Understand caps a little bit more! Short on PPBUSG3H

[Maxibon]

Hey guys! I’m wondering if anyone can help me with a knowledge gap I have that can either point me in the right direction or explain the following to me!

The device: A1706 820-00236
The issue: short to ground on PPBUSG3H
What caused the short: failed cap. Cap specs: 33uf 16v 20%
My questions I can only get my hands on 47uf caps in 10 packs from mobile sentrix. Is this the case, because one size fits all?

I’m a little lost why I can find multiple different spec and sizes caps for sale in bulk. Is harvesting a cap from the same spot on the same model device, same spec the only way to ensure you’re using 100% the right one. On that same PPBUS line there is a cap that is 2.2uf 25v 20% totally different physical size as well. So far anytime I have a short on VCC main or PPBUS etc I just leave the caps off. I’ve been doing this for years and have no issues with this though I want to understand why.

Thanks in advance!

Max

 

[2informaticos]

The ESR factor is very important factor of the big caps.
They are used as energy reservoir and must allow high current discharge.
You can pick them from older scrap boards.
Sometime you can put bigger size, scratching the copper pads.

Tollerance is not important at all, just be sure to choose same, or bit higher nominal voltage.
Depending where the cap is placed, you can use the same capacity, or higher (not too much).

Many times will not solder back small capacity caps, but must understand if is really needed, or not.
1-22uF seem to be not high capacity, but when these are placed near the drain of an High-Side MOSFET from a secondary supply, these caps are CRITICAL!

Do NOT buy book kits with ceramic caps, or resistors + caps from eBay, or Aliexpress.
You will not use more than 1% of them.
Good to have all sizes book resistors kit only; 0201 to 1206.
Use scrap boards for capacitor replacements.

You can use 25V instead of 16V, but may need to make space for it.
Higher nominal voltage imply bigger package usually.