Annoying heavy load-failure in Tecnoware Free Silent 500W

[TELVM]

Re: Annoying heavy load-failure in Tecnoware Free Silent 500W

2x2200uF or maybe 2x3300uF is the maximum you can put.

Why is that? Where does that arbitrary limit come from?

Be Quiet L8 500W with at least 13200uF (6x 2200uF) on +12V rail:

=> http://www.techpowerup.com/reviews/b...L8_500W/4.html

[goodpsusearch]

Re: Annoying heavy load-failure in Tecnoware Free Silent 500W

Why is that? Where does that arbitrary limit come from?

Be Quiet L8 500W with at least 13200uF (6x 2200uF) on +12V rail:

=> http://www.techpowerup.com/reviews/b...L8_500W/4.html

We are not talking about high end power supplies here. We are talking about old half bridge or 1 transistor forward cheap ass platforms.

[TELVM]

Re: Annoying heavy load-failure in Tecnoware Free Silent 500W

L8 500 is high end?

[goodpsusearch]

Re: Annoying heavy load-failure in Tecnoware Free Silent 500W

Dude you need to focus. The psu in the link has nothing in common with those gutless wonders we are talking about here. In those psus you are lucky if they have coils installed between the caps or even space on PCB for them.

Their output caps per rail are 2x1000uF or even 2x470uF on some occasions. Putting there more than 2x3300uF is just

As a general rule of thumb, you should replace caps with same capacitance or 1 to 2 sizes bigger.

[TELVM]

Re: Annoying heavy load-failure in Tecnoware Free Silent 500W

... Putting there more than 2x3300uF is just ...

Why? What would happen if i put 2x 4700uF?

Just want to know the reasoning behind the rule of thumb.

[goodpsusearch]

Re: Annoying heavy load-failure in Tecnoware Free Silent 500W

First, the esr drops too much. The same reason you should not recap psus with mobo grade caps.

It also has to do with the feedback circuit.

If the total output capacitance of a rail exceeds what the psu manufacturer had in mind when he designed the feedback circuit, then you get oscillations.

For example this psu has issues when it is connected with 12V power hungry PCs:
https://www.badcaps.net/forum/showthread.php?t=23996

The situation gets worse if you try to replace the 12V output caps with ones of bigger C.

[momaka]

Re: Annoying heavy load-failure in Tecnoware Free Silent 500W

Yeah and now take unknown unit and try to measure power output through the wattmeter. You'd be glad to get 10% error.

I've already done that with a few random SMPSes of mine, including some ATX PSUs, and got reasonable results as I did above. Anyways, we've already had a thread on this stuff, so I won't get into this discussion here.

Their output caps per rail are 2x1000uF or even 2x470uF on some occasions. Putting there more than 2x3300uF is just

Not really.

In SMPS, high capacitance is *always* more favorable than anything else, especially for older designs (half bridge and STF) where the switching frequency is relatively low. (Think about an audio amplifier with a line transformer - those always have huge caps, and that's because at 50/60 Hz, they really are needed to produce a smooth output voltage. And that's the whole idea behind SMPS: increase the transformer switching frequency so that you have have a smaller transformer and smaller output caps. The further you increase the frequency, the further you can shrink down components.) In general, there isn't really any limit to how high you can go with the capacitance. However, keep in mind that the inrush currents will also be larger with larger output caps, so the rectifiers and coils will be stressed more during power-ON sequence. And if the PSU lacks soft-start, then you may even burn a rectifier out. But other than that, the feedback loop will almost always be much happier with the higher capacitance.

Speaking of the feedback loop, the capacitor ESR comes at a distant second. And by that, I mean you don't want to go too high, but definitely not too low either. Keeping it close to original is the best thing to do. (Too high of an ESR means that noise and ripple won't get filtered too well. Conversely, too low of an ESR means that noise and ripple will be filtered very well, but the low ESR of the caps may cause ringing, which is essentially noise and ripple generated from the output filters themselves.) However, if you increase the capacitance, then a decrease in the ESR may not be as critical.

