Mills 5900-B 2A3 Amp Input Transformer question...

[rudy18d]

Greetings,

I am working on a late 30s Mills amplifier from an Empress model jukebox.  This is the first Mills component I have worked on and besides the frustration of having only Mills part numbers (no voltages/Ohms/capacitance) on an otherwise legible schematic ... it seems pretty straight forward.

However, the Input Transformer is not a typical one in that it is a 4"x2.5"rectangular metal cannister on top of the amp and is filled solid with paraffin wax. Since I have no voltage information for any of the components, I am limited on how to test it. I can certainly use the VOM to see it has an open coil or not but other than that I can't think of another way.

My question to the group is based on your experiences, do these types of Input Transformers "usually" go bad? ~85 years is a long time I would think for a transformer like this. I do have a manual that covers the Empress model, but it has no details about the transformer besides the part number and the name "MCP 6075- P.P. Input Transformer". And if it is bad, how would I go about finding a comparable replacement without any other imformation?

Thanks for the help!
Rudy

[jukenorman]

Hi Rudy,
In first principles, what is a transformer but coils of insulated wire wound around a metal core? So yes you can test the windings for continuity. The secondary is centre tapped so you would probably find that the two sides show different resistances although the number of turns are equal. Depending on the test equiopment you have, you could inject a sine wave from a signal generator into the primary and view the secondary windings on an oscilloscope for example.

Transformers do go bad although that is usually down to some form of abuse (overload, moisture ingress etc). I don't think you should worry too much about a replacement until you actually realise that it's bad.  Edit - I just checked Hammond Transformers and they have a selection of interstage transformers so I don't think you would be be stuck!

Norman.

[rudy18d]

Great feedback Norman. Can always count on you to know or find an answer for my questions. Much appreciated.

Cheers.

[rebo]

Hi Norman. I belatedly realized that you, too, are working on a Mills Empress jukebox. My husband and I acquired one late July of this year (my birthday present), and want to start restoring it. Our experience with 1930s and 1940s jukeboxes is limited to Rockolas and Wurlitzers. Opening up the back of this box doesn’t look like anything we have worked on before and has us stymied. Do you have any pictures of your restoration in progress or suggestions or thoughts? 
Thank you for any help you can send our way.
rebo

[jukenorman]

No it's Rudy who is working on the Empress, not me - and he hasn't visited the forum for over a month.

Norman.

[rebo]

Yep, I’m wrong! So excited about someone working on a similar jukebox that I didn’t follow the conversation closely enough! Thanks for setting me straight!
rebo