3 Sep
2016
3 Sep
'16
8:19 a.m.
On 09/03/2016 08:02 AM, Adrian Graham wrote:
Hi folks,
Looking at the PSU of my Lisa's ProFile after it died gracefully not so long
back and it obviously needs new caps since one of the 1000uF 16V ones has
bulged badly. While I'm replacing that one I'll do the 47uF 250V ones too.
And the mains filters but I've got a stock of spares for them already.
Apologies for what's probably a dumb question, but when it comes to cap
replacement I know I can go up a notch if the required capacitance or
voltage isn't available so 25V and 400V is ok, but what about physical size?
I can get the correct capacitance/voltage but they're physically much
smaller than the ones I'm replacing, like 10mm instead of 16mm diameter. If
I go up to 25V I can get 16mm diameter which is the size of the old ones.
Am I worrying for nothing?
Maybe not. Capacitors that are subjected to high AC ripple
current may need the large surface area for cooling.
Possibly using a low-ESR capacitor will help reduce heating,
but might have other undesirable effects.
So, you need to know a bit about the circuit and the
stresses placed on the capacitors to decide. if the ripple
current is low, then smaller caps are no problem at all.
Jon