How to Test the Wires of AMI T13 Transformer?

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mtl777diy

Well-known member
Joined
Jul 23, 2016
Messages
58
I heard that a transformer can be wired wrong at the factory.  Could someone please teach me how to test the wires of the AMI T13 transformer...

http://www.tab-funkenwerk.com/id133.html

...to see if the wiring is correct according to the spec sheet?

How about the following procedure:

1.  Measure the resistance across the yellow pair of wires (Yellow 1 and Yellow 2) by connecting one of the test leads of the multimeter to Yellow 1 and the other test lead to Yellow 2.

2.  Measure the resistance across the black pair of wires (Black 1 and Black 2) by connecting one of the test leads of the multimeter to Black 1 and the other test lead to Black 2.

3.  If the resistance measure in step 1 is greater than the resistance measured in step 2, then the yellow pair of wires should connect to capacitor and ground.  Otheriwse, if the resistance measure in step 2 is greater than the resistance measured in step 1, then the black pair of wires should connect to capacitor and ground.

I got this procedure from someone who told me, "Measure the resistance of every pair of wires.  The pair with the higher resistance should connect to capacitor and ground."  That's all he said and he did not provide any details, like which pairs of wires is he referring to.  Unfortunately, the guy is very busy and so hard to reach.  So I took it upon myself to decipher what he meant and came up with the above procedure.  Is this procedure correct?

Thanks very much!  :)
 
I wonder why did you wrote another thread about the same subject?

You can also contact ami if you have a problem with their product ;)

Just because someone said that it can be wired wrong at the factory it doesn't mean that it's.
I believe that phase of one winding can be swapped but not primary with secondary...

Ok, where's the problem?

You have full procedure described in your post.
Measure resistance between two  black wires and measure between two yellow.
Lower resistance - wires go to the XLR.

To be honest, you could just put transformer inside microphone as specs shows and test it.
If it will be wired backward, definately you will hear that.
Same with phase - use preamp with phase switch and you should hear when it is connected backward.

Look in attachement.
 

Attachments

  • T13SpecSheet.jpg
    T13SpecSheet.jpg
    86.4 KB · Views: 48
ln76d said:
I wonder why did you wrote another thread about the same subject?

I needed to get answers quick but nobody seemed to want to answer my question.  So I opened another thread, thinking that it might attract more views and get a reply.  Sorry for my impatience.  ;)

You can also contact ami if you have a problem with their product ;)

Just because someone said that it can be wired wrong at the factory it doesn't mean that it's.
I believe that phase of one winding can be swapped but not primary with secondary...

You'd be surprised how common this problem was (and still is!) with the AMI T13.  Please take a look at this thread that I found while trying to research this topic on this site:

http://groupdiy.com/index.php?topic=50533.0

Many people had low output and it was because they followed the wiring on the spec sheet which was the reverse!

Ok, where's the problem?

No problem yet.  ;)  I'm the kind of guy who wants to research things first -- like this thing someone told me -- before starting to work on a project.

You have full procedure described in your post.
Measure resistance between two  black wires and measure between two yellow.
Lower resistance - wires go to the XLR.

Thank you for verifying and confirming the procedure!  The detailed procedure I outlined was actually written by me.  I just took a guess at what was meant by the guy who told me about it but did not explain to me in detail.  I needed confirmation that my interpretation of the guy's statement is correct.  Good to know that I guessed it right!  :)

I followed the procedure and tested my newly bought AMI T13.  I got the following results:

Resistance between yellow wires = 21 Ohms
Resistance between black wires = 452 Ohms

So based on this, the yellow wires should go to XLR pin 2 and  pin 3, and the black wires should go to capacitor and ground.  WOW!  :eek:  The complete opposite of what's shown in the T13 spec sheet!  Even to this day, the AMI T13 is still wired in the reverse.  The thread I referenced was back in 2012.  Or maybe I just got a "new old stock" T13.  ;D

To be honest, you could just put transformer inside microphone as specs shows and test it.
If it will be wired backward, definately you will hear that.

It's good to get it right the first time and not have to desolder the transformer.  The test procedure is very easy to do.

Same with phase - use preamp with phase switch and you should hear when it is connected backward.

I don't have enough experience to be able to tell by listening to the output if it's out of phase.  What I learned from the past is to record something whose first sound is a transient, like one hit of a close-mic'd snare, then take a zoomed-in look at the recorded waveform.  If it is out of phase, then it will start with a negative going wave instead of positive going.

Thank you so much for chiming in on this thread!  :)
 
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