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Mystery transformer

In The Workshop

Last Post by Marconi_MPT4 9 years ago

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Marconi_MPT4

(@marconi_mpt4)

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Topic starter

On the odd occasion when I get into work in the morning a nice well-meaning person has had a clear out of their garage or shed and left the (junk) items on my desk. This time the box contained a few transformers, a 185BTA with a couple of 6SN7/6SL7 valves and some very dried up electrolytic capacitors.

A few pictures of the transformer in question...

Looks as though some components had been resting on the paxolin and each tag is numbered. Other than that no identification marks. Several tags appear to be connected to the same winding.

Any ideas?
Cheers Rich

Posted : 22/08/2014 5:02 pm

Refugee

(@refugee)

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The first thing to do is to buss it all through with a meter and draw out a diagram of the connections and resistances.

Posted : 22/08/2014 5:20 pm

Marconi_MPT4

(@marconi_mpt4)

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Hi Ref,

A quick check shows it has one centre tapped winding (pins 1, 2 and 3) with two single windings (pins 4 and 10, 6 and 9) as shown.

The centre tapped winding measures approx. 680 ohms each half, while the other two are less than 0.5 ohms. Beginning to think this may be an audio output transformer. Pin 4 is connected to the frame which is presumably 'earth'.

Rich

Posted : 22/08/2014 6:22 pm

Refugee

(@refugee)

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That must be a push pull audio output transformer with an isolated feedback winding.

Posted : 22/08/2014 6:38 pm

sideband

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It's black and has a 'Philipsy' look about it (mounting style). I'm thinking audio output with a feedback winding. The model escapes me at the moment...

Posted : 22/08/2014 8:44 pm

Marconi_MPT4

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After trawling through many, many schematics I think the transformer mystery is solved. This transformer bears a remarkable resemblance to the field output used in a 1952 Cossor 92x TV. A picture can be seen on this thread here.

Schematic for the field output stage confirms connection details previously determined.