11 Sep
2025
11 Sep
'25
9 a.m.
-----Original Message-----
From: Christian Corti via cctalk <cctalk(a)classiccmp.org>
Sent: 11 September 2025 08:31
To: Rob Jarratt via cctalk <cctalk(a)classiccmp.org>
Cc: Christian Corti <cc(a)informatik.uni-stuttgart.de>
Subject: [cctalk] Re: Repairing an Olivetti M24 PSU
On Sat, 6 Sep 2025, Rob Jarratt wrote:
I tested most electrolytics for ESR in-circuit. When I am back home I will see about
opening up the PSU again and checking this and all the other things that I have had
suggested.
Thanks
Rob
I thought that replacing two big output
capacitors on the +5V output
had fixed the issue but it hasn't. The problem seems to be
intermittent. I tested it a couple of days ago with a simple resistive
load on the +5V and +12V outputs. The first two times I switched it on
it operated normally. The third time I got no output at all. It seems
to start working again after I leave it switched off for a few
minutes. Over the last couple of days I have tested it multiple times
very briefly with the resistive load and it has worked every time.
Did you test/replace the startup voltage capacitor on the primary side? It is
usually a small one (e.g. 10µF/50V) around the switching controller, and often
located near a heat sink and thus prone to fail.
BTW check all capacitors near heat sinks or power components.
Christian