Types of electrolytic caps

[Askic]

Hello guys,

can you explain me what type of caps is the one shown in the attached picture. Is is different from so called classical one. I have taken a photo of these caps next to each other. The data written on the cap is 22 uF, 50V, PH, 116, H1 KO H1.

On many motherboards there are different types of electrolytic caps. These look more robust (probably aluminium capacitor).

Do they have some special purpose?
I have one 22 uF, 50V so called robust cap and other "classical", the same capacity and 63V, but smaller dimensions.

[Per Hansson]

Re: Types of electrolytic caps

At first I thought your cap was very similar to this one I posted about here:
https://www.badcaps.net/forum/showthread.php?p=257252

I may be wrong though, and if so it is probably a solid polymer aluminium capacitor.
Basically they do not have any wet electrolyte and hence have much higher rated ripple current and a much longer life.
This thread has a bit explanation about it, but I am sure others can point you to better resources here on Badcaps.
https://www.badcaps.net/forum/showthread.php?t=65732

[Askic]

Re: Types of electrolytic caps

At first I thought your cap was very similar to this one I posted about here:
https://www.badcaps.net/forum/showthread.php?p=257252

I may be wrong though, and if so it is probably a solid polymer aluminium capacitor.
Basically they do not have any wet electrolyte and hence have much higher rated ripple current and a much longer life.
This thread has a bit explanation about it, but I am sure others can point you to better resources here on Badcaps.
https://www.badcaps.net/forum/showthread.php?t=65732

Thank you Per, based on your suggested keywords, I was able to find a very good explanation:
https://www.gigabyte.com/microsite/1...hyusesolid.htm
This motherboard manufacturer has so called "ultra durable" motherboards with this type of caps.

My dilemma is whether to replace solid aluminium cap with a classical one. I have an electronics card about 20 years old (PLC input card) which works most of the time but suddenly stop behaving as expected. After Power OFF/ON it works for another period of time. I was thinking to try to preventively replace the caps.

[Per Hansson]

Re: Types of electrolytic caps

In that case I think my first link above might be correct.
I.e. that a Rubycon ZL or similar would be a good replacement.

[Askic]

Re: Types of electrolytic caps

In that case I think my first link above might be correct.
I.e. that a Rubycon ZL or similar would be a good replacement.

Thank you very much Per. I know this is not related to the discussed subject, but can you tell me what exactly is the PSU's "startup cap", you put it yourself under quote marks in the following link: https://www.badcaps.net/forum/showthread.php?p=257252

[Per Hansson]

Re: Types of electrolytic caps

It is a small capacitor that is usually on the primary side of the power supply.
It controls the startup of the power supply, and if this capacitor goes bad the PSU will appear completely dead.
Not all power supplies have a startup capacitor, it is a kind of old design practice.
Usually you can identify it it is the problem by heating the power supply up:
If it starts after that it is likely to be a bad startup capacitor, see here for an example of that:
https://www.badcaps.net/forum/showth...875#post114875

[PeteS in CA]

Re: Types of electrolytic caps

Thank you very much Per. I know this is not related to the discussed subject, but can you tell me what exactly is the PSU's "startup cap", you put it yourself under quote marks in the following link: https://www.badcaps.net/forum/showthread.php?p=257252

In a 384x design it would be something like C2 in this schematic:



When AC is first turned on, C2 is charged through R2 until the voltage is high enough for IC1 to turn on. Once turned on, IC1 receives its Vcc through D2 and D1. However, if C2 is high ESR, the energy drawn by IC1 lowers the voltage at Vcc and the under-voltage protection in IC1 shuts down IC1.

In that circuit both C2 and C4 are stressed and need to be high quality parts such as Nichicon PW series or UCC/NCC LXZ series.

[Askic]

Re: Types of electrolytic caps

Excellent explanation Petes, thank you and also Per for your time and effort.