Another Macron MPT-301 saved

[Pentium4]

Yep, I definitely have a soft spot for these old Macron's. But they're very respectable units. This one, when I got it, had seen better days. Even the Power Logic ball bearing fan was getting tired. Just about every cap in this thing failed. They only consist of 12Kuang Jin and CEC International. I can't really blame the CS caps too much for failing, their date codes are all from January, 2003 and the unit saw about 55,000 hours of running time in a very hot office with an Athlon XP machine. Every filtering cap was CS, and every single one was bulged and leaking except oddly enough one (Not pictured...) The 470uF 25V one on the 5VSB auxiliary tested perfect, 472uF 0.02Ω ESR. All the CEC caps tested good, but they only ranged from 1-22uF 50V. I replaced them all anyways.

Another strange thing, the two input caps were CS 680uF 200V. They both looked like they were bulging underneath the plastic discs over the top. Sure enough, they were. However....they tested perfectly in spec. ~720uF 0.13Ω ESR. Do you think they were tricking my meter? I ended up replacing them anyways. I upgraded the 12V rectifier from the stock 16A ultra fast to that 30A schottky. 12V runs very strong. It could handle a Pentium 4 3.6GHz and 9600GT under full load all day long and stay at a firm 12.16V compared to 11.83V before with the same load. I also noticed that the snubber resistor on the primary was cooking the film cap for the switchers. Since I have so many lying around, I replaced the 1uF stock one with a 2.2uF part. I also removed the primary heatsink to tighten the screws.

I also moved around or replaced the minimum load resistors on the 5V and 3.3V. 12V didn't have one, so didn't have to worry about that. The ones on the 5V and 3.3V were way too low. I can't remember exactly but I think the new ones I put on the 5V and 3.3V were 100Ω. One of the stock ones was 22Ω and the other 47Ω

Also replaced the stock fan with that oiled sleeve bearing fan and added a SATA power cable. It's very silent even under heavy load. The thing looks great now!

[Wester547]

Re: Another Macron MPT-301 saved

~720uF 0.13Ω ESR. Do you think they were tricking my meter?

Depends on how fast they responded to the meter (IE if the ESR values were rapidly falling or if they were slow to respond to the meter and to reach the specified value). It really does seem like it's a hit or miss with these "bad" brands. Sometimes they last many years of use before failing like in this instance and sometimes they don't last a year.

[goodpsusearch]

Re: Another Macron MPT-301 saved

Another strange thing, the two input caps were CS 680uF 200V. They both looked like they were bulging underneath the plastic discs over the top. Sure enough, they were. However....they tested perfectly in spec. ~720uF 0.13Ω ESR. Do you think they were tricking my meter? I ended up replacing them anyways.

Oh, man you reminded me my first thread and post in that forum!!

https://www.badcaps.net/forum/showthread.php?t=8125

Unfortunately I didn't own the equipment back then to test the bulging caps, so I replaced them anyway. Later, when I bought my esr micro meter and tested them, they were found perfectly ok in terms of esr and capacity, like yours.


Excellent work as always

[Pentium4]

Re: Another Macron MPT-301 saved

Depends on how fast they responded to the meter (IE if the ESR values were rapidly falling or if they were slow to respond to the meter and to reach the specified value). It really does seem like it's a hit or miss with these "bad" brands. Sometimes they last many years of use before failing like in this instance and sometimes they don't last a year.

Is it possible that the building it was being used in had a "less than good" AC line? Or is it more likely to just be the quality of caps? Cause I've never really seen high voltage caps like these fail. All the ones I've had bulge still tested good (These CS, Panasonic from an Antec SP, and Teapo from a Hipro)

Oh, man you reminded me my first thread and post in that forum!!

https://www.badcaps.net/forum/showthread.php?t=8125

Unfortunately I didn't own the equipment back then to test the bulging caps, so I replaced them anyway. Later, when I bought my esr micro meter and tested them, they were found perfectly ok in terms of esr and capacity, like yours.

Wow! Your first post, cool. Interesting that your bulged input caps acted the same.

