• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Dynaco Stereo 70 Output Transformer

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Rudy,

What are the voltages at the 4.8 & 16 ohm taps on the "bad" transformer Vs what they are on the good one? To do this properly you should have a dummy resistor for each tap but that is not a likely thing to have laying around.

So, keep the 16 ohm tap on both transformers loaded with a 16 ohm speaker and measure relative voltages of all three impedance taps. It is pretty unusual, when a winding goes bad, not to have a power loss on all three, as they are usually series connected internally, each tap using the preceding winding for part of it's turns.

It is possible that Dyanco wound the 16 ohm winding as a completely separate winding, they did every other kind of strange thing to these outputs. If your measurements show a voltage drop on 4 & 8 ohm taps you will need to replace the output. Your choices there can be interesting. It is unlikely that even the Dynaclone transformers will be a perfectly matched audible replacement So you may need to budget for two new transformers. Tell us what you find.

Bud
 
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