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-   -   HELP! Power transformer hot and hums. (http://www.diyaudio.com/forums/tubelab/229786-help-power-transformer-hot-hums.html)

kkcinc 11th February 2013 02:05 AM

HELP! Power transformer hot and hums.
 
I bought this to replace the Allied and it seems to run as hot with more hum. Rated At 200ma vs. 175ma. Using 6550/5ar4/6201. I am still very new to this so don't make fun of me, but are power transformers supposed to hum? (Fairly loud) The amplifier works fine and sounds good so I think wiring is correct. I've had it running fine for quite a while with the Allied transformer. There is no hum whatsoever out of the speakers, just the transformer itself. Anyone out there using this transformer?

EDCOR - XPWR033-120

counter culture 11th February 2013 03:47 AM

A new transformer should neither run hot nor hum. They do though, but it shouldn't hum at an annoying level in a sensible installation and it should be warm, but not hot.

The first thing, you have a lot of voltage there, even with a choke input PSU.

Perhaps it'd be best if you gave a description or other details of the circuit.

kkcinc 11th February 2013 06:10 AM

Tubelab sse. Optional choke and cap. 560ohm cathode resistor. Running in ul with two 6550. One 5ar4. One 12at7.

AJT 11th February 2013 06:48 AM

Quote:

Originally Posted by kkcinc (Post 3364833)
I bought this to replace the Allied and it seems to run as hot with more hum. Rated At 200ma vs. 175ma. Using 6550/5ar4/6201. I am still very new to this so don't make fun of me, but are power transformers supposed to hum? (Fairly loud) The amplifier works fine and sounds good so I think wiring is correct. I've had it running fine for quite a while with the Allied transformer. There is no hum whatsoever out of the speakers, just the transformer itself. Anyone out there using this transformer?

EDCOR - XPWR033-120

without knowing your actual temperature, it is hard to make a judgement, as per specs, classB insulation, as long as you do not exceed that temperature you should be fine...

as to traffo humming, are you using steel chassis? if so, rubber pads underneath the traffo mounting can help....

kkcinc 11th February 2013 12:22 PM

Ok. Give me a little time. I'll get it good and hot, then check the temperature with my meter. Yes it is a steel chassis the previous one hummed, but not like this. Same chassis. Have the kids today so could be a while please keep checking on me. It won't blow up, will it?

AJT 11th February 2013 12:35 PM

you can do the 5 seconds test, hold it with both hands and count 5 seconds, if you can not stand the heat by then, then it is really hot....

how many minutes before the traffo turns hot?

dimkasta 11th February 2013 01:07 PM

Running hot and vibrating is an indication that something is wrong. Either the transformer is small for the application or there is a wiring issue. The second being seriously dangerous. Double check your wiring

kkcinc 11th February 2013 01:21 PM

Agreed! I'll take it apart later. Thanks. Funny thing is, it sounds really good.

BillEpstein 11th February 2013 02:54 PM

Don't know about the heat, but I mount all my transformers on EAR Isodamp SD-40, available from Michael Percy.

Unlike other damping materials, there's no anecdotal or magical qualities to EAR products; they are thoroughly tested (the results are on their webpages).

EAR Specialty Composites -- Isodamp, Isoloss, VersaDamp, Tufcote, Confor

dimkasta 11th February 2013 02:58 PM

Well this is intended to be used with minor hum/vibration cases that can occur either from working near the trafo's specs or when there is some DC in the power network.
Having a trafo that works hot and fairly loud is an indication of problems.


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