Re-rebuilding a Sun Pro

[Pentium4]

So I recapped this thing in mid 2013, and it got about 10,000 running hours on it. I then decided I wanted to improve it some more. I became paranoid, and decided that Panasonic FR and Rubycon ZLJ might be too low ESR for this thing, so I swapped them out for nichicon PW.

Then I re-discovered something very bizarre about this PSU. It's obviously an old 5V based half bridge design. But, Sun Pro decided to use a TO-220 20A schottky for the 5V and a TO-247 30A schottky for the 3.3V and the 12V surprisingly used two 16A ultra fasts in parallel. So, I decided to upgrade the rectifiers I replaced the SB2040CT on the 5V with an S30SC4M, and replaced the two MUR16020CT's ( https://cdn.badcaps-static.com/pdfs/...e5f863bd7d.pdf ) with two MBR30H100CT's ( https://cdn.badcaps-static.com/pdfs/...4735f13e3b.pdf )
Especially per amp, the VF is insanely lower on the new rectifiers I installed. I imagine this will drastically improve the efficiency. Even though I'm not going for maximum power out of this thing, just increased efficiency, how much power do you think it would be able to do? As you can see, that secondary heatsink has got some beef to it.

I also couldn't believe that this wire didn't have any insulation on it, so I added some to it:

[c_hegge]

Re: Re-rebuilding a Sun Pro

I'd wager about 350W. You might be able to get 400 or even 450 if you upgraded the primary caps to 1000uF and gave it some 15A switchers (like 2SC3320s, for example). The primary side normally blows out first on these things anyway (at least with the 470uF primary caps and 13009 switchers that they usually come with). It looks to be a very similar (albeit somewhat beefier) design to the Thermal Master TM-420-PMSR I blew up in the last el-cheapo PSU roundup.

[Pentium4]

Re: Re-rebuilding a Sun Pro

I'd wager about 350W. You might be able to get 400 or even 450 if you upgraded the primary caps to 1000uF and gave it some 15A switchers (like 2SC3320s, for example). The primary side normally blows out first on these things anyway (at least with the 470uF primary caps and 13009 switchers that they usually come with). It looks to be a very similar (albeit somewhat beefier) design to the Thermal Master TM-420-PMSR I blew up in the last el-cheapo PSU roundup.

Yeah, you're right. It's at least the same platform. So I guess there is a decent difference between TO-220 and TO-247 package regarding the same transistor. This one has Fairchild TO-247 13009's. I made sure they were tightly screwed to the heatsink. Airflow is also a concern, since Sun Pro wisely puts the thermistor in the 3.3V toroid like you've seen. I might move it like I did on the Winsis branded one (which by the way is a super beefy version of this Sun Pro with 15A BJT's, 39 transformer, and bigger heatsinks/toroids https://www.badcaps.net/forum/showpo...postcount=1792 :

[Pentium4]

Re: Re-rebuilding a Sun Pro

This thing does really well with the new rectifers. I fired it up with a core i7 980x, x4 2gb ddr3, OC'd 9600 GSO, Intel ssd, and 2.5" hdd. While idling at 113W AC, the 12v reads a strong 12.52V. Under full load @ 225W AC, the 12v stayed at a steady 12.40v even after warming up.

[c_hegge]

Re: Re-rebuilding a Sun Pro

Don't try it in a 5V heavy PC.

[Pentium4]

Re: Re-rebuilding a Sun Pro

I don't plan on it. Although it might be interesting to see what the voltages would do. BTW, I was looking at your Thermal Master review again and on the last graph, it looks like two numbers got switched. As of right now it says the 5VSB had a 5.19A load, and read 1.04V

[c_hegge]

Re: Re-rebuilding a Sun Pro

Thanks. I've fixed that now.

[momaka]

Re: Re-rebuilding a Sun Pro

Your mods looking good as usual.

If the PSU won't be used on a 5V-heavy PC though, you could have left that 20A rectifier on the 5V rail. That will save you the S30SC4M rectifier, so you could use it on the 12V rail on a single-transistor forward PSU (since single-transistor forward don't really need to have high reverse voltage rectifiers on the 12V rail, unlike half bridge).
On the other hand, I am cheap, so don't always listen to my advice and keep rebuilding your PSUs properly as you always have .

[Th3_uN1Qu3]

Re: Re-rebuilding a Sun Pro

Don't worry about using it in a 5v-heavy computer. The 12v side of things has LOTS more tolerance than you would tend to believe, especially on the high side. Pretty much everything that can be powered from 12v has step-down buck converters, except HDD motors. And those don't give a damn if it's 10v, 12v or 14v as they have servo feedback. Things blow up when 12v is too low, overstressing the VRMs, or when the minor rails go way high, like 7v instead of 5v (yes, it does happen, and it's NASTY).

Btw, strange how noone pointed this out before - that wire is used for reinforcing the ground trace, and the PSU case is connected to earth ground and secondary ground. So it does not need insulation.

[Pentium4]

Re: Re-rebuilding a Sun Pro

Thanks. I've fixed that now.

So, I wonder if this thing with new rectifiers now has the same efficiency as yours, stock on 230V.

Your mods looking good as usual.

If the PSU won't be used on a 5V-heavy PC though, you could have left that 20A rectifier on the 5V rail. That will save you the S30SC4M rectifier, so you could use it on the 12V rail on a single-transistor forward PSU (since single-transistor forward don't really need to have high reverse voltage rectifiers on the 12V rail, unlike half bridge).
On the other hand, I am cheap, so don't always listen to my advice and keep rebuilding your PSUs properly as you always have .

Thank you! I have tons of rectifiers around, and most of them only have 45 reverse voltage. However, I did not know that STF needed less reverse voltage on the 12V. That is good to know! I even have a 60A schottky laying around that I got from an Allied (Yeah, you read that right ) So, thanks for your input.

Btw, strange how noone pointed this out before - that wire is used for reinforcing the ground trace, and the PSU case is connected to earth ground and secondary ground. So it does not need insulation.

Wow, how embarrassing of me Thanks for clarifying that for me.

The 12v side of things has LOTS more tolerance than you would tend to believe, especially on the high side.

Even on these old designs that were technically designed for 5V systems?

[momaka]

Re: Re-rebuilding a Sun Pro

Thank you! I have tons of rectifiers around, and most of them only have 45 reverse voltage. However, I did not know that STF needed less reverse voltage on the 12V.

Well, they don't "need" lower reverse voltage rectifiers, but rather they will work with them just fine.

In fact, a cheap way to upgrade a PSU (if you are all out of rectifiers) and the PSU seems decent otherwise, is to swap the 5V rail rectifier with the 12V rail rectifier. This will work best if the 5V rail is rated for more current than the 12V rail (like 30A for 5V rail and 20A for 12V rail). And the PSU must be STF, of course. Also, this mod should only be done if the PSU will be used in a 12V-heavy system.

[Th3_uN1Qu3]

Re: Re-rebuilding a Sun Pro

I have used 45v rectifiers on +12v before, even on half bridge units. A minimum rating of 60v would be preferred though.