Excellent work as always

Thanks

[Wester547]

Re: Another Macron MPT-301 saved

Is it possible that the building it was being used in had a "less than good" AC line? Or is it more likely to just be the quality of caps? Cause I've never really seen high voltage caps like these fail. All the ones I've had bulge still tested good (These CS, Panasonic from an Antec SP, and Teapo from a Hipro)

Whoops, missed the part about the fact that they were bulging.

Are the capacitors actually bulging or is the plastic cap/disc just "bloated" a bit (can you push it back down)? There also exists such a thing as a "recoverable" bulge - pressure is created inside the can but hydrogen gas doesn't form which means you can push the vent back down. In any case, if the capacitors bulged and the vents are hard as a rock, that can never be a good thing. If the capacitors were in spec then, they won't be for much longer.

As for high voltage capacitors bulging...

Electrolytic capacitors from bad brands or just bad series don't need to have any current passing through them or any voltage applied to them to fail. Capacitors aren't inactive or "off" in the way one might assume when they're in storage. They have a shelf life, even the good ones, for a myriad of reasons. The issues with bad capacitors, however, are exactly that - heat is only an acceleration of the breakdown of faulty formulas and bad aluminum foils as well as bad bungs. Without the proper additives and constituents in the electrolyte necessary to deal with any excessive hydrogen (especially in water-base electrolyte where the dielectric is at risk), capacitors can actually bulge in a sealed bag whilst still retaining their full leads (without having been ever placed into a circuit). It only takes time for this to happen and nothing else.

This is how failed Fuhjyyu primary capacitors are possible, and this is why KZGs and KZJs fail on the shelf (or really, any defective capacitor, even bad batches from good series and brands).

Bulged primary Teapos from a Hipro? Any chance that refers to the bulged 470uF 200V Teapo LHs you found in that Hipro you posted three years ago (the one with 12A @ 12V on the label and 36,000 hours on it, as well as bloated Teapo SC on the output)? Bulging Panasonic primaries? They must have run unbelievably hot in that SP to have bulged.

[Pentium4]

Re: Another Macron MPT-301 saved

Are the capacitors actually bulging or is the plastic cap/disc just "bloated" a bit (can you push it back down)?

I cut out the plastic pieces and you can see the actual capacitor bulging. However, it's very slight. But they're both definitely bulging about the same amount.

As for high voltage capacitors bulging...

Electrolytic capacitors from bad brands or just bad series don't need to have any current passing through them or any voltage applied to them to fail. Capacitors aren't inactive or "off" in the way one might assume when they're in storage. They have a shelf life, even the good ones, for a myriad of reasons. The issues with bad capacitors, however, are exactly that - heat is only an acceleration of the breakdown of faulty formulas and bad aluminum foils as well as bad bungs. Without the proper additives and constituents in the electrolyte necessary to deal with any excessive hydrogen (especially in water-base electrolyte where the dielectric is at risk), capacitors can actually bulge in a sealed bag whilst still retaining their full leads (without having been ever placed into a circuit). It only takes time for this to happen and nothing else.

Makes sense, especially for the low quality brands. But, is another reason the high voltage capacitors last so long is because they have a large amount of voltage going through them, which is good for the oxide layer? So, does this mean that these caps would last longer running, compared to not running?

Bulged primary Teapos from a Hipro? Any chance that refers to the bulged 470uF 200V Teapo LHs you found in that Hipro you posted three years ago (the one with 12A @ 12V on the label and 36,000 hours on it, as well as bloated Teapo SC on the output)?

You're exactly right Those are the ones I was referring to. They too were bulged once I pulled out the plastic pieces, but they too, tested in spec on my meter.

Bulging Panasonic primaries? They must have run unbelievably hot in that SP to have bulged.

Yes, we know how hot those damn things run. Plus, this one had about 59,000 hours on the thing. The only reason I think it lasted so long was because it ran 24/7 and was on a UPS, so the thing was literally never off for a little over 6 years. The poor, poor hard drive failed and is why it came in. Every cap in that thing failed, even all the little ones. The 1200uF Panasonic primaries were bulged but tested good. ~1075uF on both of them and ~0.16Ω ESR

[Wester547]

Re: Another Macron MPT-301 saved

Makes sense, especially for the low quality brands. But, is another reason the high voltage capacitors last so long is because they have a large amount of voltage going through them, which is good for the oxide layer? So, does this mean that these caps would last longer running, compared to not running?

