Transformer Fault in a PSU?

Jon Elson elson at
Sun Jan 12 22:48:53 CST 2020

On 01/12/2020 10:34 PM, Stefan Skoglund via cctalk wrote:
> sön 2020-01-12 klockan 21:10 +0000 skrev Rob Jarratt via cctalk:
>> The PSU in my VAXmate failed recently and I think I have found a
>> problem
>> with one of the windings on the transformer not ringing when I test
>> it with
>> a ringing tester. The technical description of the VAXmate says that
>> one
>> winding is operated in flyback mode and I wonder if that has any
>> bearing on
>> the ringing test. Also, one of the pins appears not to be connected
>> to
>> anything else, so possibly a broken (melted?) wire.
>> Can anyone help with the following questions:
> The transformer is basically only intended to provide AC at a specific
> voltage while preventing surges and noise from the utility to create
> havoc.
> What voltage is it specified to provide ? If so, can it be replaced
> with maybe a new AC to AC device ?
The transformer Rod describes and provided schematic for is 
part of a switching power supply,
and not a 50/60 Hz mains transformer.  From the picture, it 
is almost certainly a ferrite core
transformer running at 25+ KHz.


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