Universal Audio M610 Pre power transformer burnt, please help!

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customel

Member
Joined
Oct 23, 2017
Messages
11
Hello every one, I recently bought a Universal audio M610 preamp with a burnt power supply thinking it would be easy to find the replacement part, I contacted UA and they stopped servicing this model so they referred me to studioelectronics.biz so I contacted them and they also no longer work on this model nor they  have any parts left for it, these is really frustrating and can't believe that UA just don't care any more.

Please, can somebody help? Some guidance would be greatly appreciated
The toroid transformer is definitely burnt, it smells and it is shorted, nothing else looks burnt apparently nothing else seems damaged, though it really bugs me how the Transformer burnt since I've heard it is rare this happens, any Ideas how this can happen?

Does any one know where to find one of this transformers? Or who can fix it?

Thanks in advance
 
Replacing the transformer is easy,  what are the secondaries voltages?
Do you have schematics of the unit or power supply?

you say it's shorted, is it shorted on the primary/primaries or the secondaries?

Are you located in a 120V or 240V part of the World?


 
Here is an attachment with all the info of the transformer. By the way I live in Texas, USA
 

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customel said:
Here is an attachment with all the info of the transformer. By the way I live in Texas, USA
This transformer doesn't look as burnt to me. Also, there is an thermal fuse inside it, you should check it. Have you measured continuity between primary and secondary with completely disconnected transformer from boards and input connectors?
Usually, transformers do not burn just like that.
 
moamps said:
This transformer doesn't look as burnt to me. Also, there is an thermal fuse inside it, you should check it. Have you measured continuity between primary and secondary with completely disconnected transformer from boards and input connectors?
Usually, transformers do not burn just like that.

Yes, i checked off the circuit, there is continuity between the primary and secondary, the transformer smell burnt also i have not checked for a fuse in it though, here is a pic that shows better
 

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customel said:
Yes, i checked off the circuit, there is continuity between the primary and secondary, the transformer smell burnt also i have not checked for a fuse in it though, here is a pic that shows better

It's clear now. Maybe you can use this Edcor transformer:
https://www.edcorusa.com/xpwr018
It will fit in 2U chassis, and you can also ask these guys to slightly adjust secondaries to your needs.  They will wound it anyway after you place the order.
 
moamps said:
It's clear now. Maybe you can use this Edcor transformer:
https://www.edcorusa.com/xpwr018
It will fit in 2U chassis, and you can also ask these guys to slightly adjust secondaries to your needs.  They will wound it anyway after you place the order.

Thank you, that is definitely an option.
 
customel said:
Thank you, that is definitely an option.
Actually I don't see how it is. It doesn't have 24V outputs and even if they're used to make 48V, the Edcor only has a 40V output. The transformer to be replaced looks like it has secondaries:

240V 70mA
3.5V-0-3.5V 3A
24V 50mA
24V 50mA

This could be a hard to find part. I'd look on Ebay. Maybe Antek on Ebay or contact Antek directly.

Otherwise, I would just get SMPS and make an external supply. It would probably work better anyways.
 
Edcor can wind additional secondaries at any reasonable voltage. Something with several tube heaters, a Phantom winding might not even need a complete re-compute, just skimp some underutilized winding and jam the extra winding in.

It would of course be faster to find two transformers which did the job together and fit in the space.
 
The reason I asked my earlier question about the board numbers is that I bought a few of those boards a few moons ago from David K at Studio Electronics, along with the larger transformers to match (I assume these went to the dual 610 pres because they are the larger EI transformers). But the power supply board is the same for both the 2-610 and the M-610. So I was going to offer to measure up the transformer and get the voltages for you (it's unmarked other than model number).  But...

Squarewave, did you look that part up to get those winding specs? Looks like no need for me to mess with a measurement.

But PRR's right - get two transformers. Faster that way.
 
squarewave said:
Actually I don't see how it is.

You should do some research.
The original transformer is called "2-610".
There are two  small tubes, 40mA for HT and 1A for filament is more than enough.
The 24v secondaries are connected in series. 40V AC is more than enough to create phantom 48DC.
I believe the proposed Edcor transformer will work as is.

Otherwise, I would just get SMPS and make an external supply.

Examples?
 

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