Well, APFC primaries would have a higher voltage across their plates, but they seem more inclined to fail (at least for the junk brands), being under more stress than lytics in the voltage doubler, so I think there's more to it than that. I think it has to do with an individual composition of each capacitor. The dielectric does thin as long as the capacitor sits on the shelf (causing ESR to decrease, capacitance to increase, and lowering the maximum voltage until they're reformed again) but any given capacitor should not bulge because of it without ever being used. That heavily denotes chemistry issues. A capacitor should only fail if it sat for too long, is "used" again, and the peak current and voltage going through it essentially destroys it because the aluminum oxide layer is all but gone (has dissolved into the solution).

Keeping the oxide layer thick is great, but it requires more "consumption" of the electrolyte in order to "correct" weak spots in the dielectric so it's not always a good thing (the capacitor would be working closer to its maximum voltage). It's good in the sense that it stabilizes the oxide layer beyond what the inhibitors can do and keeps it more resistant to the aggressive nature of aqueous electrolyte but it only prolongs the inevitable for bad brands and bad series, in that sense.

You're exactly right Those are the ones I was referring to. They too were bulged once I pulled out the plastic pieces, but they too, tested in spec on my meter.

As I remember, you also found a 100uF 400V Taicon primary bulged in a 24 port gigabit switch. I kind of doubt that one was still in spec, though. I've had better luck with Teapo LXK than LH. I can only remember seeing failed Teapo LXK in PSUs whose fans have long seized or in PSUs where a stupid valley-fill circuit is used and creates so much heat that even Panasonic primaries would blow. On the other hand, Teapo SEK and SCs are a common sight for those who deal with failed capacitors, and they are both notorious for going open without any signs, just like OST capacitors.

Yes, we know how hot those damn things run. Plus, this one had about 59,000 hours on the thing. The only reason I think it lasted so long was because it ran 24/7 and was on a UPS, so the thing was literally never off for a little over 6 years. The poor, poor hard drive failed and is why it came in. Every cap in that thing failed, even all the little ones. The 1200uF Panasonic primaries were bulged but tested good. ~1075uF on both of them and ~0.16Ω ESR

It's natural for the little ones to dry up and increase in ESR over time (and decrease in capacitance). They aren't low ESR lytics to begin with. I think those bulged capacitors would be a bit more out of spec if you applied 120V to them.

[goodpsusearch]

Re: Another Macron MPT-301 saved

Wow! Your first post, cool. Interesting that your bulged input caps acted the same.

Yeap. The fan hasn't seized and there were no signs of overheat. The psu is not active PFC as we know. And we have 2 identical psus with the same brand of primary caps showing the same failure pattern (slight bulging). I think this can be attributed to the caps being crap.

I don't have the ones I pulled out of the Macron that was the reason I became a member here. I advise you to put the bulging caps in a crap 200W/250W psu just to see what happens.

Worst primary caps ever?
https://www.badcaps.net/forum/showth...20B#post454467

[momaka]

Re: Another Macron MPT-301 saved

Man, you are the God of Macrons
Nice save, yet again.

Yep, I definitely have a soft spot for these old Macron's.

haha, same here. I'd say probably these Macrons are second favorite to the 250W HiPro "tank" PSUs.

Another strange thing, the two input caps were CS 680uF 200V. They both looked like they were bulging underneath the plastic discs over the top. Sure enough, they were. However....they tested perfectly in spec. ~720uF 0.13Ω ESR. Do you think they were tricking my meter? I ended up replacing them anyways.

I've seen this as well - it was the 1000 uF 200V JEE primary caps in an old Leadman LP-6100D of mine. Actually, only one of the caps bulged, but both tested in spec (well, in spec for 820 uF caps - IMO, JEE forged the capacitance rating).

