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Output Transformer Questions


 
1/22/2001 5:00 PM
Erik
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Output Transformer Questions
Hi All,  
 
 
 
How can you tell when an output transformer has gone bad? What are the audible signals that its gone bad (hum, no sound, low output, etc)?  
 
 
 
Also, how can I determine whether the output transformer in my amp is working correctly? Can I test with my DMM to see if its operating correctly?  
 
 
 
Thanks,  
 
 
 
Erik
 
1/22/2001 5:15 PM
Bruce
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Some:  
 
Low power, no power, or massive distortion with low power.  
 
One tube is clipping way more then the other or no output on one side.  
 
Bruce
 
 
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1/22/2001 5:19 PM
R.G.
Bad output transformer can cause:  
 
- no sound (open or shorted secondary winding)  
 
- BAD distortion (open half-primary)  
 
- very low volume and/or distortion (resistive breakdown/internal short in primary or secondary)  
 
 
 
Any of these could also be caused by other things as well.  
 
 
 
You might want to read the applicable sections of the Tube Amp Debugging Page, which is intended to answer questions like these, and much more.  
 
 
 
In brief, use a DMM to verify that the windings are not open, and that they are not shorted to each other or to the core, and then use the output transformer short tester (article at GEO...) to verify whether or not there's an internal short.  
 
If it passes these tests and it ever once worked OK, it's good.
 
1/22/2001 6:02 PM
Erik
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Thanks for the replies guys. Actually I did check the Debugging Page, but didn't find anything on output transformers. Then, I checked it again under the heading of "no sound" or some such thing and found the info you were talking about.  
 
 
 
Regards,  
 
 
 
Erik
 
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