[thathertz]

Quote:

Originally Posted by HeadphoneAddict /img/forum/go_quote.gif What happens if you put an egg on the trafo? Does it get cooked?

Hi Larry

It's 3:22am right now.
I'll try this tomorrow morning.
If I succeed I'll perhaps throw some Danish bacon on there
and at least enjoy a full breakfast while I consider the consequences

 

[HeadphoneAddict]

Quote:

Originally Posted by thathertz /img/forum/go_quote.gif Hi Larry It's 3:22am right now. I'll try this tomorrow morning. If I succeed I'll perhaps throw some Danish bacon on there and at least enjoy a full breakfast while I consider the consequences

BACON!

 

[thathertz]

Quote:

Originally Posted by HeadphoneAddict /img/forum/go_quote.gif BACON!

Oh yeah. DANISH Bacon

I can almost smell it now...

(Or is that my transformer?)

 

[Skylab]

I have to say this - I don't have a single tube amp whose transformer does not get hot during use...

 

[spritzer]

It sure sounds like your amp has a Hammond filament transformer acting as a high voltage unit. If we look past how utterly stupid this is, the transformer is running way out of spec and is slowly burning up. A transformer run on the limit is warm but never hot.

 

[thathertz]

Don't know if you can identify the transformer by this but here's
my MPX3:

http://www.head-fi.org/forums/f42/sold-431635/

 

[thathertz]

From : Angela Instruments Online Catalog - Transformers

Looks like you're right Spritzer.

So what's the next step?

 

[thathertz]

Quote:

Originally Posted by spritzer /img/forum/go_quote.gif It sure sounds like your amp has a Hammond filament transformer acting as a high voltage unit. If we look past how utterly stupid this is, the transformer is running way out of spec and is slowly burning up. A transformer run on the limit is warm but never hot.

Spritzer, could you please explain why this is so stupid and what
could be done to improve / fix the situation?

 

[spritzer]

Looks like your amp doesn't have a filament only transformer but one of the 270 range from Hammond. They are a plate+filament combo transformers but 115v only. With the sticker removed it will be hard to identify it unless you take note of the wires it has, it's exact dimensions and how much it weighs and compare that to the Hammond spec sheet. These transformers are available in a range of sizes so you could very well be driving it past its limits now. There is a 370 range though which can be configured for 230v operation so your best bet would be to upgrade to one of those that can handle the current needed.

As for running the second primary as a secondary, it was never designed to run this way and it cuts the power current capability of the transformer in half. You are cooking the single primary to say the least...

 

[n_maher]

Quote:

Originally Posted by thathertz /img/forum/go_quote.gif http://angela.com/images/categories/272BXOne.jpg From : Angela Instruments Online Catalog - Transformers Looks like you're right Spritzer. So what's the next step?

The transformer on your amp, while a Hammond, is not at all the same as the small filament trafo that we're talking about in the Extreme thread. I should make something very clear here, the problem in the Extreme is not that Hammond was the man'f of the trafo, only that a transformer that they man'f was improperly used. I've built a number of things using their products and when used properly they perform just fine.

 

[thathertz]

Quote:

Originally Posted by n_maher /img/forum/go_quote.gif The transformer on your amp, while a Hammond, is not at all the same as the small filament trafo that we're talking about in the Extreme thread. I should make something very clear here, the problem in the Extreme is not that Hammond was the man'f of the trafo, only that a transformer that they man'f was improperly used. I've built a number of things using their products and when used properly they perform just fine.

Sure Nate, I'm sure the trafos are good quallity.

Even though it's a different trafo than the one in the Extreme, the still
issue still applies though: the transformer is being driven beyond it's
capabilities?

Nate, could you or perhaps Spritzer recommend a suitable current rating
for the Hammond 370 trafo?

Thanks for your help.

 

[kevin gilmore]

See the thing about the hammond 300 series transformers is that they
are designed to run a tube rectifier. A significant amount of current goes
into the 5 volt winding, or multiple 5 volt windings. The transformer is a stock
unit, not really rated for what it is being used for. Unfortunately, i have not
been able to find a stock transformer that is perfect for use with extremes.
You have to buy a custom unit, And if you have a balanced extreme, you
can have 20 amps rms on the filament windings with 64 amp peaks due to
the way the filament DC is generated from the AC.

 

[spritzer]

Forgot about the damn 5V tap...

Looks like the Hammond units are a no go. With the spec in hand there might be something which fits the bill or perhaps adding a small filament transformer inside the chassis would work. A 4A Hammond unit is pretty small...

 

[Skylab]

I have the exact same transformer on my MPX3 as thahertz does. So assuming in was wired for correct use, and not the incorrect way the Extremes seem to have been wired, since mine is not a "12V" model - no voltage switch, etc. -- it would seem to have enough current delivery to handle it's application:

272BX 95VA, sec. 300-0-300, DC ma 100, Fil.#1(rct) 5.0v @ 2a, Fil.#2(htr) 6.3v @ 3.0a.

3 amp delivery at 6.3V for heater current - even using 3 ECC32's which draw .9a, this would seem to be in spec.

Am I reading this correctly? I realize this doesn't mean my MPX3 might not have other issues...

 

[SmellyGas]

WOW, this Mikhail guy is turning into the Madoff of tube amps.