Sujet : Re: PSU Ripple Update
De : jl (at) *nospam* 997PotHill.com (John Larkin)
Groupes : sci.electronics.repair sci.electronics.designDate : 17. Mar 2024, 20:33:12
Autres entêtes
Organisation : Highland Tech
Message-ID : <mmdevil3si3to2l68lhrk9geoibkrm721r@4ax.com>
References : 1
User-Agent : Forte Agent 3.1/32.783
On Sun, 17 Mar 2024 17:48:07 +0000, Cursitor Doom <
cd@notformail.com>
wrote:
Gentlemen (and others)
>
I only get a few spare minutes a week to look into this, hence this
update. Hopefully my latest finding might ring a bell for some of you
and assist in pinpointing the fault with this (linear) PSU.
So, I've carried out a few more tests and discovered that there is a
total absence of ripple on the storage caps when all the downstream
circuitry has been disconnected. So it's totally fine with no load.
However, as I re-connect all those downstream circuits, the ripple
commences and the more connectors I re-attach, the worse it gets. This
is a screen shot showing over a volt of ripple at only about 66% of
the full supply voltage applied:
>
https://disk.yandex.com/i/vgxfpXgNp-F4Yg
>
Now I did check to see if there was anything downstream which had
shorted or gone low-resistance which could possibly account for this,
but found nothing amiss. So the question is:
What could cause ripple to arise when even very light loads are
applied to the output of a pretty substantial linear PSU?
>
BTW, the bridge rectifiers were fine and have been exonerated from any
culpability in this fault.
Is there actually a fault? Transformer-rectifier supplies have ripple.