Top Selected Power TOP-350XP

[Pentium4]

These things are awesome...one of my favorite designs for old units. It really bugs me that Topower always used garbage caps. It pains me to think that the only reason these well designed units will be chucked in the trash is because the caps fail, so it makes my day to save one. As you can see, the caps in this unit were not in good shape! It was made some time in mid 2004.

To make a long story short, every cap in the unit tested bad except the bulk caps, BJT drive caps, daughterboard caps, and -12V rail caps. The CS caps that spewed their guts were both on the 5V rail. The CS 1000uF 10V 5VSB filtering cap that didn't bulge read: 468uF, 1.5Ω.

This thing got a full recap except for the bulk caps. The bulk caps read: 668uF 0.14Ω, and 652uF 0.14Ω. Amazing how those things can hold up so well from bad brands.

The only other thing I changed was the 100Ω resistor on the 5V rail to 200Ω, and heatshrinked it

The sleeve bearing fans surprisingly had grease left in them. I still added a drop of oil to them.

This thing is currently powering my room's HTPC. It had a recapped Corsair CX430, which I pulled to put in a gaming rig I am building. This PSU only has two 10A ultra fasts on the 12V but it doesn't have to power much. Just a Pentium 4 661 (3.60GHz) 65W TDP version (D0) 4GB RAM, single HDD, fanless Radeon HD 4670.

I will post some of the cap information later, because it is somewhat interesting

[Pentium4]

Re: Top Selected Power TOP-350XP

After working on it. While streaming 720p video, the 12V rail sits at 11.97V

[everell]

Re: Top Selected Power TOP-350XP

Well built "old" design antique using TL494 pwm chip

[Wester547]

Re: Top Selected Power TOP-350XP

That conductive glue is more appalling than the blown capacitors.

I'm not sure if it's capable of 350W with those 2SC2625 bipolar transistors and only two 10A ultrafasts (but it looks like they're mounted next to one another rather than on opposite ends of the heatsink, which means they are more likely to be capable of 20A). Possibly 300W. I don't like that the primary heatsink is touching the primary capacitors (the primary heatsink can dissipate some heat in half-bridge topology), and that the secondary side isn't receiving much airflow between the overarching heatsink and that bundle of wires. No surprise the CS capacitors (and what looks to be a lone Fuhjyyu?) gave up, along with the fact that this unit is 12+ years old. The input capacitors in a voltage doubler last even from shoddy brands because A) they are much larger so they can dissipate heat better and dry up slower, as they are impregnated with more electrolyte than smaller caps and have larger seals, B) they aren't really under much stress as they're only smoothing and filtering 100-120Hz ripple and not 50-100KHz+ ripple, and C) the electrolyte is formulated a bit differently in high voltage caps, with a higher concentration of organic solvent rather than H2O so they are less prone to generating H2 (Hydrogen Gas).

That's a nice power supply overall, though. Good job on the repair. Interesting how despite that it's a half-bridge PSU, there appears to be a UC3842B IC on the primary side - possibly for +5VSB? Rather than heatsink the bridge rectifier, I think that money could have been better spent elsewhere, possibly on beefier switchers or output rectifiers.

P.S. I spy with my little eye... bad G-Luxon(?) in the background.

[Pentium4]

Re: Top Selected Power TOP-350XP

This thing could easily do 350W. Remember the MPT-301 that c_hegge reviewed? It did 350W with 2SC2625's, with a tiny heatsink! The heatsink in this Topower is huuuuuuge compared to this Macron: http://www.hardwareinsights.com/wp/t...-Power-MPT-301

I was actually going to put two 16A or 20A rectifiers in this unit but I could not find my bag of rectifiers and figured that the ones it has would be good enough for the application. I'm sure the PSU is super happy with the new caps

[Wester547]

Re: Top Selected Power TOP-350XP

Well, I'm sure it can do 350W at 220V-240V. 120V I don't know, but c_hegge never tested those PSUs for more than 1 hour (approximately, 10 minutes per load). I'm sure it could do 350W @ 25ºC ambient at 120V, for a little while. Not sure if it would be capable of that at higher ambient temperatures with 24/7 use, but it's probably never going to see such a high load for long so for your purposes, it will work fine. How much it can do would also highly depend on how well the bipolar transistors are driven and if their thermal pads are in good shape.

