Rebuilt ATX 1.3 PSU for Pentium II

[Pentium4]

So for once, I can't be made fun of for working on an old ATX 1.3 half bridge unit because it is being used in a Pentium II machine

I found this unit at the local PC recycling store for $4. It's a decent looking ATNG unit. Keep in mind, this thing had never had power applied to it! It was made in early 2009. This will give us an idea of the quality of Teapo caps compared to Japanese parts. You probably quickly noticed the bulged 2200uF 10V Teapo SC. It read 2020uF 0.72Ω ESR. Some of the other caps were out of spec as well without bulging. Such as one of the 1000uF caps on the 5VSB that read 1359uF.

What you also probably noticed is those huge resistors, especially on the 5V rail. 7.5Ω, what's up with that? 10Ω on the 3.3V rail. 270Ω on the 12V. So the first thing I did was plug in the unit with a paperclip to make sure it worked, and to see how much power it burned just to be running. Well, it was pulling 22W AC! That's the highest I've seen in any unit. That 7.5Ω resistor got really hot pretty quickly, imagine that It's making what, over 3W? If this thing had actually been put in service, I can only imagine how fast that resistor would have cooked the caps on the -12V and -5V rail, even the way the fan is mounted. The fan is placed in the front of the PSU, blowing towards the back of the unit, but the fan spins pretty slow. Since I was going to use this unit in a 5V based machine, I replaced the resistor on the 5V with a 240Ω resistor. I replaced the 10Ω resistor on the 3.3V with 24Ω. It still burns a fair amount but a lot less than the original. I left the 270Ω resistor on the 12V since it wasn't going to have much load on it at all.

I replaced all the electrolytic capacitors except for the 680uF CS caps on the input. I'm not sure if they were actually 680uF at one point, because they would have degraded since then sitting for 6 years. They read 583uF and 597uF. Interestingly, the Teapo SEK seemed to hold up better than the Teapo SC. Is this because the SEK are GP, so they don't have as good of specs to hold in the first place? The only thing that was somewhat sketchy was replacing the cap before the coil on the 12V rail. They originally had a 2200uF 16V 10x30mm Teapo SC. 1780 ripple current and 0.032Ω ESR. Since they had suspended the cap to fit in a 8mm slot, I used a 1000uF 16V 8x20mm 1560 ripple current and 0.030Ω ESR. I'm not worried so much about the RC or ESR, but the capacitance. I also figured that it wouldn't matter that much since this unit will hardly be using any 12V at all.

The bridge rectifier is 6A, and this unit surprisingly uses beefy 2SC2625 switchers.

I figured that the rectifiers were a little underspecc'd. 30A on the 5V and 20A on the 3.3V. So I put the 30A schottky from the 5V on the 3.3V, and put a 40A schottky on the 5V rail. I left the 16A ultra fast on the 12V because I know that with such a low load on the 12V, a schottky or higher rated ultra fast would have just shot up the 12V rail. It sits at a nice 12.08V in this system so I'm happy. I think it's odd how much bigger the 3.3V toroid is compared to the other one. I guess it's a true 1.3 unit

The soldering isn't bad at all, but there were some leads that definitely needed to be cut. I redid a few of the joints. The sleeve bearing Globe Fan had a really dry bearing so I oiled it.

After replacing the capacitors, rectifiers and minimum load resistors, the PSU then pulled 12W from the wall just using a paper clip to turn it on. Quite a difference!

The system it's powering is a Pentium II 300MHz, 128MB 100MHz SDRAM, 4x AGP video card, 3ware 8006-2LP RAID card running a RAID 1 with two Western Digital WD800JD. It also has an old Intel + Realtek 10/100 network cards. (That PSU pictured was a test Sun Pro PSU). I installed the hardware into an actual desktop style chassis, and put a brand new Pentium II sticker on it

You should have seen the look on the dude's face when I asked if they had any recycled Pentium II equipment. "A Pentium two?! Did I hear you right?" I got the board and proc for $7. What it's doing is it's a router/firewall/VPN at my brother's apartment so that now we can connect our networks.

[Wester547]

Re: Rebuilt ATX 1.3 PSU for Pentium II

Wait a moment... that 10mm Teapo bloated on its own!?!?

....

