The capacitors in the PSU?

I'm not going to be like the authors of such posts (something recently on habré became fashionable to write about how to resolder the capacitor) and not going to write a topic about how I perepaev a couple of capacitors and sapav a few contacts revived computer PSU.


In General, it was swollen in BP 2 x 10V capacitor 1000mkf. At hand was not the same and I soldered in their place 1000mkf x 16V and 25V x 1000mkf (so what has been soldered). Common sense dictates that nothing bad will happen and everything will work well, but the information on the Internet about this varies. I would like to ask the experienced and smart abrollsoftware what are the consequences of such a replacement?


And another question. The PSU is earned and feels good, but the output voltage a bit high (12.28 and 5.13), but stable — subsidence and fluctuations is not observed. Load — Mat. Board miniITX and hard disk. How dangerous is it for components?
October 8th 19 at 00:52
7 answers
October 8th 19 at 00:54
Solution
About stress: according to the specification tolerances of +5 and +12 V ±5%, i.e. a maximum of 5.25 and 12.6 V, you have everything in order.
Thank you very much. Short and to the point, all would be well answered. - Kayley_Legros46 commented on October 8th 19 at 00:57
October 8th 19 at 00:56
The voltage written on the capacitor shows essentially his margin of safety. Will give higher his strikes. You just increased the "margin of safety" capacitors, and nothing more. If you Google on the topic of power supply units to put capacitors with a supply voltage recommended almost everything, the only limitation here is the stock better to make reasonable, because the greater voltage capacitors, usually larger and more expensive.
About the increase in capacity is the Council correct in relation to the filters of power supplies, but not in other cases (say, if you significantly change the capacitance of the capacitor in the crossover of the speakers, you change the cutoff frequency and probably mess up the sound). In a traditional transformer power supply (not familiar with the pulse) the capacitor absorbs the ripple, there by increasing the capacity increases and the pulsation suppression, but at the start significantly increases the current of the primary charging of the capacitor.
Thanks for the detailed response. - Kayley_Legros46 commented on October 8th 19 at 00:59
October 8th 19 at 00:58
capacitors can be put with great features (16 vmesto 10, 25000 UF instead of 10,000 UF etc.), but not Vice versa. So that's all right.
Some arguments can provide? - Kayley_Legros46 commented on October 8th 19 at 01:01
Usually when designing power supplies with PWM to take into account possible ripple at the output taking into account the work load that smooth out capacity for rectifying the surges to a certain tolerance. On the Internet you can often find a calculation formula type for each ampere of load you need to put 10 UF capacitance. And then the more capacity the lower will be the drawdown (from the load) and ripple (from the PSU). But as long as it is economically viable (or installation size).
With regard to allowable working tension, it is usually put with a margin of 1.5-2 times due to the fact the accepted tolerance. If the capacitor will work on high mode, it can overheat and explode or even catch fire. - Kayley_Legros46 commented on October 8th 19 at 01:04
Thank you for the detailed response. - Kayley_Legros46 commented on October 8th 19 at 01:07
I can. Labelling by voltage is the maximum voltage at which is guaranteed not to occur breakdown of the capacitor. When smaller he can also work, and any characteristics of the scheme(except, perhaps, the service life of the capacitor) is not affected.
With regard to capacity — depends on the purpose of the capacitor. If the capacitor in an oscillatory circuit, the capacity is very important, and in this case the capacitor is just a filter that reduces ripple. In this case, the more capacity the better, but usually put just enough capacitors that the ripple within the tolerance. In addition, the capacitors of larger capacity are usually bigger and more expensive. - lyla.Legros74 commented on October 8th 19 at 01:10
And thank you again, shogunkub. - Kayley_Legros46 commented on October 8th 19 at 01:13
October 8th 19 at 01:00
Now you expose them a certain influence, which is slightly above the nominal indicators

The idea is that everything should work, but I would play safe

Captain, paralogistic.
The margin of operating voltage is not scary. Such a response was needed?:) - Kayley_Legros46 commented on October 8th 19 at 01:03
The answer below is accurate and confirmed by reference to the specification. Your answer is only arguments of the type "the idea" and a statement of fact "you subjected them to a particular effect, which is slightly higher than the nominal indicators" - Kayley_Legros46 commented on October 8th 19 at 01:06
October 8th 19 at 01:02
Each chip has a certain "margin of safety", in other words - the difference, within which all the components of the schema work fine (a simple example - the lamp "Ilyich", designed for 220-240V.). Now you expose them a certain influence, which is slightly above the nominal indicators (12.28 instead of 12 and 5.13 instead of 5, although of course that power supply is not producing exactly 5 and exactly 12V).
The basic characteristic of capacitor is the capacitance. In Your case it has not changed. The idea is that everything should work, but I'd play safe and went to a radio parts store...
I have answered below :) - Kayley_Legros46 commented on October 8th 19 at 01:05
October 8th 19 at 01:04
On the motherboard you can put electrolytic capacitors of smaller capacity. Checked. I instead put 1800 3300 mkf/ A voltage careful. The fact that the capacitor at 25 volts during discharge gives 25 volts. If you replace the capacitor on the 6.3 V in cond. 25, the possible failure of the motherboard capacitor discharge at shutdown. Well, if the protection type of the Zener diode the varicap... And if not... Definitely a failure of the motherboard.
What are you talking about?
The capacitor voltage is not cut off and does not regulate, in conder can be submitted 6.3 and 7 volts and it will skip them and work, and also to issue 7, but not for long, if you submit even more - it will boil and can vzorvalsya.
In the power supply is 16 volts, you can even conder at 400V solder, but in size it will not fit. - Kayley_Legros46 commented on October 8th 19 at 01:07
: To put out the voltage you need to choose capacity: grimmi.ru/kondensator-vmesto-resistora.html - Kayley_Legros46 commented on October 8th 19 at 01:10
As far as I know, a capacitor has a capacitance of 150 picofarads never skips an alternating voltage of 50 Hz, but passes the high frequency.
If you charge the capacitor, designed for a voltage of 250V with a voltage of 6 volts, for example, from the battery, and disconnect and then grab the ends of the capacitor, we get a discharge of 250 V.
Capacitor, discharging generates voltage equal to the difference of potentials between the plates. From Kond. 250 V. it is equal to 250 volts. - Kayley_Legros46 commented on October 8th 19 at 01:13
October 8th 19 at 01:06
The Chinese put a 16V in PSU 1000мФ conduci because they are cheaper, in fact if you put on 25V 1000мФ nothing will happen, just konyukov will be more headroom for peak voltage. For example a standard 16V 1000мФ vzbivayte or sometimes explode not only from peak voltages, but the temperatures in the PSU. I also put kondukov 25V instead of 16V and BP is still living longer than before failure.

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