Best way to test such caps: charge to 15-20V and discharge with a piece of wire. If you get visible sparks, it is probably okay. And if you charge those primary caps with 50+ volts, you should get a serious pop and sparks.

I upgraded the 12V rectifier from the stock 16A ultra fast to that 30A schottky. 12V runs very strong. It could handle a Pentium 4 3.6GHz and 9600GT under full load all day long and stay at a firm 12.16V compared to 11.83V before with the same load.

Yeah, my MPT-301 also runs much better on the 12V rail now with a 20A schottky vs. 16A fast rectifier before. But with a 5V-based PC (like Athlon XP), the 12V rail jumps to 12.6V. Before, it stayed at no more than 12.25V. So I guess, if you are going to use this PSU on a 5V-based system, keep the fast rectifier. But for a 12V-based system, definitely replace it like you did.

I also noticed that the snubber resistor on the primary was cooking the film cap for the switchers. Since I have so many lying around, I replaced the 1uF stock one with a 2.2uF part.

Interesting find. I wonder if the ceramic cap in the snubber network is going bad then. Maybe pull it out and check its capacitance?

I also removed the primary heatsink to tighten the screws.

Nice touch .
I usually try to do that without removing the heatsinks. If the screw heads are not very flat, I use needle-nose pliers.

I also moved around or replaced the minimum load resistors on the 5V and 3.3V. 12V didn't have one, so didn't have to worry about that. The ones on the 5V and 3.3V were way too low. I can't remember exactly but I think the new ones I put on the 5V and 3.3V were 100Ω. One of the stock ones was 22Ω and the other 47Ω

Yes, same on mine. I think it was 25 Ohms for the 5V rail and 10 Ohms for the 3.3V rail. I don't have my files on this PC to check right now, though.
Just a word of caution: the PSU may start producing some nasty whining noises now on 12V-based motherboards with very low-power chipsets. Use the chipset heatsink size as an indicator - if it's tiny glue on stuff, it probably is very low power and your Macron may whine. Not that I noticed any problems with that, though.

Also replaced the stock fan with that oiled sleeve bearing fan and added a SATA power cable. It's very silent even under heavy load. The thing looks great now!

Ready for modern PCs now

Are the capacitors actually bulging or is the plastic cap/disc just "bloated" a bit (can you push it back down)? There also exists such a thing as a "recoverable" bulge - pressure is created inside the can but hydrogen gas doesn't form which means you can push the vent back down.

I've seen this happen many times with caps that get overheated - particularly on Xbox 360's during reflow. As long as the caps were not grossly overheated to bust open from bulging, you can push the tops back down without any problem. I've done that many times and used those bulged caps for repairs on my own equipment. Never had a problem, and some of these repairs are more than a few years old now.

But like you said, if the cap is bulged and the vent is hard as a rock - that indicates hydrogen gas pressure is present underneath. In some cases, if the bung seal is good and neither the pressure nor the electrolyte escapes, the cap may continue to hold most of its specs. I have one general purpose 85C Panasonic cap like that. It ended up bulging because I accidentally put it in reverse on a breadboard project.

[Pentium4]

Re: Another Macron MPT-301 saved

Man, you are the God of Macrons
Nice save, yet again.

Hahaha, thank you sir

Yeah, my MPT-301 also runs much better on the 12V rail now with a 20A schottky vs. 16A fast rectifier before. But with a 5V-based PC (like Athlon XP), the 12V rail jumps to 12.6V. Before, it stayed at no more than 12.25V. So I guess, if you are going to use this PSU on a 5V-based system, keep the fast rectifier. But for a 12V-based system, definitely replace it like you did.

Makes sense that it would jump so high, since they anticipated these units to be used in 5V based systems. The only 5V based system I have running anymore is a Pentium 3 system and it uses a nice Hipro. This unit actually: https://www.badcaps.net/forum/showpo...postcount=1834

Interesting find. I wonder if the ceramic cap in the snubber network is going bad then. Maybe pull it out and check its capacitance?