Teapo! At least their 105*C capacitors. I've had better experiences with their 85*C capacitors for some arcane reason but maybe that's because they're usually in low stress applications.

There's no rhyme or reason to explain why those SEKs held up better than the SCs. Teapo are just unpredictable like any other crap brand. And I would think that as the CS capacitors sat for so long that their dielectric thinned, decreasing their maximum voltage and ESR but increasing capacitance (though with the shoddy raw materials, anything could happen, such as dried up electrolyte), as that's what happened with the 8x15? 1000uF 10V Teapo SC on +5VSB judging by the high capacitance (however, that might change if you reform those capacitors that haven't bulged). I think the 2200uF 10V 10x20 Teapo SC bloated on its own because as the dielectric thinned, some imperfection arose, somewhere in the oxide film, and that caused hydrogen gas to form. Crappy raw materials IOW. It looks to me like the unit was actually manufactured in late 2008.

And I think that's a GeForce 2 or 4 MX.

[Stefan Payne]

Re: Rebuilt ATX 1.3 PSU for Pentium II

I'd say the graphics card is a GF FX 5200...
Geforce 4 MX rarely had a DVI...

And don't Electrolytic caps age faster when in storage than when used??

[Pentium4]

Re: Rebuilt ATX 1.3 PSU for Pentium II

It looks to me like the unit was actually manufactured in late 2008.

I thought so too, but there are four Teapo SC caps manufactured in January, 2009 (Including the one that bulged). The four manufactured in January, 2009 have a different colored paint than the other SC caps. The others were manufactured in August to October, 2008. And an oddball SEK manufactured in November, 2007.

Wait a moment... that 10mm Teapo bloated on its own!?!?

Is that a first?

And I would think that as the CS capacitors sat for so long that their dielectric thinned, decreasing their maximum voltage and ESR but increasing capacitance

As far as just sitting goes, does it have to do with the size of the capacitor? Because it's probably safe to say that CS is lower quality than Teapo. I didn't take a picture, but these CS caps had a very strange rubber seal, one I had never seen similar to any other. I also had a Sun Pro with 820uF 200V CS caps on the primary. The two caps were manufactured on October 2, 2006. It sat brand new in the box and didn't have power applied to it till April, 2014. They both read ~810uF. Here is the post: https://www.badcaps.net/forum/showpo...postcount=1792
Also my favorite Sun Pro

(however, that might change if you reform those capacitors that haven't bulged).

So, I had taken these pictures, then applied power via the paperclip, and let it run for about 10 minutes. Probably not long enough to reform them very much though?

I'd say the graphics card is a GF FX 5200...

Yeah, made by Asus.

And don't Electrolytic caps age faster when in storage than when used??

Probably. That's why they have a rated shelf life. And, they were designed to be used, not sit. That's my guess

[Wester547]

Re: Rebuilt ATX 1.3 PSU for Pentium II

I thought so too, but there are four Teapo SC caps manufactured in January, 2009 (Including the one that bulged). The four manufactured in January, 2009 have a different colored paint than the other SC caps. The others were manufactured in August to October, 2008. And an oddball SEK manufactured in November, 2007.

It's hard to tell from the pictures, but in that case January 2009.

Is that a first?

That I've seen yes. But since Teapo are proficient at silently failing I suppose it doesn't say much.

As far as just sitting goes, does it have to do with the size of the capacitor? Because it's probably safe to say that CS is lower quality than Teapo. I didn't take a picture, but these CS caps had a very strange rubber seal, one I had never seen similar to any other. I also had a Sun Pro with 820uF 200V CS caps on the primary. The two caps were manufactured on October 2, 2006. It sat brand new in the box and didn't have power applied to it till April, 2014. They both read ~810uF. Here is the post: https://www.badcaps.net/forum/showpo...postcount=1792
Also my favorite Sun Pro

I don't consider Teapo any better than CS. In fact, I don't consider Teapo any better than Fuhjyyu and CapXon. I used to consider them okay if they weren't abused by heat, but not anymore. They fail way too often without bloating and often bloat when you least expect it. Teapo weren't so bad until Yageo acquired them in 1996 so maybe it's just safer to say that Yageo sucks. I guess the Teapo issues aren't exclusive to the 8mm and smaller ones - they all suck (at least the 105*C ones)!

So, I had taken these pictures, then applied power via the paperclip, and let it run for about 10 minutes. Probably not long enough to reform them very much though?

