GVP Combo card A2000-030 EC ver 4

[darkage]

+1 looks like its filtering for IC U52 DM7407M.    Check what other similar ICs are using for filtering.   ie U28, U29, etc.

It may be good to check out the board under UV, just incase theres a fault somewhere else on the board as well.

https://www.youtube.com/watch?v=g0qTOLBhlVs

(found this link which may or may not be exactly the same board with closeup pictures http://www.ebay.com/itm/GVP-68030-25mhz-accelerator-for-an-Amiga-2000-2000HD-2500-Not-Working-AS-IS-/272527223971)

[darkage]

Looking at the photos C52 looks like its only hooked up to VCC of that IC, separate from the high voltage independent gates.  You will need to trace back the tracks and confirm.

Normally 0.1uF is the standard value to smooth out ripples in the supply for IC's.

But yes it depends on noise frequency.  

Heres a good PDF that helps to explain it.  

http://www.ti.com/lit/an/scaa048/scaa048.pdf

Heres an interesting statement from Dave @ EEVBlog about picking decoupling cap values from the air.  

http://www.eevblog.com/forum/beginners/decoupling-capacitors-are-mysterious/msg91/?PHPSESSID=aa0347d6d019dabd54955486f5bf9265#msg91

[darkage]

when you replace cap.   monitor caps temp when its been powered on.    if it gets uncomfortability hot then there would be fault else where on the board.  

Good Luck!