Kofi Annan in: "Hummin' Trafo Blues" - diyAudio
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Old 15th October 2005, 07:23 PM   #1
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Default Kofi Annan in: "Hummin' Trafo Blues"

So, just installed Dave's (Planet 10's) phase plugs and started up the phono pre and suddenly, without warning, the power transformer started humming like it was in a barbership quartet. Its pretty loud.

I engaged in the wiggle test, which consists of me wiggling the transformer until it stopped humming. A hard wiggle-and-hold move to the right stopped the humming altogether, but I don't really enjoy music when I have to hold on to the transformer to listen to it.

Its still putting out the correct voltage and the circuit works. Its just humming.

Bad.

So, is it possible that a winding has shorted? I took the damn thing out of an old Piolt tube amp and its been working faithfully for several months now. I guess its possible that I'll be in the marker for a new transformer, but if that's the case, can I still operate it at my own risk for now?

I know. Bad idea. But I really want to listen to these thngs now!

Is it only me that this stuff happens to?

Any recommendations would be greatly appreciated.

Your pal,
Kofi
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Old 15th October 2005, 09:52 PM   #2
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If your transformer had shorted to its chassis, the name of this thread might have been Kofi Annan in: "The Jitterbug Blues"...which is why you always need to ground your transformer chassis.

I don't know what type of trafo it is, but if your voltages are still in the normal range, it's probably not electrical in nature, but mechanical.
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Old 15th October 2005, 10:45 PM   #3
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I don't know what type of trafo it is, but if your voltages are still in the normal range, it's probably not electrical in nature, but mechanical.
Thanks! I actually moved the transformer back in the chassis a litle bit and that helped diminish the hum. The transformer doesn't get hot and the voltage is fine, just started to get hum.

Does this mean its OK to operate it this way? Also, since you alluded to a mechanical issue, what mechanical forces are in play that could cause this?

Thanks so much for your input!

Kofi
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Old 16th October 2005, 07:51 PM   #4
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Old 17th October 2005, 01:58 AM   #5
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Well,since you say it's from an old Pilot tube amp,I'll assume it's a big E-I type of tranny..
Does it have bolts through it,to hold the core and endbells together?
Try tightening the bolts/screws that hold the core together,that will usually help,atleast a little.
Also,perhaps try tightening any metal chassis panels or anything near the tranny..Sometimes the magnetic field can make nearby metal parts vibrate a bit.
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Old 17th October 2005, 02:03 AM   #6
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I've also read of DC bias on the mains causing toroids to buzz.
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Old 17th October 2005, 06:25 AM   #7
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Quote:
Originally posted by Kofi Annan
Does this mean its OK to operate it this way? Also, since you alluded to a mechanical issue, what mechanical forces are in play that could cause this?
If from a pilot it is an EI... some loose Es or Is can vibrate as the AC pours thru it causing a hum... make sure all the bolts that hold it together are tight.

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Old 17th October 2005, 12:58 PM   #8
Sherman is offline Sherman  United States
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Quote:
Originally posted by planet10


If from a pilot it is an EI... some loose Es or Is can vibrate as the AC pours thru it causing a hum... make sure all the bolts that hold it together are tight.

dave

Dave's advice is very good. I salvaged and old PT from a 60's console and it buzzed like crazy. I tried to tighten the bolts and they wouldn't move. Turns out the threads were stripped, apparently when someone tried removing the bells to paint it. I cut off the old bolts and put in new ones tightened down pretty well and the buzz was gone. (I just guessed at how tight to make things though. No idea if there was a certain ft/lb of torque to apply.)
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Old 17th October 2005, 01:28 PM   #9
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how about trying to remove Planet10's phase plugs?
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Old 17th October 2005, 10:52 PM   #10
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Quote:
Try tightening the bolts/screws that hold the core together,that will usually help,atleast a little.
Quote:
If from a pilot it is an EI... some loose Es or Is can vibrate as the AC pours thru it causing a hum... make sure all the bolts that hold it together are tight.
Quote:
Dave's advice is very good.
Screws tightened. Hum gone. Problem solved.

Thanks DIYAudio!

Kofi
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