On Tue, 18 May 2021 08:20:15 +0100, Peter Able wrote:

snip

I'm not particularly hopeful it will do anything as even if it was
'noisy' and was allowing the voltage to fluctuate around it's entire
range, I would have thought it should still have been able to drive
the 5A load, even if also whilst fluctuating? I wonder though if that
only depends on if the PSU still works at all with (worst case), no
voltage on the wiper of the trimmer?

I'll let you know how I get on. ;-)


We all like the intellectual challenge of a difficult fault - and yet it
often ends up being a simple mechanical contact failure !

On that then, I did give the pot a good working up and down and it
didn't make any difference, but as it was simple enough to do, worth a
try (so thanks).

I have the question open elsewhere and am being guided by folk who
seem to to be fairly intimate with SMPSU's and I'm following a logical
path.

I've since measured the voltage across the two large input caps (both
showing 166V DC) and checked that there is little ripple. The next is
a couple of small electrolytic caps and an opto coupler and then what
may be a rectifier in a TOxxx package.

I think I'm understanding the working principles a bit better as well
so that's a good thing. ;-)

I also have a couple of new / better PSU's on their way so I can get
my 3D printer up and running and if I get this working I can either
keep it as a spare, put it back into use on the printer heated bed
(very basic role) or as a low voltage / high current adjustable bench
PSU with one of the eBay PSU front ends. ;-)

Cheers, T i m