Another reason I'm a bit doubtful is those older half-bridge Huntkey units, even with 120mm-140mm fans and large heatsinks, were known to explode at their rated wattage (350W-550W), even with 13009s (TO-220 and TO-3P) and 2SC3320s, an overspec'd secondary, and huge input lytics... especially if ran above ambient temperature. I suppose that's a bit of an apples to oranges comparison as this isn't a Huntkey PSU. If the primary heatsink and BJTs stay cool, it's theoretically possible to pull even more than 350W. Unique managed to pull 650W with 13009s and an 80mm fan, at 35ºC ambient, because of a hugely overspec'd secondary side.

[Pentium4]

Re: Top Selected Power TOP-350XP

Yeah, the higher mains does help a bit. But those heatsinks could soak up quite a bit of heat. Especially with a fan blowing right over the top of it. The other PSU that c_hegge reviewed which was based on the same design with 2SC3320's managed 500W.

http://www.hardwareinsights.com/wp/g...saf450-review/

Ideally though, you would want some beefier 12V silicon. Not sure why they couldn't even spring for two 12A ultra fasts, which would even make a difference.

[Wester547]

Re: Top Selected Power TOP-350XP

The Huntkey Balance King 5000 managed 500W with 2SC3320s as well, in accordance to Hardware Secrets' testing methodology:

http://www.hardwaresecrets.com/huntk...pply-review/7/

This is thanks to both rather overspec'd output rectifiers and the addition of APFC, which both units share (the latter). As an aside, schottky rectifiers would be even better than ultrafasts. But I don't think the transformer design would permit for that since they used ultrafasts by default. They probably used 10A ultrafasts to... wait for it... reduce the cost of manufacturing.

[Pentium4]

Re: Top Selected Power TOP-350XP

P.S. I spy with my little eye... bad G-Luxon(?) in the background.

Hahaha, forgot to respond to this. They are indeed G-Luxon, original ones. They were on a Socket 478 motherboard made in early 2004. They had roughly 38,000 hours on them. They tested good but I replaced them with nichicon PW because I am taking the machine up north to my brother to use as a file server. Will be powered by the highest end CWT ISO series I've seen. The G-Luxon tested good by the way.

Wow! I think that is the first time I have ever seen APFC in a half bridge PSU that wasn't a piggy back board

I will post more pictures, but here are the ones from the 5V rail:


I believe "LOW ESR" is false advertising at this point in time

[Wester547]

Re: Top Selected Power TOP-350XP

They had roughly 38,000 hours on them. They tested good but I replaced them with nichicon PW because I am taking the machine up north to my brother to use as a file server. The G-Luxon tested good by the way.

Yes, they tested good. How quaint. What's interesting is that whilst they were still failure prone, I noticed G-Luxon weren't quite as bad after 2000-2002ish. This is a stark contrast to Teapo which have taken a nose drive in quality over time (not that they were ever "good"), in the sense that it's a lot more common to see them blown than silently open after the early 2000s (datecode wise) than it was back in the day. Now, get this... Teapo went down in quality after the acquisition with G-Luxon and G-Luxon went up (although again, neither brand was ever good, still isn't good, and probably will never be good).

I believe "LOW ESR" is false advertising at this point in time

Or at least a hyperbole of sorts. They were probably on the "higher end" of "Low ESR" (IE general purpose low impedance, if that makes sense) when they were new. Now, of course, they are half blown to hell.

[Stefan Payne]

Re: Top Selected Power TOP-350XP

Gotta 'love' Topower...
Don't understand why anyone would ever use them (again)...

On the plus side, it has humongeous heatsinks and a chip for +5VSB.

[Pentium4]

Re: Top Selected Power TOP-350XP

Gotta 'love' Topower...
Don't understand why anyone would ever use them (again)...

On the plus side, it has humongeous heatsinks and a chip for +5VSB.

Because it's a good, silent unit. Just because you wouldn't use it, doesn't mean no one should Plus, it's green to fix something that is broken and put it to use. I think these units are pretty neat and fun to fix up.