[roughshawd]

I have never, replaced a capacitor with a different size or rating capacitor. However, I have some that are brand new that I will probably never use, and they are the correct voltage. The new ones are 820uf, the blown ones are 1500 and 1800... bad idea!??? no stop me... oh what should I do... I instinctively in "Shut Up mode" replaced the 1500uf with the 820's then...said to myself... I have never replaced blown cap with anything other than its rating or better... tell me is an 820uf better than a 1500uf?

 

[Harald Kapp]

is an 820uf better than a 1500uf?

There's no definitive yes or no. I some instances 820 µF instead of 1500 µF may work wll, in others it may seemingly work, but lead to quirky behavior. And in some cases it may not work at all.
Better: use the same capacity (i.e. 1500 µF) and the same or a higher voltage rating.

What you could do from a theoretical point of view is to use 2 × 820 µF in parallel instead of 1 × 1500 µF. Usually there's not enough pcb real estate to perform such a graft without using comparatively long leads - which partly negates the effect of the capacitors due to the impedance of long leads.