Also, again, this will depend on the SMPS design. Higher frequency designs may be able to cope better with smaller capacity and lower ESR caps. But for an older design, like the cheap PSUs in this thread, higher capacitance will be a lot more important than keeping the ESR low. So for example, if you had to choose between 2x 2200 uF low ESR caps (such as Nichicon HE or Chemicon KY) and 2x 4700 uF general purpose 105C caps, go with the 2x 4700 uF caps. Most manufacturers simply don't do this because with the above example, the 4700 uF general purpose caps will be much larger than the 2200 uF low ESR ones, which means more space is needed on the output side of the PSU (which may not be an option). And in many cases, the 2x 2200 uF caps may actually turn out to be cheaper, despite being low ESR.

As a general rule of thumb, you should replace caps with same capacitance or 1 to 2 sizes bigger.

Not if it's a cheap low quality PSU - for those, you disregard what's in the PSU and simply go by the rule of thumb I listed in post #16.

For example this psu has issues when it is connected with 12V power hungry PCs:
https://www.badcaps.net/forum/showthread.php?t=23996

The situation gets worse if you try to replace the 12V output caps with ones of bigger C.

That's an older Sirtec design. They often seem to have issues with 12V power-hungry systems, especially if you increase the capacitance on the 12V rail (and then even worse if you use low ESR caps). But those are the only PSU's I've seen that do this. Go figure

[TELVM]

Re: Annoying heavy load-failure in Tecnoware Free Silent 500W

It is known that the cheaper the PSU, the smaller the output caps, and viceversa. So one is tempted to suspect that deployed capacitance may be more related to budgetary than to electrical reasons, and that larger capacitance may in fact be a good thing.

About rules of thumb, Seasonic might have their own private ones. Look at this humongous 4700uF KZE (ESR=15) they put on +5VSB inside the Antec Truepower New 650W:



Together with its 1000uF companion downstream of the PI coil that amounts to 5700uF for +5VSB only.


BTW I've noticed that when they do that (one bigger and another smaller cap on +5VSB) the bigger one is often placed the closest to the +5VSB transformer, is there any particular reason for that?

[momaka]

Re: Annoying heavy load-failure in Tecnoware Free Silent 500W

BTW I've noticed that when they do that (one bigger and another smaller cap on +5VSB) the bigger one is often placed the closest to the +5VSB transformer, is there any particular reason for that?

Yes.
Long traces = good antennas. Square waves traveling on the output will produce EMI and possibly some RFI as well. Placing the cap as close as possible to the transformer output makes the PSU produce less EMI/RFI, since the noise and ripple on the output is shunted to ground quicker without going through long traces. This also reduces noise on the output that comes from external EMI and RFI.

[omega]

Re: Annoying heavy load-failure in Tecnoware Free Silent 500W

Back to the main subject of this thread, now that I 've recapped nine PSUs FAL501FS12 I have some statistics of the voltages (most ATX are already under stress, I will let you know about the results). Most of the recapped follow the voltage schema depicted in post #56, however two PSU get following similar voltages:
nominal before recap, 21W after, 21W after, no load
12 V 12.4 V 12.7 V 12.9 V
5 V 5.5 V 5.4 V 5.4 V
5 VSB 5.1 V 5.1 V 5.1 V
3.3 V 3.4 V 3.3 V 3.4 V
–12 V –11.9 V –12.0 V –12.0 V
PG 5.4 V 5.3 V 5.3 V
I think the voltages are high with respect the average, am I wrong? any clue how comes and how to fix?

[RJARRRPCGP]

Re: Annoying heavy load-failure in Tecnoware Free Silent 500W

Also, the "500W" rating is absolutely fake! At most, this power supply will give you 200 Watts raw power.

QFT! And if you OC a Q6600 to 3.3 with 1.4V of Vcore, the CPU alone will use 250W easily!

