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00940 7th April 2004 06:38 PM

How to check output transformers ?
I've been given a pair of output transformers by a friend. Is there a quite easy way to test them ? I've no oscillope at home, just a dmm. All procedures I found on the web take for granted that the xformers are still on the amp.

They're quite small, coming from a stereo amp with just a pair of EL84. There are four wires coming out of each xformer.

Btw, would someone know from which brand are tubes with this marking ? :

fdegrove 7th April 2004 10:32 PM


The CV letter code FB is probably STC in Footscray.

KB I see alot on CV valves but I don't know what it stands for.


EC8010 7th April 2004 10:51 PM

I'm afraid your output transformers are traditional 3W single-ended transformers and are probably terrible. On the other hand, if you want to experiment and learn, then they are ideal. Try looking at the Mullard 3-3 circuit. The winding with the higher resistance is the primary, and goes between HT and anode. The (much) lower resistance winding is the loudspeaker output (probably 4 Ohm).

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