help (I would recommend 2 * 2200uF, or 4400uF, as the minimum on the 12V rail). I don't think that 220uF 16V capacitor is for the 12V rail, though. I think it's for the -12V rail to be that small. In any case, something else may be wrong, though I think it's hard to say what. 2200uF/3300uF may be okay for the 12V rail depending on what its rectifier is capable of, though crossloading of any sort may be ill-advised at that point.

[Pentium4]

Re: Power supply build quality pictorial. part 2

If there's room for a extra 2200uF or 3300uF 16V capacitor on the 12V rail that may help (I would recommend 2 * 2200uF, or 4400uF, as the minimum on the 12V rail). I don't think that 220uF 16V capacitor is for the 12V rail, though. I think it's for the -12V rail to be that small. In any case, something else may be wrong, though I think it's hard to say what. 2200uF/3300uF may be okay for the 12V rail depending on what its rectifier is capable of, though crossloading of any sort may be ill-advised at that point.

Yeah I forgot to specify, those 2 caps for the +/- 12V. There is room for more caps on the secondary, I can see if they go to the 12V. Do you think that that could possibly lower the 12V reading? And also, the -12V reads high as well at -12.43V

[mariushm]

Re: Power supply build quality pictorial. part 2

The 12v should go down once your computer puts some load on the 5v - typical for group regulated power supplies. -12v doesn't matter anymore. It's only used by some obscure SCSI controllers on PCI slots and by the serial or parallel ports which I doubt you use.

I was assisting a guy on a forum complaining about his system restarting randomly - he was looking for a new power supply and I told him "hey, open it up, maybe it's just something simple to fix"

Here's what he posted:



It's a Tagan 530w ... the 22uF 400v pfc cap and the 4700uF 10v (probably on 5v rail) going bad.... Capxon GL series.

Later that day he told me he started Diablo 3 and the power supply started to burn... probably some electrolytic burning up.
He's too scared to fix it anymore.

[Pentium4]

Re: Power supply build quality pictorial. part 2

The 12v should go down once your computer puts some load on the 5v - typical for group regulated power supplies. -12v doesn't matter anymore. It's only used by some obscure SCSI controllers on PCI slots and by the serial or parallel ports which I doubt you use.

I was assisting a guy on a forum complaining about his system restarting randomly - he was looking for a new power supply and I told him "hey, open it up, maybe it's just something simple to fix"

Here's what he posted:



It's a Tagan 530w ... the 22uF 400v pfc cap and the 4700uF 10v (probably on 5v rail) going bad.... Capxon GL series.

Later that day he told me he started Diablo 3 and the power supply started to burn... probably some electrolytic burning up.
He's too scared to fix it anymore.

Yep, you're right. I just tested that right before I read your post and once I upped the 5V usage, they both dropped to 12.44V and 12.39V, perfect!!! Oh man, no wonder he was having issues! That thing has a nice sized heatsink though.

[goodpsusearch]

Re: Power supply build quality pictorial. part 2

The 12v should go down once your computer puts some load on the 5v - typical for group regulated power supplies. -12v doesn't matter anymore. It's only used by some obscure SCSI controllers on PCI slots and by the serial or parallel ports which I doubt you use.

I was assisting a guy on a forum complaining about his system restarting randomly - he was looking for a new power supply and I told him "hey, open it up, maybe it's just something simple to fix"

Here's what he posted:



It's a Tagan 530w ... the 22uF 400v pfc cap and the 4700uF 10v (probably on 5v rail) going bad.... Capxon GL series.

Later that day he told me he started Diablo 3 and the power supply started to burn... probably some electrolytic burning up.
He's too scared to fix it anymore.

Tagan 330W with all of its caps bad:
https://www.badcaps.net/forum/showthread.php?t=12484

[Behemot]

Re: Power supply build quality pictorial. part 2

-12v doesn't matter anymore. It's only used by some obscure SCSI controllers on PCI slots and by the serial or parallel ports which I doubt you use.

You mean many old but still good sound cards, right?

That Sparkle is basially some kind of Fortron FSP300-60xxx. If the +12V rail would go too high even with load on +5 V, I think that orange potentiometer could be used to manually regulate it down.

[Agent24]

Re: Power supply build quality pictorial. part 2

Since when did Parallel ports use -12 volts?

[mariushm]

Re: Power supply build quality pictorial. part 2

Since when did Parallel ports use -12 volts?

Ignore that. I wrote it early in tne morning after a night without sleep.

I don't know where I read that on some systems it used to be -5v and 5v, probably before the parallel port modes were standardized.... but I may be completely wrong in this particular case.

Oh yes... ISA slot also used -12v ... I guess some audio amps on ISA and PCI sound cards did use split power supply designs or something like that, using both +5v and -5v or +12v and -12v... but -12v was never a high current rail... it was 1-2 amps most of the time.

[goodpsusearch]

Re: Power supply build quality pictorial. part 2

but -12v was never a high current rail... it was 1-2 amps most of the time.

Or less...

[tom66]

Re: Power supply build quality pictorial. part 2

Serial ports use -12V. Aside from soundcards, they are the only interface to use them it appears.

[Behemot]

Re: Power supply build quality pictorial. part 2

Or less...

But you don't need much on soundcard, there are never powerfull opamps anyway. That's the reason why you need not only good sound card, but also good reproductors or even standalone amplifier for good sound.

ADD// -12 is directly on first pin of PCI slot

[momaka]

Re: Power supply build quality pictorial. part 2

But you don't need much on soundcard, there are never powerfull opamps anyway. That's the reason why you need not only good sound card, but also good reproductors or even standalone amplifier for good sound.

That's because you haven't tried one of those older Yamaha YMF724 PCI sound cards. Some of them IIRC have a TDA1517 for the output - that chip is rated for 6W per channel. You can actually power a small set of desktop speakers without an amplifier from that sound card. And the sound is also very good too because of the Yamaha XG chip. I have one and I love it.

[ben7]

Re: Power supply build quality pictorial. part 2

Found this while browsing, and, DAMN!

http://under-your-skin.com/jdxnc/blowncap1.jpg

[Pentium4]

Re: Power supply build quality pictorial. part 2

Found this while browsing, and, DAMN!

http://under-your-skin.com/jdxnc/blowncap1.jpg

Wow, that's CRAZY!!!!!

[tom66]

Re: Power supply build quality pictorial. part 2

I think that's what happens when you switch it from 230V to 115V.

[Pentium4]

Re: Power supply build quality pictorial. part 2

I think that's what happens when you switch it from 230V to 115V.

If it was a PSU using YC caps, then it deserves it

[Agent24]

Re: Power supply build quality pictorial. part 2

Wow, that's CRAZY!!!!!

Crazy?

There's a much better photo (I think on this forum somewhere) of a CapXon primary that incinerated itself...