[TELVM]

Re: Annoying heavy load-failure in Tecnoware Free Silent 500W

^ Nope you're misinformed RJARRRPCGP, it'll only draw ~135W @ 3.9 GHz. See here.


Even an i7-950 @ 4.2 GHz is ~50W short of drawing 250W:

[RJARRRPCGP]

Re: Annoying heavy load-failure in Tecnoware Free Silent 500W

^ Nope you're misinformed RJARRRPCGP, it'll only draw ~135W @ 3.9 GHz. See here.


Even an i7-950 @ 4.2 GHz is ~50W short of drawing 250W:

That's a 45 nm Core 2 on the right, which uses a lot less power.

I'm talking about a 65 nm Core 2 Quad. Way before i-series!

http://www.anandtech.com/show/2303/4

Mine required more Vcore than theirs for 3.3...

[momaka]

Re: Annoying heavy load-failure in Tecnoware Free Silent 500W

Most of the recapped follow the voltage schema depicted in post #56, however two PSU get following similar voltages:
nominal before recap, 21W after, 21W after, no load
12 V 12.4 V 12.7 V 12.9 V
5 V 5.5 V 5.4 V 5.4 V
5 VSB 5.1 V 5.1 V 5.1 V
3.3 V 3.4 V 3.3 V 3.4 V
–12 V –11.9 V –12.0 V –12.0 V
PG 5.4 V 5.3 V 5.3 V
I think the voltages are high with respect the average, am I wrong? any clue how comes and how to fix?

Yes, they are quite high (the 12V and 5V rails, that is). In fact both are out of spec on the last two columns. Speaking of which, what do you mean by, "nominal before recap, 21W after, 21W after, no load"?

I think you *may* be able to fix that, if you're talking about the Technoware PSU revision in post #14. That one uses an SDC2921 PWM controller. This is its datasheet:
https://cdn.badcaps-static.com/pdfs/...1d9ec648b2.pdf

According to the typical application on page 9, it appears that pin 16 (VIN+) sets the voltage output through variable resistor "R2". With some tracing on your PSU, I believe the resistors circled in red in the picture below is what sets the output voltage.
https://www.badcaps.net/forum/attach...1&d=1454552789
All 3 of them appear to be in parallel, and that is what makes up "R2" on the SDC2921 datasheet. Can you please post the resistance values of each resistor? You will need to remove them out of the PSU if you want to measure them.

[TELVM]

Re: Annoying heavy load-failure in Tecnoware Free Silent 500W

... I'm talking about a 65 nm Core 2 Quad. Way before i-series!

http://www.anandtech.com/show/2303/4

Notice it's total system draw in the Anandtech graphs, not CPU draw alone.

65nm Kentsfield Q6600 are 95~105W TDP. 45nm Yorkfield Q9505 are about the same, 95W TDP.

[RJARRRPCGP]

Re: Annoying heavy load-failure in Tecnoware Free Silent 500W

Notice it's total system draw in the Anandtech graphs, not CPU draw alone.

65nm Kentsfield Q6600 are 95~105W TDP. 45nm Yorkfield Q9505 are about the same, 95W TDP.

I believe the motherboard and the GPU only add a tad more, unless doing 3D rendering with the GPU...

It does seem to be exponentially higher, if not exactly that and without exaggeration , it's easily about 230W alone, IIRC, when I saw one for x264, which was a CPU-only test...

3.0 OTOH seems to use exponentially less and that's why I use that for the system with my Halo CE server...

I think the 45 nm version is easier on the system...

[omega]

Re: Annoying heavy load-failure in Tecnoware Free Silent 500W

Momaka, thanks you so much for the steady support!

Speaking of which, what do you mean by, "nominal before recap, 21W after, 21W after, no load"?

sorry a comma has been dropped out!
nominal is the value which has been printed n PCB
before (after) recap is before (after) the cure, with 21W load (or no load).
It's a pity that I cannot attach a Table

I think you *may* be able to fix that, if you're talking about the Technoware PSU revision in post #14.