If you measured them after then they're probably bad.

Yeah, made by Asus.

I noticed that the ASUS GeForce 4 MX and FX 5200 cards look almost identical.

Probably. That's why they have a rated shelf life. And, they were designed to be used, not sit. That's my guess

Well, I can understand a capacitor bulging after one applies power to it (voltage and current), if the dielectric has eroded enough and the peak current and voltage is strenuous enough it could cause them to bulge. But just bulging after sitting for so long with no voltage across its plates or without conducting any current, suggests major chemistry issues if they haven't been overheated. That's the thing I'd expect to see from KZGs and KZJs. The worst that should happen is that the rubber bung would eventually degrade over a long period of time and electrolyte would eventually leak from the bottom. Japanese capacitors from the 80s and early 90s bear great notoriety for that.

[Behemot]

Re: Rebuilt ATX 1.3 PSU for Pentium II

RV350, AP-400X from outside, AP-350X inside

[momaka]

Re: Rebuilt ATX 1.3 PSU for Pentium II

Not sure how I missed this, but nice thread and awesome repair (as usual)!

Is that a Dell motherboard with i440BX chipset, by any chance? Just wondering, because it looks awfully familiar to the motherboard in my Dell Dimension XPS R400. I am guessing that it is, because I see a CPU/case fan with a bright-green shroud, which is typical for Dell PCs. Also, I find it cool (and funny) that the motherboard (or at least mine) has 25V 2200 uF Panasonic FC caps for both the high side and low side of the CPU VRM. I started pulling those caps on my motherboard so I can use them in PSUs and I put 6.3V 2200 uF Nichicon HZs in their place (which, I am sure, that motherboard won't complain about).

Anyways. I wish I knew you were looking for an old PC like that. I could have sent you mine for free.

[Pentium4]

Re: Rebuilt ATX 1.3 PSU for Pentium II

Not sure how I missed this, but nice thread and awesome repair (as usual)!

Thanks! This definitely seemed like a project you would enjoy seeing.

Is that a Dell motherboard with i440BX chipset, by any chance? Just wondering, because it looks awfully familiar to the motherboard in my Dell Dimension XPS R400.

Same chipset, but it's actually from a Gateway machine. I forgot the model number though.

Also, I find it cool (and funny) that the motherboard (or at least mine) has 25V 2200 uF Panasonic FC caps for both the high side and low side of the CPU VRM.

Interesting. Mine uses all 2200uF 16V Panasonic FC. They all look okay, and I know that they are very old but I left them. They don't run warm at all.

Anyways. I wish I knew you were looking for an old PC like that. I could have sent you mine for free.

Shoot. Well, I appreciate the kind gesture I guess on the bright side, I saved this thing from that recycle store. I doubt anyone else would have used it, they were probably going to just throw it away.

[momaka]

Re: Rebuilt ATX 1.3 PSU for Pentium II

Thanks! This definitely seemed like a project you would enjoy seeing.

Well, now that I look at the thread date, I actually finished rebuilding an ATX 1.3 PSU around the same time as well. So yes, I definitely enjoyed reading through this thread .

Interesting. Mine uses all 2200uF 16V Panasonic FC. They all look okay, and I know that they are very old but I left them. They don't run warm at all.

I guess my memory isn't worth crap these days oh: . Just checked my board, and the Panasonic FC caps are all 16V indeed. I think I got it mixed up with an old proprietary Astec PSU of mine, which has all 2200 uF 25V Panasonic HFQ caps on all rails.

Shoot. Well, I appreciate the kind gesture

No problems
BTW, I might also have that HP Pavilion 8756C PC (like the one you said you used to have many many years ago) freed up by the end of the summer (or possibly earlier). If you have a use for it, let me know. It's got a TDA1517 amp on the audio output, so you can drive speakers directly. I haven't tried driving floor standing speakers with it, but I think it will work fine and sound good. After all, the TDA1517 is capable of up to 6 W/channel.

I guess on the bright side, I saved this thing from that recycle store. I doubt anyone else would have used it, they were probably going to just throw it away.

That's how I found my Dell XPS R400 too. It was a curb alert on Craigslist many years ago. Back then I only had 2 other computers, and they were in use, so it was a nice PC to play around with at the time.