SESCOM 66J0040 Mic splitter transformer - Any info?

[elskardio]

Hi Guys,

I bought a mic splitter transformer on ebay at a good price. It's from Sescom, model 66J0040. The only info I found is the description from their catalog:

"The models 66J0036A,B (two splits), 66J0040A,B (three splits), and 66J0092A,B (four splits) are specially designed audio transformers used for splitting microphones in remote recording studios, churches and TV production. These transformers have separate isolated electro-static shields to prevent common ground-loop problems. They are enclosed in double shielded nested cans for hum protection. They can also be rotated in their mounting for minimum hum. The Mic-Splitting transformers are designed to be used in a bridging mode to maximize transfer of power without loss of signal or derating performance"

So it should be the three splits. By looking at other sescom transformer on the internet, I tough Black and White were the primary and each color pair a secondary... I ran some test with my generator + scope and I can't seem to find how it's wired.

Anyone has info on this transformer?

Thanks

2 pictures:

 

[Bo Deadly]

It could be difficult to tell which leads are the primary since they're all pretty much the same. Measure DCR and capacitance and see if one pair stands out. Maybe look at JT-MB-E datasheet for ideas which is probably very similar.

 

[PRR]

For most practical purpose, all four windings are "the same". You can feed any one and get output from three others.

So you doing it wrong or these are bad.  (Maybe fell into CJ's hands.)

 

[Winston OBoogie]

As PRR said, all windings should, for the most part, be the same. 
Most transformers I've come across tend to start windings on brown, going on from there using standard resistor colour coding.  Are you sure brown and red are not where you should be shoving your input signal?

Edit: given there is no orange or yellow, I too blame C.J.

 

[elskardio]

Hi guys,

I figured it out. If you look at the picture, the way the wires are twisted shows the correct winding pairs.

What got me confused is that every diagram I found of Sescom mic splitter transformer use Black and White as the Primary.

The Black & Blue winding measure lower resistance than the others... could it be a primary and the 3 other windings secondaries?

I ran some test and the frequency response is really good.

Thanks

 

[PRR]

Yes, it is likely the "input" winding is better performance (lower resistance) than the others. For truly optimum, 1/3rd the others. But if that made the secondaries' wire gauge too small for convenient winding they would split the difference.

 

[elskardio]

Yes, it is likely the "input" winding is better performance (lower resistance) than the others. For truly optimum, 1/3rd the others. But if that made the secondaries' wire gauge too small for convenient winding they would split the difference.

Thanks PRR

Here's the schematic for the transformer. It might be helpful for others.

The seller on ebay still have plenty in stock if you're looking for a good mic splitter. Only 15$ CAD.

https://www.ebay.ca/itm/Sescom-Mic-Splitter-Input-output-Transformer/253968971942?hash=item3b21baf8a6:g:8lIAAOSwby1bYbKR

Cheers