I'm lazily going to respond with "I think it will be fine" haha...I think it's because this unit ran in a hot office and was INSANELY dusty. I don't say that lightly either. I never mentioned before that I swapped the chassis on this thing because it was so nasty. It took a long time of using an 80 PSI hose to clean all the dust out of the unit itself. So, this Macron is being housed in a Thermal Master chassis

Nice touch .
I usually try to do that without removing the heatsinks. If the screw heads are not very flat, I use needle-nose pliers.

I do too but I almost always redo the soldering on all main silicon components, so I figured why not remove it

Yes, same on mine. I think it was 25 Ohms for the 5V rail and 10 Ohms for the 3.3V rail. I don't have my files on this PC to check right now, though.
Just a word of caution: the PSU may start producing some nasty whining noises now on 12V-based motherboards with very low-power chipsets. Use the chipset heatsink size as an indicator - if it's tiny glue on stuff, it probably is very low power and your Macron may whine. Not that I noticed any problems with that, though.

It's a shame. It doesn't just cook the caps, but reduces the efficiency too. Wow, crazy that you mention it. The unit did indeed emit a high pitched whine at any load while powering the Pentium 4 rig. It uses a 945G chipset. Not sure if the 945G is very low power though. I figured it wasn't oscillating though, since c_hegge has recapped a Macron with similar caps and the ripple was all well in spec. It's not a loud whine, but you can hear it when you put your ear up to the exhaust fan on the PSU.


So, what is it with these half bridge Macron units? They look almost identical at first glance to other old half bridge units, but perform so much better. The one c_hegge tested did 350W in spec, with the old stock crappy caps. It had really good efficiency for an old half bridge, even with the stock 16A ultra fast....AND it did 19A on that 16A part! The heatsinks aren't particularly big either. I guess I'm just impressed by these things. They must be much better with the improved rectifier on the 12V.

[goodpsusearch]

Re: Another Macron MPT-301 saved

So, what is it with these half bridge Macron units? They look almost identical at first glance to other old half bridge units, but perform so much better. The one c_hegge tested did 350W in spec, with the old stock crappy caps. It had really good efficiency for an old half bridge, even with the stock 16A ultra fast....AND it did 19A on that 16A part! The heatsinks aren't particularly big either. I guess I'm just impressed by these things. They must be much better with the improved rectifier on the 12V.

And they keep ripple low while 5V and 12V output filter don't have a coil

[momaka]

Re: Another Macron MPT-301 saved

I'm lazily going to respond with "I think it will be fine" haha...I think it's because this unit ran in a hot office and was INSANELY dusty.

That could definitely be it too. I can't argue with you, because thats how I often think myself .

So, this Macron is being housed in a Thermal Master chassis

Noooo.
A Macron without that "AMD INTEL ATX12V TEST PASS" and the goofy Macron text label just doesn't look right IMO
Hopefully no one looks at the label of this PSU now and chucks it just because it appears to be a crappy Thermal Master PSU.

It's a shame. It doesn't just cook the caps, but reduces the efficiency too. Wow, crazy that you mention it. The unit did indeed emit a high pitched whine at any load while powering the Pentium 4 rig. It uses a 945G chipset. Not sure if the 945G is very low power though.

Well, it also depends if the motherboard feeds the chipset from 3.3V rail or 5V rail. According to datasheet, Intel 945GT chipset has 15W TDP (so thats about medium power). Try putting some load on the 5V and 3.3V rails and see what happens. I will admit that this is more of a curiosity for me. My Macron was stable too, even when it was whining, so I doubt it's a problem.

Also, I'm thinking it might be the 5VSB too, then. I know on my MPT-301 it is quite loud. I tried it with various resistive loads and computers, but it is always there. It has been working fine for a very long time, though, so I thought exactly the same way as you - "I think it will be fine"

AND it did 19A on that 16A part! The heatsinks aren't particularly big either. I guess I'm just impressed by these things.

Same here. Actually, when I got my Macron a while back (maybe 2008-ish or so) and first opened it, I though, "no way this will do the 300W rated on the label with these heatsinks." But after fixing it and seeing how cool it ran both with 5V and 12V-based PCs, I changed my mind completely.