Yes, they all are FAL501FS2

With some tracing on your PSU, I believe the resistors circled in red in the picture below is what sets the output voltage.

I can also see that a place on the left of the red square you sketched is EMPTY. If I am remember, it is NOT missing, but this pic has been taken from one of the two PSUs with high voltage. I will check it soon. Anyway they appear to be 1% precision (namely hard-to-find) resistors.

[Behemot]

Re: Annoying heavy load-failure in Tecnoware Free Silent 500W

I've already done that with a few random SMPSes of mine, including some ATX PSUs, and got reasonable results as I did above. Anyways, we've already had a thread on this stuff, so I won't get into this discussion here.

I have a strange feeling you are talking about something completelly different.

I am talking about measuring output power with meter on input. That is guessing at best as you have no idea what's the efficiency of that thing. Compared to that, even cheap clamp meter with like +-3 % accuracy is still much more precise.

What the wall meter actually shows is even another, completelly different thing (which also affects the result, however).

[momaka]

Re: Annoying heavy load-failure in Tecnoware Free Silent 500W

I can also see that a place on the left of the red square you sketched is EMPTY. If I am remember, it is NOT missing, but this pic has been taken from one of the two PSUs with high voltage. I will check it soon. Anyway they appear to be 1% precision (namely hard-to-find) resistors.

Yeah, I noticed that as well. Looks like there was a resistor (R12?) in there originally and it was cut off at the factory perhaps? Looks like it's part of the compensation network, but I don't know what exactly it does or what to put in there.

One easy thing you can do, however, is take one of the PSUs that you fixed that has normal voltages and compare the resistors it has to the PSUs that have the abnormal high voltage condition. Let me know what you find out.

Also, don't worry that the resistors are 1% precision. You could use 5% too if the 5% resistor happens to measure within 1% accuracy. The manufacturer only used 1% so that they don't have to take time tweaking the PSU outputs if the outputs weren't exactly spot-on right.

I am talking about measuring output power with meter on input. That is guessing at best as you have no idea what's the efficiency of that thing.

You're right, I am guessing indeed . But for an old half-bridge design, you can assume the efficiency to be around 70% +/-5% most of the time and your results won't be too far off. If anything, you should get a pretty decent *estimate* of the power consumption - usually within 10% of what it is. I know that is not precise at all, but it does give you an idea more or less how much power your PC is using.

[omega]

Re: Annoying heavy load-failure in Tecnoware Free Silent 500W

This to post bad and good news together
So far I recapped nine Technoware FAL501FS12 (just the secondary section), with replacement of the 12V rail diode as momaka suggested me, and had also time to test them "in the field" under stress load (100% CPU 24/7), as usual in my field of research.
The bad news is that some work, some not (namely I get the infamous ATAPI error 9 and 11). After checking the soldering of every "bad" PSU, have been trying for hours to give myself an explanation through a correlation and today I think I succeeded in finding it (that's the good news): at present the PSUs which have worked bad after fixing all have rail voltages, as measured by the program SpeedFan (v 4.51), which exceed 5% the nominal 12V, i.e. > 12.6V (+/-5% the nominal is it the specification you meant, right?). I think that may be due to the resistor R12 (470k) missing in some of the recapped PSUs (it has been factory cut, there are still soldered rheophores), probably to increase the then low 12V rail. Indeed, the recapping and replacement of the fast recovery diode with a Schottky one, have increased the voltage of about 200-300 mV, maybe going beyond tolerance. Since I got at home a tenth PSU to recapped and in this R12 is missing too, I measured 12V rail (under 21W load) before and after putting a 470k (still no recap) and found a lowering of 600 mV. Good!
Next week I will check at work if the correlation between ATAPI error and the lacking of R12 holds and fix the PSUs accordingly.
The bottom line: electronics repair may be either frustrating or funny, however all is best after one finds good teachers. Thanks to the group members and in particular to Momaka!