[gareth magennis]

On Friday, 5 March 2021 at 10:14:00 UTC, gareth magennis wrote:
On Friday, 5 March 2021 at 09:46:05 UTC, wrote:
gareth magennis wrote:

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The ringing isn't necessarily the problem. The problem is that under certain conditions the unit oscillates at 90Hz,
a phenomenom I still have not witnessed, but this has been confirmed by the company as a known issue with
this early production unit.
The ASSUMPTION is that the ringing is somehow the cause of the 90Hz oscillation, and reducing the ringing will solve the problem.

The company issued a mod to tackle the 90 Hz problem, but we don't know what that mod is,
or whether it is designed to reduce the ringing, or whether the mod adresses a different issue altogether.

** I once heard about a tribe of African natives who had not figured the cause of female tribe members becoming pregnant.

Witch doctors invented many semi plausible theories, which tribe members were obliged to believe.
Most involved the intervention of spirits and animal gods.

Do you see any parallel here yet ??



.... Phil
Ok, my last post got me thinking.

I posted earlier that 100 ohms in series with around 2nF produced full blown oscillations.
I was scoping the ringing at the time, didn't have audio monitoring connected, and didn't notice that it was motorboating at a few Hz as I didn't want the unit to be oscillating like that for long.

So this recreates the symptoms. Full blown oscillations of around 100kHz and 60v pk to pk dumps the power supply and it motorboats.

The ringing is at the same frequency.

Pic here.
https://imgur.com/YmkTq5N