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Hoffman Amps Forum image Author Topic: Output transformer, short question  (Read 2014 times)

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Offline John

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Output transformer, short question
« on: August 15, 2015, 01:52:47 pm »
If the secondary output tap measures zero (or under 1) ohms to the secondary common, is it dead?
Tapping into the inner tube.

Offline sluckey

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Re: Output transformer, short question
« Reply #1 on: August 15, 2015, 02:05:50 pm »
Not usually. The DCR of most 4, 8, 16 ohm secondaries will usually read very very low. It's just a length of fairly big gauge wire.
A schematic, layout, and hi-rez pics are very useful for troubleshooting your amp. Don't wait to be asked. JUST DO IT!

Offline John

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Re: Output transformer, short question
« Reply #2 on: August 15, 2015, 02:14:05 pm »
Whew. Thanks!
Tapping into the inner tube.

Offline PRR

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Re: Output transformer, short question
« Reply #3 on: August 15, 2015, 09:50:00 pm »
You want the _DC_ resistance of the winding to be much less than the load, so it don't waste power.

Ideally zero, but we can't have that.

"Much less" than 4-8-16 Ohm speakers is typically an Ohm or less. And most meters won't read 1 Ohms well.

Don't worry about it.

Offline John

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Re: Output transformer, short question
« Reply #4 on: August 16, 2015, 05:35:18 am »
Thank you.


I just finished re-building my amp (added spring reverb and such) and had no sound, not even hum. I think I had a bad joint at the speaker jack. Now she sings.


And spring reverb is cooooolllllllll.
Tapping into the inner tube.

 


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