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Vintage Audio (record players, hi-fi etc) Amplifiers, speakers, gramophones and other audio equipment. |
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2nd Mar 2006, 7:26 pm | #1 |
Retired Dormant Member
Join Date: Sep 2003
Location: USA Long Island New York
Posts: 28
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Testing Push Pull Output Transformers
I've been working on some amplifiers of this type and been finding the output transformers to be shorted.
I have few that may be a good match, but not sure of their speaker ohms and if they are good. Is there an easy test to check the primary and the secondery on these transformers with a Fluke Multi Meter to see if they are sure to be good Also how would one find out the ohms on the speaker side, Thanks for any advise Regards, Jim |
2nd Mar 2006, 9:02 pm | #2 |
Dekatron
Join Date: Aug 2003
Location: near Reading (and sometimes Torquay)
Posts: 3,086
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Re: Testing Push Pull Out Put Transformers
If you don't have any equipment to directly measure the turns ratio then feed a few volts a/c into the speaker winding and measure all the voltages with an a/c voltmeter. From this you can calculate the turns ratio, being the ratio of the voltages. Then the primary impedance is the speaker impedance times the turns ratio squared.
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2nd Mar 2006, 9:17 pm | #3 |
Dekatron
Join Date: Jan 2004
Location: Newcastle upon Tyne, Tyne & Wear, UK.
Posts: 8,171
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Re: Testing Push Pull Out Put Transformers
Hi Jim, thats about the best way to test an OP tranny as JMB says. It will not normally show up a few shorted turns. This can be a common fault, especially on guitar amps and it difficult to detect without pulse testing gear.
Ed |
2nd Mar 2006, 10:51 pm | #4 |
Nonode
Join Date: Jun 2004
Location: Norwich, Norfolk, UK.
Posts: 2,543
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Re: Testing Push Pull Out Put Transformers
Hi Jim,
Everything is explained very well on this page http://www.radioremembered.org/outimp.htm HTH David |